Estimation of Fracture 

Toughness of Cast Stainless 

Steels during Thermal Aging 

in LWR Systems

Office of Nuclear Regulatory Research

NUREG/CR-4513

ANL-15/08

Revision 2

Estimation of Fracture 

Toughness of Cast Stainless 

Steels during Thermal Aging 

in LWR Systems

Manuscript Completed: June 2015

Date Published: May 2016

Prepared by: Omesh K. Chopra

Argonne National Laboratory

Argonne, IL 60439

Appajosula S. Rao, NRC

Technical Monitor and Project Manager

NRC Job Code Number V6455

Office of Nuclear Regulatory Research

NUREG/CR-4513

ANL-15/08

Revision 2

iii

ABSTRACT

Cast austenitic stainless steel (CASS) materials are used extensively in reactor coolant 

pressure boundary systems as well as core support structure and reactor internals. However, 

these materials have a duplex structure consisting of austenite and ferrite phases and are 

susceptible to thermal aging embrittlement during reactor service. In addition, the prolonged 

exposure of these materials to neutron irradiation changes their microstructure and 

microchemistry, which can degrade their fracture properties even further. This report is a 

revision of NUREG/CR-4513, Rev. 1, ANL-93/22 (August 1994); it revises the procedure and 

correlations used for predicting the change in fracture toughness and tensile properties of CASS 

components due to thermal aging during service in light water reactors at 280–330°C 

(535–625°F). The updated correlations are based on the current fracture toughness database 

for CASS materials aged up to 100,000 h at 290–350°C (554–633°F). The methodology for 

estimating fracture properties has been extended to cover CASS materials with a ferrite content 

of up to 40%. The correlations for estimating the change in tensile stress, including the 

Ramberg/Osgood parameters for strain hardening, are also described. The fracture toughness 

J-R curve, tensile stress, and Charpy-impact energy of aged CASS materials are estimated 

from material composition. The mechanical properties of a specific CASS material are 

estimated from the extent and kinetics of thermal embrittlement. Embrittlement is characterized 

in terms of room temperature Charpy-impact energy. The extent or degree of thermal 

embrittlement at “saturation” (i.e., the minimum impact energy that can be achieved for a 

material after long-term aging) is determined from the chemical composition of the material. 

Charpy-impact energy as a function of the time and temperature of reactor service is estimated 

from the kinetics of thermal embrittlement, which are also determined from the chemical 

composition. Data on the initial impact energy and tensile flow stress of the unaged material are 

required for these estimations. The fracture toughness J-R curve for the material is then 

obtained by correlating room temperature Charpy-impact energy with fracture toughness 

parameters. The values of JIc are determined from the estimated J-R curve and flow stress. A 

common “predicted lower-bound” J-R curve for CASS materials of unknown chemical 

composition is also defined for a given grade of steel, range of ferrite content, and temperature. 

In addition, guidance is provided for evaluating the combined effects of thermal and neutron 

embrittlement of CASS materials used in the reactor core internal components.

v

CONTENTS

ABSTRACT ................................................................................................................... iii

CONTENTS .................................................................................................................... v

LIST OF FIGURES........................................................................................................ vii

LIST OF TABLES .......................................................................................................... xi

EXECUTIVE SUMMARY ............................................................................................. xiii

ACKNOWLEDGMENTS ............................................................................................. xvii

ABBREVIATIONS AND ACRONYMS......................................................................... xix

NOMENCLATURE....................................................................................................... xxi

1 INTRODUCTION..................................................................................................... 1

2 THERMAL EMBRITTLEMENT OF CAST STAINLESS STEELS .......................... 7

2.1 Mechanism of Thermal Embrittlement .......................................................................7

2.2 Distribution and M0orphology of Ferrite in CASS Materials .....................................11

2.2.1 Ferrite Morphology.......................................................................................11

2.2.2 Ferrite Content.............................................................................................13

2.2.2.1 Measured Ferrite ..........................................................................15

2.2.2.2 Estimated Ferrite ..........................................................................16

2.3 Kinetics of Thermal Embrittlement...........................................................................18

2.4 Extent of Thermal Embrittlement .............................................................................26

2.4.1 Charpy-Impact Energy .................................................................................26

2.4.2 Effect of Trace Nb Content...........................................................................32

2.4.3 Fracture Toughness J-R Curve....................................................................33

2.4.3.1 Potential Effects of Reactor Coolant Environment ........................41

2.4.3.2 Potential Effects of High Loading Rate..........................................43

2.5 Methodology for Estimating Thermal Embrittlement of CASS Materials...................44

3 ASSESSMENT OF THERMAL EMBRITTLEMENT ............................................. 49

3.1 Estimation of Thermal Embrittlement of CASS Materials of Known Composition 

and Service Condition – Service Time Values .........................................................49

3.2 Estimation of the Thermal Embrittlement of CASS Materials of Unknown 

Composition: Lower-Bound Values..........................................................................54

3.3 Screening Criteria for Susceptibility of CASS Materials to Thermal 

Embrittlement ..........................................................................................................56

3.4 Estimation of Tensile Flow Stress............................................................................63

4 USE OF METHODOLOGY IN ASME CODE, SECTION XI.................................. 69

4.1 Current Editions of the ASME Code Section XI .......................................................71

5 COMBINED EFFECTS OF THERMAL AND NEUTRON EMBRITTLEMENT..... 73

5.1 Fracture Toughness of Irradiated Austenitic Stainless Steels ..................................74
vi

5.1.1 Fracture Toughness JIc ...............................................................................76

5.1.2 Fracture Toughness J-R Curve....................................................................78

5.1.2.1 Irradiation Conditions....................................................................78

5.1.2.2 Material Type................................................................................78

5.1.2.3 Test Temperature .........................................................................80

5.1.2.4 Test Environment..........................................................................81

5.1.2.5 Irradiation Temperature ................................................................82

5.2 Lower-Bound Fracture Toughness Curve ................................................................83

5.3.1 Methodology for Incorporating Irradiation Effects on CASS Materials 

including the Combined Effects of Thermal and Neutron Embrittlement.......88

5.3.1.1 Threshold Neutron Dose for Irradiation Effects .............................88

5.3.1.2 Potential Effects of Thermal and Neutron Embrittlement...............89

6 SUMMARY ........................................................................................................... 91

7 REFERENCES...................................................................................................... 95

APPENDIX A: MATERIAL INFORMATION............................................................. A-1

APPENDIX B: J-R CURVE CHARACTERIZATION ................................................ B-1

Data Analysis Procedure ...........................................................................B-2

Data Qualification ......................................................................................B-5

APPENDIX C: EXPERIMENTAL AND ESTIMATED CHARPY-IMPACT DATA 

FOR AGED CASS MATERIALS...................................................... C-1

APPENDIX D: REFERENCES................................................................................. D-1

APPENDIX E: PREVIOUS DOCUMENTS IN SERIES .............................................E-1
vii

LIST OF FIGURES

1. Time-temperature curve for the formation of various phases in CASS materials. ...............8

2. Deformation twins in a Charpy-impact specimen of CF-8 material aged for 30000 h 

at 350°C and tested at 290°C.............................................................................................9

3. Pseudo binary diagram for Fe-Ni-19%Cr alloy..................................................................11

4. Microstructure along the axial and circumferential sections of centrifugally cast CF-8 

and CF-3 stainless steel pipes showing equiaxed grain structure.....................................12

5. Microstructure along axial section of a check valve from the decommissioned 

Shippingport reactor showing columnar grains.................................................................12

6. Ferrite content and morphology of vanes of a static cast CF-3 pump impeller and 

along a circumferential section of regions near the inside and outside diameter of 

centrifugally cast CF-3 and CF-8 pipes.............................................................................14

7. Plots of measured ferrite content and values for various CASS materials calculated 

by using Hull's equivalent factor. ......................................................................................16

8. Plots of measured ferrite content and values for various CASS materials calculated 

using the ASTM A800/A800M methodology. ....................................................................17

9a. Plots of ferrite content calculated by using Hull's equivalent factor and those 

estimated from the ASTM A800/A800M methodology for various CASS materials...........18

9b. Plots of ferrite content for various CASS materials calculated by using Hull's 

equivalent factors and those determined from the EMA formula developed by EdF. ........19

10. Plots of ferrite content for various CASS materials estimated by using the ASTM 

A800/A800M methodology and those determined from the EMA formula developed 

by EdF..............................................................................................................................19

11. Arrhenius plots for the formation of the G phase and a reduction in impact energy. .........21

12. Decrease in Charpy-impact energy for various heats of CASS materials aged at 

400°C...............................................................................................................................22

13. Correlation between RT Charpy-impact energy at saturation and the material 

parameter φ for CASS materials.......................................................................................27

14. Comparison of the updated (chain-dash line) and original (solid line) correlation 

between the RT Charpy-impact energy at saturation and material parameter φ................29

15. Measured values of saturation RT Charpy-impact energy for CF-3, CF-8, and CF-8M 

CASS materials and those estimated from (a) the material parameter φ, (b) the 

material composition and ferrite content, and (c) the lower of these two values................30
viii

16. Correlation between RT Charpy-impact energy at saturation and the ferrite content 

for CF-3, CF-8, and CF-8M materials. ..............................................................................31

17. Fracture surface of Charpy-impact specimen of Heat 4331 aged for 700 h at 400°C 

and tested at room temperature. ......................................................................................32

18. Ductile-to-brittle transition curves for Charpy-impact specimens of thermally aged 

Heats 4331 and 75 of CF-8M material..............................................................................33

19a. Correlation between RT Charpy-impact energy and coefficient C at RT for CF-3, 

CF-8, CF-3M, and CF-8M CASS materials.......................................................................33

19b. Correlation between RT Charpy-impact energy and coefficient C at 290–320°C for 

CF-3, CF-8, CF-3M, and CF-8M CASS materials.............................................................34

20. Distribution of the J-R curve exponent for various grades of thermally aged and 

unaged CASS materials at (a) room temperature and (b) 290–325°C..............................36

21. Correlation between the RT Charpy-impact energy and exponent n of the power-law 

J-R curve at RT and 290°C for CF-8M materials. .............................................................37

22. Distribution of ferrite content in CASS grades of (a) CF-8, (b) CF-8A, (c) CF-8M, and 

(d) CF-3 piping material in Westinghouse PWRs..............................................................40

23. Fracture toughness J-R curves for sensitized Type 304 SS in simulated BWR 

coolant at 288°C and three different displacement rates. .................................................41

24. Fracture toughness J-R curve data for thermally aged Heat 68 of CF-8M plate at 

54°C.................................................................................................................................42

25. Fracture toughness J-R curves for thermally aged CF-3M at 0°C and quasi-static 

and dynamic loading rates................................................................................................43

26. Flow diagram for estimating mechanical properties of thermally aged CASS 

materials in LWR systems................................................................................................44

27. Predicted and measured fracture toughness J-R curves for unaged materials 

(a) CASS at 290–320°C and (b) wrought austenitic SSs at various temperatures. ...........45

28. Estimated and experimental values of coefficient C of the J-R curve for static-cast 

CF-3 plate during thermal aging. ......................................................................................50

29. Estimated and experimental values of coefficient C of the J-R curve for static-cast 

CF-8 plate during thermal aging. ......................................................................................50

30. Estimated and experimental values of coefficient C of the J-R curve for static-cast 

CF-8M plate during thermal aging. ...................................................................................50

31. Estimated and experimental values of coefficient C of the J-R curve for centrifugally 

cast CF-8 pipe during thermal aging.................................................................................51
ix

32. Experimental and estimated fracture toughness J-R curves at RT and 290°C for an 

ANL heat of a static cast CF-8 plate. ................................................................................51

33. Experimental and estimated fracture toughness J-R curves at RT and 290°C for an 

ANL heat of a static cast CF-3 plate. ................................................................................51

34. Experimental and estimated fracture toughness J-R curves at RT and 290°C for an 

ANL heat of a centrifugally cast CF-8 pipe. ......................................................................52

35. Experimental and estimated fracture toughness J-R curves at RT and 290°C for an 

ANL heat of a static cast CF-8M plate. .............................................................................52

36. Experimental and estimated fracture toughness J-R curves at RT and 290°C for an 

ANL heat of a static cast CF-8M plate. .............................................................................53

37. Experimental and estimated fracture toughness J-R curves at RT and 290°C for an 

EdF heats of a static cast CF-8M plate (Ht. DI) and a 50° elbow. .....................................53

38. Experimental and estimated fracture toughness J-R curves at RT and 290°C for a 

MHI heat of a static cast CF-8M pipe. ..............................................................................53

39. Correlation between saturation RT Charpy-impact energy and ferrite content..................54

40. Estimated lower-bound J-R curves at RT for static-cast CASS materials with ferrite 

contents of >25–30%, >20–25%, and >15–20%...............................................................57

41. Estimated lower-bound J-R curves at 290–320°C for static-cast CASS materials with 

ferrite contents of >25–30%, >20–25%, and >15–20%.....................................................58

42. Estimated lower-bound J-R curves at RT for centrifugally cast CASS materials with 

ferrite contents of >25–30%, >20–25%, and >15–20%.....................................................59

43. Estimated lower-bound J-R curves at 290–320°C for centrifugally cast CASS 

materials with ferrite contents of >25–30%, >20–25%, and >15–20%. .............................60

44. Saturation J at a 2.5 mm crack extension as a function of the ferrite content for 

static-cast CF-3, CF-8, and CF-8M CASS materials.........................................................61

45. Saturation J at a 2.5 mm crack extension as a function of the ferrite content for 

centrifugally cast CF-3, CF-8, and CF-8M CASS materials. .............................................62

46. Flow stress ratio Rf of aged CF-3, CF-8, and CF-8M materials at RT and 290°C as a 

function of the normalized aging parameter......................................................................64

47. Comparison of the lower-bound J-R curve at 290°C for aged static-cast CF-8M 

material estimated by using the NUREG/CR-4513, Rev. 1, expressions, with the 

SAW data used to develop ASME Section XI, Subsection IWB-3640 evaluations............69

48. Comparison of the lower-bound J-R curve at 290°C for aged static-cast CF-8M 

material estimated by using the updated expressions, with the fracture toughness of 

SAW data used to develop ASME Section XI, Subsection IWB-3640 evaluations............71
x

49. Comparison of the lower-bound J-R curve at 290°C for aged centrifugally cast 

CF-8M estimated by using the updated expressions, with the fracture toughness of 

SAW data used to develop ASME Section XI, Subsection IWB-3640 evaluations............71

50. Change in fracture toughness JIc as a function of neutron exposure for LWR 

irradiated austenitic SSs...................................................................................................77

51. Fracture toughness JIc as a function of neutron exposure for SSs....................................78

52. Change in fracture toughness JIc for a select data set as a function of neutron 

exposure for LWR irradiated austenitic SSs. ....................................................................79

53. Fracture toughness J-R curves for sensitized Type 304 SS, weld HAZ materials of 

Type 304 and 304L SS, and CF-8M steel in high-purity water at 289°C. ..........................80

54. Fracture toughness JIc of irradiated austenitic SSs and welds as a function of test 

temperature......................................................................................................................80

55. Fracture toughness J-R curves for irradiated specimens of Type 304L SAW HAZ in 

air and NWC BWR environment.......................................................................................81

56. Fracture toughness J-R curves for thermally aged and irradiated CF-8M steel.................82

57. Change in initiation toughness JIc of (a) wrought austenitic SSs and (b) CASS 

materials and weld metals as a function of neutron exposure...........................................84

58. Plots of fracture toughness JIc values as a function of neutron dose for (a) austenitic 

SS welds, (b) CASS materials, and (c) austenitic SS HAZ. ..............................................85

59. Coefficient C of the J-R curve as a function of neutron dose for CASS materials. 

Solid line represents the lower-bound C values proposed in NUREG/CR-7027................87

60. Fracture toughness J2.5 values as a function of neutron dose for CASS materials. ..........88

61. Comparison of the fracture toughness JIc, coefficient, and J2.5 value obtained in air 

and LWR environment at 290–320°C of CF-3, CF-8, and CF-8M materials in the 

unaged and aged as well as unirradiated and irradiated conditions..................................90
xi

LIST OF TABLES

1. Screening criteria for thermal-aging susceptibility of CASS CF-3, CF-8, and CF-8M 

materials. ...........................................................................................................................5

2. Chemical composition, ferrite content, and kinetics of thermal embrittlement for 

various heats of CASS materials......................................................................................24

3. Primary circuit piping CASS material in Westinghouse plants. .........................................39

4. The lower-bound J-R curve at RT and 290–320°C for aged CASS materials. ..................56

5. Updated screening criteria for thermal-aging susceptibility of CASS CF-3, CF-8, and 

CF-8M materials...............................................................................................................63

6. LWR core internal components made of CASS materials and maximum neutron 

dose after 60 years of service. .........................................................................................74

7 Fracture toughness J-R curve data on irradiated CASS CF-3, CF-8, and CF-8M 

materials in air and LWR environments............................................................................86

xiii

EXECUTIVE SUMMARY

Cast austenitic stainless steels (CASSs) used in reactor pressure-boundary components —

such as valve bodies, pump casings, primary coolant piping, and some reactor core internal 

components of light water reactors (LWRs) — suffer a loss in fracture toughness due to thermal 

aging after many years of service at temperatures in the range of 280–320°C (≈535–610°F). 

Thermal aging of CASS materials at these temperatures causes an increase in hardness and 

tensile strength and a decrease in ductility, impact strength, and fracture toughness of the 

material. The Charpy transition curve also shifts to higher temperatures. In addition, for CASS 

materials used in reactor core support structures and core internals components, exposure to 

neutron irradiation for extended periods leads to further degradation of their fracture properties 

due to radiation hardening and radiation-induced segregation (RIS). In such instances, a 

fracture mechanics methodology, such as linear-elastic fracture mechanics (LEFM) or elasticplastic fracture mechanics (EPFM) is needed for analyzing structural integrity and developing 

inspection guidelines. Therefore, an assessment of the degradation of mechanical properties 

due to thermal and irradiation embrittlement is required to evaluate the performance of CASS 

components during prolonged exposure to service temperatures and environments.

Investigations at Argonne National Laboratory (ANL) and elsewhere have shown that thermal 

embrittlement of CASS components can occur during the reactor design lifetime of 40 years. 

Different grades and heats of CASS materials exhibit varying degrees of thermal embrittlement. 

In general, the low carbon (low C) CF-3 materials are the most resistant to thermal 

embrittlement, and the Mo-bearing, high C CF-8M materials are the least resistant. 

Embrittlement of CASS materials can result in brittle fracture associated with cleavage and/or 

twinning of the ferrite phase and separation of the ferrite/austenite phase boundary. The 

amount of cleavage increases with increases in the degree of thermal embrittlement or 

decreases in test temperature. At high temperatures (>500°C), twinning appears to plays an 

important role in brittle failure of ferrite. The thermal aging of CASS materials at temperatures

<500°C (<932°F) leads to (a) the formation of a Cr-rich α' phase by spinodal decomposition and 

by precipitation and growth of α', and (b) the nucleation and growth of additional phases such as 

α', Ni- and Si-rich G phase, M23C6 carbides, and γ2 austenite. The formation of the α' phase 

provides the strengthening mechanisms that increase strain hardening and local tensile stress. 

Consequently, the critical stress level for brittle fracture is attained at higher temperatures. 

Predominantly brittle failure occurs when either the ferrite phase is continuous (e.g., in CASS

material with a high ferrite content) or the ferrite/austenite phase boundary provides an easy 

path for crack propagation (e.g., in high-C grades of cast steel with large phase-boundary 

carbides). Consequently, the amount, size, and distribution of the ferrite phase in the duplex 

structure along with the presence of phase-boundary carbides are important parameters in 

controlling the degree or extent of thermal embrittlement. 

NUREG/CR-4513, Rev. 1, presented a procedure and correlations for estimating the Charpyimpact energy and fracture toughness J-R curve of CASS components under LWR operating 

conditions from material information readily available in certified material test records (CMTRs). 

In this report, the procedure and correlations have been updated by using a much larger 

fracture toughness database for thermally aged CASS materials. The applicability of the 

methodology has also been extended to materials with a ferrite content of up to 40%. In 

addition, for CASS materials used in the reactor core support structure and core internals 

components, guidance is provided for evaluating the combined effects of thermal and neutron 

embrittlement. The procedure for estimating the change in tensile stress, including the 

Ramberg/Osgood parameters for strain hardening, is also presented. 
xiv

The fracture toughness of a specific CASS material is estimated from the extent and kinetics of 

thermal embrittlement. The extent of thermal embrittlement (i.e., the degradation of mechanical 

properties) is characterized by the room-temperature (RT) Charpy-impact energy. A correlation 

for the extent of thermal embrittlement at “saturation” (i.e., the minimum impact energy that 

would be achieved for the material after long-term aging) is given in terms of the chemical 

composition. The extent of the change in RT Charpy-impact energy as a function of the time 

and temperature of reactor service is estimated from the extent of change in RT Charpy-impact 

energy at saturation and from the correlations describing the kinetics of embrittlement, which 

are also given in terms of chemical composition. 

The fracture toughness J-R curve for the material is then obtained from the correlation between 

the fracture toughness parameters and the RT Charpy-impact energy. The tensile yield and

flow stresses and Ramberg/Osgood parameters for tensile strain hardening are estimated from 

the flow stress of the unaged material and the kinetics of embrittlement. The fracture toughness 

JIc and tearing modulus can then be determined from the estimated J-R curve and tensile flow 

stress. A common lower-bound J-R curve for CASS materials of unknown chemical 

composition is also defined for a given material specification, ferrite content, and temperature.

The differences between the methodology presented in this report and that described in 

NUREG/CR-4513, Rev. 1, are as follows:

(i) For CF-8M materials, the correlation between the RT Charpy-impact energy and 

material parameter φ has been revised. 

(ii) For CF-8M materials, the correlations between the RT Charpy-impact energy and 

coefficient C of the J-R curve at RT and 290–320°C have been extended to include 

CASS materials with a ferrite content of up to 40%. 

(iii) The correlations between the RT Charpy-impact energy and exponent “n” of the J-R 

curve at RT and 290–320°C have been revised. 

(iv) The minimum fracture toughness J-R curve for centrifugally cast CASS materials, has 

been revised. 

(v) New lower-bound curves that correlate the saturation RT Charpy-impact energy with

ferrite content for CF-3, CF-8, and CF-8M materials are presented. 

(vi) Guidance is provided for estimating the lower-bound fracture toughness curves for 

CASS materials used in the reactor core support structures and core internals 

components. 

These updated expressions for estimating fracture toughness of CASS materials during reactor 

service have the following impact on the criteria proposed by NRC for determining the 

susceptibility of various categories of CASS components to thermal aging embrittlement. Based 

on the casting process and whether the materials contains low Mo (0.5 wt.% max.) or high Mo 

(2.0–3.0 wt.%), the proposed criteria specify the ferrite content above which the material would 

be susceptible to thermal embrittlement. 

• The criteria for low-Mo CF-3 and CF-8 materials have not changed. All centrifugally cast 

materials and static cast materials containing ≤20% ferrite are not susceptible to thermal 

embrittlement. Only static cast materials containing >20% ferrite are potentially 

susceptible. 
xv

• The criteria for CF-8M materials depend on whether the material contains ≥10 wt.% Ni. 

- The criterion for static cast CF-8M materials containing <10% Ni has not changed. 

Static cast materials with ≤14% ferrite are not susceptible and with >14% ferrite are 

potentially susceptible. 

- The criterion for centrifugally cast CF-8M materials containing <10% Ni has been 

revised. The threshold value of ferrite content has been decreased from 20% to 19% 

ferrite. Centrifugally cast materials with ≤19% ferrite are not susceptible and with 

>19% ferrite are potentially susceptible to thermal embrittlement. 

- The criterion for static cast CF-8M materials containing ≥10% Ni has been revised. 

The threshold value of ferrite content has been decreased from 14% to 11% ferrite. 

Static cast materials with ≤11% ferrite are not susceptible and with >11% ferrite are 

potentially susceptible to thermal embrittlement. 

- The criterion for centrifugally cast CF-8M materials containing ≥10% Ni has been 

revised. The threshold value of ferrite content has been decreased from 20% to 13% 

ferrite. Centrifugally cast materials with ≤13% ferrite are not susceptible and with 

>13% ferrite are potentially susceptible to thermal embrittlement. 

The methodology presented in this NUREG/CR report is only applicable to service times that 

are equivalent to 10,000 h at 400°C. This corresponds to 

• ≥125 effective full power years (efpy) at 290°C for CF-8/CF-3 materials, 

• ≥30 efpy at 320°C for CF-8/CF-3 and ≥15 efpy for CF-8M materials used within primary 

pressure boundary components, and 

• ≥15 efpy at 350°C for CF-8/CF-3 materials used in the reactor core internals. 

Additional long-term aging data are needed to estimate fracture properties for longer service 

times. Furthermore, this methodology may not be applicable for CF-8M materials with more 

than a trace amount of Nb, particularly for materials containing >15% ferrite. The methodology 

also does not consider the effect of reactor coolant environment on fracture toughness. Limited 

data indicate significant effect of environment, particularly at low temperatures (e.g., shutdown 

water chemistry at 54°C). In addition, the existing fracture toughness data on LWR-irradiated 

CF-3 and CF-8 materials is inadequate to accurately establish the lower-bound J-R curves for 

these materials as a function of neutron dose.

xvii

ACKNOWLEDGMENTS

The author thanks Sébastien Saillet of EdF for providing valuable information and helpful 

discussions. The author also thanks Tim Griesbach of Structural Integrity Associates, Inc. (SIA)

for his comments and help in obtaining relevant data.

xix

ABBREVIATIONS AND ACRONYMS

AMP aging management program

APFIM atom probe field ion microscopy

ASME American Society of Mechanical Engineers

ASTM American Society for Testing and Materials

AWS American Welding Society

B&W Babcock and Wilcox

BWR boiling water reactor

C Carbon

CASS cast austenitic stainless steels

CE Combustion Engineering

CEA control element assembly 

CEGB Central Electricity Generating Board

CMTR certified material test record

Cr Chromium 

CRGT control rod guide tube

CT compact tension

CTOD crack tip opening displacement

CW cold-worked

DO dissolved oxygen

dpa displacement(s) per atom

EdF Electricité de France

efpy effective full power year(s)

EMA Etude des Matériaux (EDF formula for ferrite content prediction)

EPFM elastic-plastic fracture mechanics

EPRI Electric Power Research Institute

Fe Iron

FN ferrite number

FRA Framatome (now Areva)

GE General Electric

GF George Fischer

GMAW gas metal-arc weld

GTAW gas tungsten-arc weld

HAZ heat-affected zone

JAPEIC Japan Power Electric Engineering and Inspection Corp.

JNES Japan Nuclear Energy Safety Organization

J-R J-integral resistance

ksi kilo pounds per square inch

LEFM linear-elastic fracture mechanics

LPCI low-pressure core injection

LTCP low-temperature crack propagation
xx

LWR light water reactor

MEA Materials Engineering Associates, Inc.

MHI Mitsubishi Heavy Industries

Mn Manganese

Mo Molybdenum

MRP Materials Reliability Program

MWe megawatt(s)-electric

N Nitrogen

Nb Niobium

NDT nil-ductility transition

Ni Nickel

NP National Power

NPP nuclear power plant

NRC U.S. Nuclear Regulatory Commission

NWC normal water chemistry

P Phosphorous

PFM probabilistic fracture mechanics

ppb part(s) per billion

ppm part(s) per million

PWR pressurized water reactor 

RIS radiation-induced segregation

RT room temperature (25°C) 

S Sulfur

SANS small-angle neutron scattering

SAW submerged arc weld

SCC stress corrosion cracking

SE(B) single-edge bend

Si Silicon

SIA Structural Integrity Associates, Inc.

SMAW shielded metal arc weld

SS stainless steel

TEM transmission electron microscopy

TG transgranular

Ti Titanium

TWI The Welding Institute

WH Westinghouse
xxi

NOMENCLATURE

a crack length

C coefficient of the power-law J-R curve

Creq chromium equivalent for the material 

CV room temperature “normalized” Charpy-impact energy; i.e., Charpy-impact energy per 

unit fracture area at any given service and aging time (J/cm2). The fracture area for a 

standard Charpy V-notch specimen (ASTM Specification E 23) is 0.8 cm2. The value 

of the impact energy in J has been divided by 0.8 to obtain the “normalized” impact 

energy in J/cm2.

CVint initial room temperature “normalized” Charpy-impact energy of a material; i.e., unaged 

material (J/cm2)

CVsat room temperature “normalized” Charpy-impact energy of a material at saturation. It 

represents a “quasi-saturation” value of RT (i.e., 25°C) impact energy achieved by the 

material after long-term aging, primarily due to spinodal decomposition of the ferrite. 

The impact energy continues to decrease further during aging, but at much slower 

rate. 

da increment in crack length

dJ increment in J integral 

E elastic modulus

F ferrite content 

J J integral, a mathematical expression used to characterize the local stress-strain field 

at the crack tip region (parameter J represents the driving force for crack propagation)

Jd deformation J integral

JIc value of J near the onset of crack extension

JM modified J integral 

ksi kilo pound per square inch

K stress intensity factor

KIc critical stress intensity factor

KJc equivalent critical stress intensity factor

m constraint factor for the power-law J-R curve

M constraint factor, which relates J to the crack tip opening displacement (CTOD)

MPa mega Pascal

n exponent of the power-law J-R curve

n1 Ramberg-Osgood parameter

Nieq nickel equivalent for the material

P aging parameter; i.e., the log of the time of aging at 400°C

Q activation energy for the process of thermal embrittlement (kJ/mole)

R gas constant 

Rf the ratio of the tensile flow stress of aged and unaged CASS (σfaged/σfunaged)

Ry the ratio of the tensile yield strength of aged and unaged CASS (σyaged/σyunaged)

t time (h)

T tearing modulus or temperature
xxii

α shape factor of the curve for the change in room-temperature Charpy-impact energy 

with the time and temperature of aging

α1 Ramberg-Osgood parameter

β half the maximum change in room temperature Charpy-impact energy 

γ gamma phase (i.e., austenite)

δc ferrite content calculated from the chemical composition of a material (%) 

∆ crack extension 

ε strain

φ material parameter 

σ stress

σf flow stress, defined as the average of yield and ultimate strength

σ0 an arbitrary reference stress

σu ultimate strength

σy yield strength

θ aging behavior at 400°C; i.e., the log of the time to achieve the β reduction in impact 

energy at 400°C

υ Poisson ratio

In this report, all values of impact energy were normalized with respect to the actual crosssectional area of the Charpy-impact specimen. Thus, for a standard Charpy V-notch specimen 

per ASTM Specification E 23 (i.e., 10 × 10-mm cross section and 2-mm V notch), the impact 

energy value in J was divided by 0.8 cm2 to obtain the impact energy in J/cm2. The impact 

energies obtained for sub-size specimens were normalized with respect to the actual crosssectional area, and appropriate correction factors were applied to account for size effects. 

Similarly, impact energies from other standards, such as the 2.5-mm U-notch specimens used 

for the Charpy VSM values in Switzerland or the 5-mm U-notch specimens used for the KCU 

values in France, were converted to a Charpy V-notch value by appropriate correlations.

SI units of measurements are used in this report. Conversion factors for measurements in 

British units are as follows:

To Convert from To Multiply by

in. mm 25.4

J* ft-lb 0.7376

kJ/m2 in.-lb/in.2 5.71015

kJ/mole kcal/mole 0.239

 * When the impact energy is expressed in J/cm2

, first multiply by 0.8 to obtain the impact energy of an ASTM 

standard Charpy V-notch specimen in J. 
1

1 INTRODUCTION

Austenitic stainless steels (SSs) are used extensively as structural alloys in light water reactor 

(LWR) systems, including reactor core internal components, because of their excellent ductility, 

high notch toughness, corrosion resistance, and good formability. In addition, cast austenitic

stainless steel (CASS) materials are used in LWR systems for reactor pressure-boundary 

components, such as valve bodies, pump casings, primary coolant piping, and some reactor 

core internal components. Although austenitic SSs are completely austenitic in the wrought 

condition, CASS materials or welded SSs have a duplex structure consisting of austenite and 

ferrite phases. The ferrite phase provides additional benefits; it increases tensile strength and 

improves resistance to stress corrosion cracking (SCC). 

However, CASS materials, because they have a duplex structure, are susceptible to thermal 

embrittlement after extended operation at reactor operating temperatures for core internals,1–32

typically 282°C (540°F) for boiling water reactors (BWRs), 288–327°C (550–621°F) for 

pressurized water reactor (PWR) primary coolant piping, and 343°C (650°F) for PWR 

pressurizers. In addition, exposure to neutron irradiation for extended periods changes the 

microstructure (radiation hardening) and microchemistry (radiation-induced segregation or RIS) 

of wrought and cast austenitic SSs and degrades their fracture properties.33–47 In such 

instances, a fracture mechanics methodology, such as linear-elastic fracture mechanics (LEFM) 

or elastic-plastic fracture mechanics (EPFM), is needed for analyzing structural integrity and 

developing inspection guidelines. EPFM involves the J integral-resistance (J-R) curve approach 

where failure is caused by plastic deformation. The J integral is a mathematical expression

used to characterize the local stress-strain field at the crack tip region (parameter J represents 

the driving force for crack propagation), and the J-R curve characterizes the resistance of the 

material to stable crack extension. The fracture toughness of such materials is represented by 

fracture mechanics parameters such as JIc, the value of J near the onset of crack extension, 

and T, the tearing modulus, which characterizes the slope of the J-R curve:

, (1)

where the first term represents the slope of the J-R curve at aIc, E is the elastic modulus, a is 

the crack length, and σf is the flow stress defined as the average of the yield strength (σy) and 

ultimate strength (σu). The LEFM methodology is used where failure involves negligible plastic 

deformation. The fracture toughness of such materials is represented by parameter KIc (i.e.,

critical stress intensity factor, a plane strain fracture toughness measure), which characterizes 

the resistance of the material to unstable crack extension. Since JIc and KIc have different units, 

it is often convenient to represent JIc in terms of a parameter KJc, which has the units of the 

stress intensity factor and is determined from the JIc value using the relationship:

KJc = (E ́JIc)1/2, (2)

where the normalized elastic modulus is given by E ́ = E/(1 - υ2), E is the elastic modulus, and υ

is the Poisson ratio. Only in cases where LEFM is applicable, is KJc equal to the critical stress 

intensity. 

The fracture toughness of austenitic SSs has been divided into three broad categories.48 

Category III corresponds to materials with a high toughness and with JIc that is above 150 kJ/m2

(857 in.-lb/in.2). In these materials, fracture occurs after stable crack extension at stresses well 
2

above the yield strength. Category II corresponds to materials with intermediate toughness and 

with JIc in a range of 30–150 kJ/m2 (171–857 in.-lb/in.2). In Category II materials, fracture 

occurs by stable or unstable crack extension at stress levels close to the yield strength. 

Category I corresponds to low-toughness materials with JIc of <30 kJ/m2 (<171 in.-lb/in.2), and 

fracture occurs below the yield strength with little or no stable crack extension. 

Unirradiated and unaged wrought SSs and CASS materials fall in Category III. For these 

materials, the fracture toughness JIc values for Type 304 and 316 SS at temperatures up to 

125°C (257°F) vary between 169 and 1660 kJ/m2 (965 and 9479 in.-lb/in.2), with a median value 

of 672 kJ/m2 (3,837 in.-lb/in.2).48 The JIc values at 400–550°C (752–1022°F) are approximately 

35% lower, with a median value of 421 kJ/m2 (2404 in.-lb/in.2). Fracture in such high-toughness 

materials is by the nucleation and coalescence of microvoids and is characterized by dimpled 

fracture morphology. Typically, CASS materials also exhibit ductile fracture at temperatures up 

to 550°C (1022°F), but their fracture toughness is lower than that of the wrought SSs. The 

fracture toughness of CASS material is affected by the density and morphology of secondphase inclusions in the material, and it varies with the casting method. For example, static cast 

products have a slightly lower fracture toughness than the centrifugally cast pipes. 

Extensive studies have been conducted on the thermal embrittlement of CASS materials at 

Georg Fischer Co. (GF),1 Westinghouse (WH),2 The Welding Institute (TWI),6 Framatome 

(FRA),7–9 Electric Power Research Institute (EPRI),10 Argonne National Laboratory (ANL),

12–18

Central Electricity Generating Board* (CEGB),21 Electricité de France (EdF),22–27 Mitsubishi 

Heavy Industries (MHI),28–31 and Japan Nuclear Energy Safety Organization (JNES).32 In the 

ANL study, a procedure and correlations were developed for estimating the Charpy-impact 

energy and fracture toughness J-R curve of CASS components under LWR operating conditions 

from material information readily available in certified material test records (CMTRs). The 

methodology for estimating the fracture toughness of aged CASS materials was described in 

NUREG/CR-4513, Rev. 1.16 The ANL estimation scheme is applicable to Grades CF-3, CF-3A, 

CF-8, CF-8A, CF-3M, and CF-8M of CASS materials within American Society for Testing and 

Materials (ASTM) Specification A351 for austenitic castings for pressure-retaining parts and 

Specification A451 for centrifugally cast austenitic SS pipes for high-temperature service. The 

fracture toughness of a specific CASS material is estimated from the extent and kinetics of 

thermal embrittlement. 

The extent of thermal embrittlement (i.e., the degradation of mechanical properties) is 

characterized by the room temperature (RT), “normalized” Charpy-impact energy (CV or Charpyimpact energy per unit fracture area). A correlation for the change in RT Charpy-impact energy 

at “saturation” (i.e., the minimum Charpy-impact energy that would be achieved for the material 

after long–term aging) is given in terms of the material chemical composition. The extent of the 

change in RT Charpy-impact energy as a function of the time and temperature of reactor service 

is estimated from the change the RT Charpy-impact energy at saturation and the correlations 

describing the kinetics of embrittlement. The kinetics of embrittlement are given in terms of the 

material composition and the initial Charpy-impact energy, CVint, of the material in the unaged 

condition. If CVint is not known, a typical value of 200 J/cm2 (118 ft-lb) is assumed. 

The fracture toughness J-R curve for the material is then obtained from the correlation between 

the fracture toughness parameters and RT Charpy-impact energy. A common lower-bound J-R 

curve for CASS materials of unknown chemical composition is also defined for a given material 

specification, ferrite content, and temperature. Tensile yield and flow stresses and 

Ramberg/Osgood parameters for tensile strain hardening are estimated from the flow stress of 

 *The British electricity industry from 1957 to 1990 when it was privatized.
3

the unaged material and the kinetics of embrittlement.18 Examples of estimating mechanical 

properties of CASS components during reactor service is presented. The significant features of 

the methodology proposed in NUREG/CR-4513, Rev. 1,16 are as follows:

• The correlations are based on a database consisting of about 80 compositions of CASS 

materials and of mechanical-property data (mostly Charpy V-notch impact energy) on 

materials aged up to 58,000 h at 290–350°C (554–662°F). 

• The saturation RT impact energy CVsat is estimated from two different correlations. In 

general, the two methods result in comparable estimates for most materials. However, 

for a few heats one or the other set of expressions results in estimates that are more 

accurate. It is likely that minor differences in the composition and microstructure of the 

ferrite caused by differences in the production heat treatment and possibly in the casting 

process influence CVsat values. These factors are difficult to quantify from the existing 

database. To ensure that the estimates are either accurate or conservative for all heats

of CASS materials within ASTM Specification A351, the lower of the two estimated 

values is used for estimating the fracture properties. 

• Separate correlations are proposed for estimating the saturation RT impact energy CVsat

for low-Mo (maximum 0.5 wt.%) CF-3 and CF-8 materials and high-Mo (2.0 to 3.9 wt.%) 

CF-8M materials; also, for the latter, separate correlations are proposed for materials 

containing <10 wt.% Ni and those containing ≥10 wt.% Ni.

• Separate correlations are also proposed for estimating fracture toughness J-R curves for 

static cast and centrifugally cast materials; the fracture toughness of the latter is 

considered superior.

• The methodology also includes correlations for estimating the yield and flow stresses 

and Ramberg/Osgood parameters for tensile strain hardening of aged CASS materials 

from the initial tensile properties and the kinetics of thermal embrittlement.

The criteria used in developing the NUREG/CR-4523, Rev. 1, correlations ensure that the 

estimated mechanical properties are either accurate or somewhat conservative for compositions 

of CASS materials within ASTM Specification A351. The correlations do not consider the 

effects of metallurgical differences that can arise from differences in production heat treatments 

or casting processes; therefore, they may be conservative for some CASS materials. 

Mechanical properties are expressed in SI units (see Nomenclature for units of measure and for 

conversion factors for British units). However, the methodology in NUREG/CR-4513, Rev. 1, 

has the following limitations. 

1. The correlations may yield nonconservative estimates of the fracture toughness J-R curve 

for compositions of static-cast CF-8M steel that are very sensitive to thermal aging. These 

compositions consist of static-cast CF-8M materials for which the estimated value of the RT 

Charpy-impact energy CVsat is less than 25 J/cm2 (15 ft-lb). Typically, these compositions 

contained 25% or more ferrite. The thermal embrittlement data on CASS materials that 

were available at the time NUREG/CR-4513, Rev. 1, was published were not adequate for

accurately establishing the correlations between the RT Charpy-impact energy and fracture 

toughness parameters for CVsat values less than 25 J/cm2.

2. Furthermore, the methodology is not applicable for CASS materials that may contain a 

significant amount of Nb content (i.e., more than 0.05 wt.%). An acceptable level of Nb 

content was not defined in NUREG/CR-4513 Rev. 1. The ASTM Specification A351 for CF8M cast material also does not specify a maximum amount of Nb in the casting; but typically, 

these materials contain less than 0.05 wt.% Nb. 
4

3. For CASS materials used in reactor core support structures and core internal components, 

the combined effect of thermal aging and neutron irradiation embrittlement was also not 

discussed in the NUREG/CR-4523, Rev. 1, report. 

The results of NUREG/CR-4513, Rev. 1, indicate that the lower-bound fracture toughness of 

thermally aged CASS materials is similar to that of submerged arc welds (SAWs) of austenitic 

SSs. Based on these results, the NRC staff accepted the use of the SAW flaw evaluation 

procedures in IWB3640 of Section XI of the American Society of Mechanical Engineers (ASME) 

Code (the 1989 edition of the Section XI Code) to evaluate flaws in thermally aged CASS 

materials (with a ferrite content of less than 25%).49 The NRC staff recognized that since this 

conclusion is based on the lower-bound fracture toughness of aged CASS materials, in some 

instances, utilities might estimate component-specific fracture toughness by using procedures 

developed by ANL on a case-by-case fracture mechanics flaw evaluation. 

In addition, based on the results of NUREG/CR-4513, Rev. 1, the industry proposed screening 

criteria in EPRI TR-106092 to determine if a specific component should be inspected due to its 

potential susceptibility to thermal aging.50 The EPRI report uses a deformation J value of 

255 kJ/m2 (1450 in.-lb/in.2) at a crack depth of 2.5 mm (0.1 in.) (i.e., J2.5 value) to differentiate 

between a nonsignificant and a potentially significant reduction in fracture toughness for fully 

aged CASS material. Flaw tolerance evaluations, described in Appendices A and B of 

EPRI TR-106092 demonstrate that a material toughness of 255 kJ/m2 adequately protects 

against a loss of structural integrity in CASS components. 

The NRC staff reviewed the EPRI TR-106092 report and other industry submittals addressing 

thermal embrittlement of CASS materials and developed a position for managing the 

degradation of fracture properties of thermally aged CASS materials.51 The staff found that 

Appendices A and B of the EPRI report provide an acceptable justification that 255 kJ/m2 is an 

acceptable screening value to use in differentiating between a nonsignificant and a potentially 

significant reduction in fracture toughness of aged CASS components. The staff compared the 

J2.5 values taken from the saturated lower-bound J-R curves as well as the J2.5 values from the 

experimental data with the screening value of 255 kJ/m2 in order to develop screening criteria 

for determining the susceptibility of various categories of CASS components to thermal aging. 

Table 1 presents the criteria that are based upon the Mo content, casting process, and ferrite 

content of the material. The same screening criteria for thermal embrittlement of CASS 

materials have also been proposed by industry.43 The criteria are applicable to all primary 

pressure boundary components constructed from SA-351 Grades CF-3, CF-3A, CF-8, CF-8A, 

and CF-8M, with service conditions above 250°C (482°F). Alternately, components can be 

considered as "potentially susceptible" without considering such screening. The details of the 

criteria are as follows:51

• For high Mo static castings, materials with ferrite levels >14% are considered potentially 

susceptible to thermal embrittlement. Materials with ferrite content ≤14% have adequate 

fracture toughness (i.e., the J2.5 values are above 255 kJ/m2). 

• For high Mo centrifugal castings, materials with ferrite levels >20% are considered 

potentially susceptible, and those with ≤20% ferrite have adequate fracture toughness.

• For low Mo static castings, materials with ferrite levels >20% are considered potentially 

susceptible to thermal embrittlement. However, as discussed later, the J2.5 values for 

CASS materials with up to 40% ferrite are well above the screening value of 255 kJ/m2. 

• For low Mo centrifugal castings, none of the CASS materials are considered susceptible 

to thermal embrittlement. The J2.5 values are well above 255 kJ/m2 for all materials.
5

Table 1. Screening criteria for thermal-aging susceptibility of CASS CF-3, CF-8, and 

CF-8M materials (Ref. 51).

Mo Content (wt.%) Casting Method Ferrite Content (%) Susceptibility Determination

High (2.0–3.0) Static ≤14 Not susceptible

>14 Potentially susceptible

Centrifugal ≤20 Not susceptible

>20 Potentially susceptible

Low (0.5 max.) Static ≤20 Not susceptible

>20 Potentially susceptible

Centrifugal All Not susceptible

The NRC staff position51 also recognized that for reactor vessel internal components fabricated 

from CASS materials, the concurrent exposure to high neutron fluence levels can result in a 

combined effect wherein the service-degraded fracture toughness is reduced from the levels 

predicted independently for either thermal aging or neutron irradiation alone. Therefore, reactor 

vessel internal components that are determined to be subject to thermal embrittlement require 

additional consideration of the neutron fluence of the component to determine the full range of 

degradation mechanisms applicable for the component. 

The component-specific evaluation looks first at the neutron fluence of the component. If the 

neutron fluence exceeds 1x1017 n/cm2 (E>1 MeV), a mechanical loading assessment would be 

conducted for the component.51 This assessment will determine the maximum tensile loading 

on the component during ASME Code Level A, B, C and D conditions. A supplemental 

inspection is not required for the component if the loading is compressive or low enough to 

preclude fracture of the component. Failure to meet this criterion would require continued use 

of the supplemental inspection program.

If the neutron fluence is less than 1x1017 n/cm2 (E>1 MeV), an assessment would be made to 

determine if the affected component(s) are bounded by the screening criteria in Table 1. In 

order to demonstrate that the screening criteria are applicable to reactor vessel internal 

components, a flaw tolerance evaluation specific to the reactor vessel internal components 

would be required similar to that provided in EPRI TR-106092.51 If the material is determined to 

be "potentially susceptible," then a supplemental examination is required on those susceptible 

components determined to be limiting from the standpoint of thermal aging susceptibility (e.g., 

Mo content, δ-ferrite content, casting process, and operating temperature), and cracking 

susceptibility (applied stress level, operating time and environmental conditions). No 

inspections or evaluations are required if the material is determined not susceptible. The 

threshold neutron dose above which an assessment of the neutron embrittlement and its 

effect on component design is needed has been updated in Section 5.3.1.1 of this report.

The NRC staff further proposed51 that if a particular heat of CASS material is found or assumed 

"potentially susceptible" and subject to plausible degradation (e.g., thermal fatigue), aging 

management can be accomplished through volumetric examination or a plant/componentspecific flaw tolerance evaluation. The volumetric examination should be performed on the 

base material of the heat, with the scope of the inspection covering the portions determined to 

be limiting from the standpoint of the applied stress level, operating time and environmental 

considerations. Alternately, a plant/component-specific flaw tolerance evaluation using the 

specific geometry and stress information can be used to demonstrate that the thermally 

embrittled material has adequate toughness.
6

Furthermore, based on Lee et al.,49 flaws detected in CASS components should be evaluated in 

accordance with the applicable procedures of IWB-3500 in Section XI of the ASME Code. If the 

delta ferrite content does not exceed 25%, then flaw evaluation would be in accordance with the 

principles associated with IWB-3640 procedures for SAW, disregarding the Code restriction of 

20% delta ferrite in IWB-3641(b)(1) (of the 1989 edition of the Code). If the material is 

"potentially susceptible," and the delta-ferrite content exceeds 25%, then flaw evaluation would 

be on a case-by-case basis using fracture toughness data supplied by the licensee, such as that 

published by Jayet-Gendrot, et al.24 

Since the time NUREG/CR-4513 Rev. 1 was published and the NRC staff developed a position 

for managing the degradation of the fracture properties of thermally aged CASS materials, the 

industry has also published a few topical reports describing a methodology for managing the 

structural integrity of CASS components during LWR service. EPRI 1016236 provided a 

preliminary methodology for the flaw tolerance evaluation, which when used in concert with 

inspection techniques being developed by EPRI can be used for the long-term management of 

CASS piping in the nuclear industry.52 The EPRI 1024966 report applies a probabilistic fracture 

mechanics (PFM) methodology for the evaluation of depths of part-circumferential cracks in fully 

aged CASS piping that would fail with a given probability when specified loads are applied.53 

The PFM method relies on the key elements of a deterministic analysis but also incorporates 

the inherent uncertainties in these parameters. The methodology is based on the data and 

correlations developed in NUREG/CR-4513, Rev. 1,16 for fracture toughness and NUREG/CR614218 for tensile properties. 

The EPRI 1024966 report also provides a technical basis for management of thermal aging and

reliability of CASS piping in PWRs. The results indicated that CASS piping components are 

highly flaw-tolerant, even in the thermally aged condition. ASME Code Case N-838 was also 

developed based on the PFM methodology for evaluating the effects of thermal aging and 

uncertainties in the CF-8M CASS piping material properties. The technical basis for the flaw 

tolerance evaluation of CASS piping to support the Code Case is presented in a Materials 

Reliability Program (MRP) report, MRP-362.54 The combined effects of thermal and neutron 

embrittlement of CASS materials for PWR and BWR core internals are also discussed in 

industry reports MRP-27655 and BWRVIP-234,56 respectively.

In this report, the methodology presented earlier in NUREG/CR-4513, Rev. 1, has been 

updated. The revised methodology is applicable to CASS materials containing up to 40% ferrite 

and for operating times equivalent to only 10,000 h at 400°C. This corresponds to

• ≥125 effective full power years (efpy) at 290°C for CF-8/CF-3 materials, and 

• ≥30 efpy at 320°C for CF-8/CF-3 and ≥15 efpy for CF-8M materials used within primary 

pressure boundary components, and 

• ≥15 efpy at 350°C for CF-8/CF-3 materials used in the reactor core internals.* 

The combined effects of thermal and neutron embrittlement on the loss of fracture toughness of 

these materials have also been included. The lower-bound value of fracture toughness —

defined in terms of the JIc, C (i.e. the coefficient of the power law J-R curve), or the J value at a 

2.5-mm crack extension — due to thermal and neutron embrittlement is expressed in terms of 

the neutron dose. The details regarding the various CASS materials and the associated 

Charpy-impact energy, tensile property and fracture toughness J-R curve information included 

in the database evaluated for this study are compiled and tabulated in Appendix A. 

 * A higher temperature is used to include gamma-heating effect. 
7

2 THERMAL EMBRITTLEMENT OF CAST

STAINLESS STEELS

It has been known that binary Fe-Cr alloys and ferritic SSs are susceptible to severe 

embrittlement when exposed to temperatures in the range of 300 to 500°C (572 to 932°F).57–59 

The potential for significant embrittlement of CASS duplex materials, has been confirmed by 

studies at ANL12–18 and elsewhere1,2,6–10,21–32 on materials that were aged at temperatures of

285 to 450°C (545 to 842°F) for times up to 118,000 h (≈13.5 yr). The results indicate that 

thermal aging of CASS materials (ASTM Specification A-351 for Grades* CF-3, CF-3A, CF-8, 

CF-8A, and CF-8M) at 250–350°C (482–662°F) (a) increases their hardness and tensile 

strength; (b) decreases their ductility, impact strength, and fracture toughness; and (c) shifts the 

Charpy transition curve to higher temperatures. Different grades and heats of CASS exhibit 

varying degrees of thermal embrittlement. The low-carbon (low-C) CF-3 materials are the most 

resistant to thermal embrittlement, and the Mo-bearing, high-C CF-8M materials are the least 

resistant. Ferrite morphology has a strong effect on the degree or extent of embrittlement, 

whereas small changes in the material composition significantly alter the kinetics of 

embrittlement. In addition, as the results of studies on the kinetics of thermal aging 

demonstrate, thermal embrittlement of CASS materials can occur during the initial 40-year 

license period for power reactor operation.12 

2.1 Mechanism of Thermal Embrittlement

Fracture of the 300 series austenitic SSs occurs essentially by nucleation, growth, and 

coalescence of microvoids, which results in a dimpled fracture morphology, regardless of the 

test temperature.48 The heat-to-heat variability is due to the differences in the density and 

morphology of inclusions such as carbides, calcium aluminates, and manganese sulfides, which 

serve as nucleation sites for void formation. The large inclusions or inclusion clusters aligned in 

the working direction fail early in the deformation process, thereby resulting in poor fracture 

toughness. In relatively tough materials, microvoids nucleate away from the primary fracture 

plane, and significant plastic deformation is required for void coalescence. 

A similar fracture behavior is also observed in unaged CASS materials; fracture occurs by 

microvoid coalescence. In CASS materials, voids nucleate preferentially within the ferrite 

phase, or at inclusions and phase boundaries.20,22,48 The overall fracture toughness is 

controlled by the density and morphology of the second phase particles and to some extent by 

the volume fraction of ferrite. 

Furthermore, in materials with a duplex structure, the ferrite phase exhibits a ductile-to-brittletransition temperature. The plastic straining capacity of ferrite is substantially decreased at low 

temperatures. However, the ferrite is ductile at RT and higher temperatures. Therefore, in the 

unaged condition, CASS materials exhibit a ductile dimpled fracture. The transition 

temperatures of unaged materials are relatively low. The differences in the transition 

temperature for the various unaged heats and grades of CASS materials are due to the amount 

of ferrite and the differences in the mechanism of brittle fracture. The high-carbon CF-8 or CF8M materials have a higher transition temperature than CF-3 materials because of the presence 

of phase boundary carbides. The carbides weaken the boundaries and lead to premature 

phase boundary separation with little or no strain hardening.12

 *The CF-3A and CF-8A grades represent materials with a high tensile strength. The chemical composition of these 

grades is further restricted within the composition limits of CF-3 and CF-8 in order to obtain a ferrite/austenite ratio 

that results in higher ultimate and yield strengths. In this report, they are considered equivalent to CF-3 and CF-8 

grades.
8

The available data indicate that the fracture toughness of wrought austenitic SSs is strongly 

influenced by specimen orientation.

39 Fracture toughness J-R tests on Type 304 control-rod 

and Type 304L top guide materials irradiated to 4.7–12.0 displacements per atom (dpa) in a 

BWR show lower fracture toughness in the longitudinal direction (T-L orientation)* than in the LT orientation. The lower fracture toughness along the T-L orientation is attributed to the 

presence of stringers. These stringers consisted of long, narrow particles oriented in the rolling 

direction that result in a long, narrow quasi-cleavage structure that is parallel to the crack plane

and thereby accelerates crack advance. When stringers are aligned parallel to the crack 

propagation direction T-L (or C-L) orientation, tear ridges are nucleated ahead of the crack front, 

and the coalescence of these torn ridges results in premature crack advance without extensive 

plastic deformation.39 When stringers are normal to the crack propagation direction (i.e., L-T or 

L-C orientation), microvoids are very deep and equiaxed, which blunts the advancing crack tip, 

and significant plastic deformation is needed for failure. 

The available data also indicate that CASS materials suffer from thermal embrittlement of the 

ferrite during service at 300–450°C (572–842°F) and that the ductile-to-brittle transition 

temperatures shift higher.12–18,48 The time-temperature curves for the formation of various 

phases in thermally aged CASS materials4 are shown in Fig. 1. The results indicate that at 

temperatures above 550°C (1020°F), the embrittlement is largely due to the formation of the 

sigma phase, and that below 500°C (930°F), the precipitation of the α' phase leads to 

embrittlement. The formation of carbides and the chi phase influences mechanical properties in 

the 500–600°C (930–1110°F) temperature range. At reactor operating temperatures of 280–

370°C (535–698°F), thermal aging of CASS materials leads to:

Figure 1. Time-temperature curve for the formation of various 

phases in CASS materials (Ref. 4).

(a) spinodal decomposition of the ferrite into high-Cr α' and low-Cr α regions; 

 *The first letter represents the direction perpendicular to the plane of the crack, and the second letter represents the 

direction of crack advance. For plates, L = longitudinal or rolling direction and T = transverse direction (i.e., 

perpendicular to the rolling direction but not across the plate thickness). For pipes, L = longitudinal or axial direction, 

and C = circumferential direction (across the wall).
9

(b) nucleation and growth of the high-Cr α' phase; 

(c) precipitation of a Ni- and Si-rich G phase, M23C6, and γ2 (austenite); and 

(d) additional precipitation and/or growth of existing carbides at ferrite/austenite phase 

boundaries.5,60–67 

Another mechanism that can cause such behavior is a decrease in the ferrite content of CASS 

materials aged at temperatures above 400°C, particularly CF-8M materials. The metallographic 

data on CF-8 and CF-8M materials indicate significant precipitation of phase boundary carbides 

and/or growth of existing carbides during thermal aging, particularly at 450°C. The precipitation 

of Cr-rich carbides is always accompanied by a decrease in the ferrite content.4 The depletion 

of Cr destabilizes the ferrite phase, leading to ferrite-to-austenite transformation along the phase 

boundary. The growth of austenite into the ferrite grain occurs as cellular precipitation, along 

with the carbides.4 Such transformations can result in an increase in Charpy-impact energy.

A study at EdF on the evolution of thermally aged CASS materials using Charpy U-notch impact 

test specimens indicates that at RT, the brittle transgranular fracture of ferrite takes place 

primarily by cleavage; some twinning is also observed in highly embrittled material.22 Multiple 

cleavage of ferrite islands is observed throughout the material. All the cleavage facets are 

parallel to each other, regardless of the geometry of the individual islands. The percent of 

cleavage increases with increases in the degree of thermal embrittlement or with decreases in 

test temperature. At higher temperatures, although cleavage of the ferrite is reduced, twinning 

appears to play an important role in brittle failure of ferrite. The ferrite/austenite phase boundary 

exhibits a jagged appearance, with very fine lines and straight deformation bands within the 

ferrite islands (most likely slip bands and twins).22 Figure 2 shows deformation twins in a 

Charpy-impact specimen of CF-8 material aged for 30,000 h at 350°C and tested at 290°C. The 

fracture behavior of the austenite also changes from a dimple fracture to shear fracture. The 

presence of a completely embrittled ferrite skeleton promotes the low-energy failure mode of 

ductile shearing or tearing of the austenite ligaments between the islands of ferrite.9 Typically, 

in unaged duplex materials, cavities initiate from the cleavage cracks in the ferrite and not from 

matrix-inclusion decohesions. 

Figure 2.

Deformation twins in a 

Charpy-impact specimen 

of CF-8 material aged for 

30000 h at 350°C and 

tested at 290°C (Ref. 12). 

Another study on microstructural characterization and fracture behavior of unaged and aged 

CF-8M material at RT using Charpy V-notch and fracture toughness CT specimens also showed 
10

similar failure mechanisms.68 At RT, a fully ductile dimple fracture is observed for unaged 

material and material aged up to 40,000 h at 300°C (572°F). Ductile dimple fracture and brittle 

cleavage facets are observed for material aged up to 10,000 h at 350 and 400°C (662 and 

752°F). In addition to these two fracture modes, ferrite/austenite phase boundary separation is 

also observed in materials aged at 450°C (842°F). Phase boundary separation is generally 

observed in high-C CASS materials aged at high temperatures (i.e., 400 or 450°C). 

Fractographic evaluation of both Charpy V-notch and fracture toughness CT specimens shows

similar fracture modes for aged CF8M material. The only difference is that in the CT 

specimens, longer aging times are needed before brittle cleavage fracture is observed. 

Although only RT (i.e., 25°C) tests were conducted in this study, tests at higher temperatures 

are expected to show a larger fraction of ductile dimple fracture and less brittle fracture. 

Thus, severely embrittled CASS materials generally exhibit large areas of brittle transgranular 

fracture of ferrite, linked by ductile shearing or tearing of the austenite ligaments. The degree of 

embrittlement and, thus, the toughness of the material are controlled by the amount of brittle 

fracture. CASS materials with poor toughness and impact strength exhibit a greater fraction of

brittle fracture. For some CASS materials, although a fraction of the material may fail in a brittle 

fashion, the surrounding austenite provides ductility and toughness. Such materials have 

adequate toughness even after long-term aging. A predominantly brittle failure occurs when 

either the ferrite phase is continuous (e.g., in cast material with a large ferrite content) or the 

ferrite/austenite phase boundary provides an easy path for crack propagation (e.g., in high-C 

grades of cast steel with large phase-boundary carbides). For CF-8M materials with lacy ferrite 

morphology, ferrite contents of about 10% or more can provide a continuous ferrite phase.* 

Consequently, the amount, size, and distribution of the ferrite phase in the duplex structure and 

the presence of phase-boundary carbides are important parameters in controlling the degree or 

extent of thermal embrittlement.

Cleavage of ferrite occurs when the local tensile stress reaches the critical cleavage fracture 

stress. At low temperatures, (i.e., high values of yield strength), cleavage cracks nucleate in the 

ferrite in the plastic zone near the notch tip at loads that are below general yielding. At high 

temperatures (i.e., low values of yield stress), strain hardening is needed to raise the local 

tensile stress to the cleavage fracture stress. Ductile fracture results when strain hardening is 

not sufficient to raise the tensile stress to the critical value. The relationship between the 

degree of cleavage fracture and toughness, however, is complex since cleavage cracks can be 

initiated by several mechanisms (e.g., dislocation pile-up, cracking of carbide or nitride particles, 

and cracking of twin intersections). Each mechanism requires a unique stress level. Thus, for 

the same degree of cleavage fracture, the toughness may vary in different CASS materials.

The time-temperature curves for the formation of various phases and the change in the impact 

strength of thermally aged CASS materials,3 indicate that at temperatures above 550°C 

(1022°F), the embrittlement is largely due to formation of the sigma phase, and that below 

500°C (932°F), precipitation of the α' phase leads to embrittlement. Furthermore, the timetemperature transformation curves for Fe-Cr alloys indicate that the α' phase is not stable at 

550°C (1022°F). At 550°C, the Fe-Cr alloys are embrittled after aging for >10 h owing to the 

formation of the sigma phase.4 Consequently, the fracture toughness of embrittled CASS 

materials can be recovered virtually completely by annealing for 1 h at 550°C (1022°F) and 

water quenching. This short heat treatment dissolves the α' phase and prevents formation of 

sigma phase.12 The dissolution of α' has been confirmed by microstructural studies.

5 

 * Per private communications with Mr. M. Guttmann, EdF, Research and Development, Department MMC, 77818 

Moret sur Loing, France, in January 1986.
11

2.2 Distribution and Morphology of Ferrite in CASS Materials

2.2.1 Ferrite Morphology

The degree and kinetics of thermal embrittlement of CASS materials are controlled primarily by 

the amount, size, and distribution of the ferrite phase, and to some extent by the presence of 

carbides or nitrides at the phase boundaries. These material parameters in turn depend on the 

chemical composition of the materials and the manufacturing process. Differences in the 

thermal aging behavior have been observed in CASS materials produced by different foundries, 

suggesting that the material composition and ferrite content are not the only parameters that are 

relevant for thermal aging; manufacturing parameters may also be important.25 

The pseudo binary diagram for Fe-Ni-19%Cr system is shown in Fig. 3. Duplex SSs with high 

Cr contents solidify into a primary δ ferrite phase. Such materials generally have lathy ferrite 

morphology. These materials are most sensitive to thermal aging. Materials that solidify in the 

δ+γ regime exhibit vermicular and interdendritic lacy ferrite morphology. In both cases, during 

cooling of the solidified material, if the concentrations of the γ-forming elements such as C, N, 

Mn, and Ni, are sufficient, a fraction of the δ-ferrite transforms to γ-austenite by solid-state δ to γ

transformation. Furthermore, if the cooling rate between 900 and 600°C (1652–1112°F) is slow, 

δ ferrite can transform to the brittle sigma (σ) phase, and M23C6 carbides can also precipitate at 

the δ/γ phase boundaries, both of which lead to degradation of the mechanical properties of the 

material.25 Therefore, the manufacturing processes require that the casting must be annealed 

at around 1100°C (2012°F) followed by a rapid quench to avoid the formation of these 

deleterious precipitates. 

Figure 3. Pseudo binary diagram for Fe-Ni-19%Cr alloy (Ref. 25).

Typically, the structure of the core of large sand-cast CASS components consists of equiaxed 

grains, and the surface regions contain columnar grains, elongated in the direction of the 

temperature gradient. Steeper temperature gradients result in smaller and more elongated 

columnar grains.25 Examples of equiaxed and columnar grain structures are shown in Figs. 4

and 5, respectively.
12

Cast CF-8 Steel Cast CF-3 Steel

Axial Circum. Axial Circum.

Figure 4. Microstructure along the axial and circumferential sections of centrifugally 

cast CF-8 and CF-3 stainless steel pipes showing equiaxed grain structure.

Figure 5. Microstructure along axial section of a check valve from the 

decommissioned Shippingport reactor showing columnar grains.

The effect of manufacturing process on the thermal embrittlement of CASS materials has been 

investigated by Massoud et al.25 The manufacturing process for castings involves solidification 

of the material from a liquid state at around 1500°C (2732°F), followed by a homogenizing heat 

treatment of the solid at 1050–1150°C (1922–2102°F) and water quenching. The homogenizing 

treatment allows any brittle phases such as σ phase that may have precipitated during 

solidification to dissolve. It also establishes the ferrite-austenite ratio in the material and the 

partitioning of the alloying elements in the two phases. Consequently, the homogenizing 

treatment may be important for thermal embrittlement of the material during reactor service.

The results of the parametric study of the manufacturing process parameters conducted by 

Massoud et al.25 indicate that the microstructural changes in the ferrite by spinodal 

decomposition during thermal aging at temperatures between 250 and 400°C are very sensitive 

to the initial state of the ferrite in the as-quenched condition. Any manufacturing process 
13

parameter that improves the homogeneity of the ferrite solid solution such as long 

homogenizing heat treatments and rapid quench, delay the beginning of the ferrite 

decomposition, which results in a more aging-resistant CASS material. The significant results 

from the EdF study are as follows: 

• The solidification rate affects the morphology of the ferrite-austenite microstucture and 

the characteristics of the toughness transition curve but does not seem to affect the 

aging behavior of the steel. The size and spacing of the ferrite phase increase with a 

decrease in cooling rate. Material with the low cooling rate has a high upper shelf 

Charpy-impact energy. 

• An increase in the homogenizing treatment temperature increases the ferrite content of 

the material and the chemical composition within each phase. Consequently, it affects 

the aging behavior of the steel. The fracture toughness of CASS materials treated at a 

high temperature (which consequently have a high ferrite content) decreases sooner 

than the fracture toughness materials treated at a low temperature. However, the overall 

thermal embrittlement behavior depends on two mechanisms that counter each other. In 

CASS materials with higher ferrite content, the extent of thermal embrittlement is greater 

than it is in materials with low ferrite content. However, the ferrite in high-ferrite 

materials is less sensitive to thermal embrittlement because its Cr content is lower. 

Although the materials treated at low temperatures have low ferrite content and aging 

effects on them start late, they are more sensitive to thermal embrittlement. This 

behavior is discussed further in Section 2.3.

• The homogenizing treatment holding time and the quenching rate affect the beginning of 

the decomposition of the ferrite and consequently the overall kinetics of aging. 

The ferrite morphology of the various CASS materials varies with the ferrite content, chemical 

composition, and size of the casting. Figure 6 shows examples of the ferrite morphology and 

ferrite content in centrifugally cast CF-3 and CF-8 pipes and a static cast CF-3 pump impeller. 

Studies conducted at ANL on 30 heats of CF-3, CF-8, and CF-8M CASS materials showed that 

globular ferrite morphology was observed for materials containing <5% ferrite.12 Some 

differences in morphology were observed for the different grades of CASS materials containing 

>5% ferrite. The CF-8 and CF-8M materials had a lacy morphology while the CF-3 cast 

materials showed a mixture of lacy and acicular ferrite. 

2.2.2 Ferrite Content

Significant variations in ferrite content within a CASS component have been observed in hot-leg 

elbow and crossover-leg elbow removed from the Ringhals reactor.69 The material of the 

elbows is ASTM Specification 351 CF-8M steel, and the ferrite content, determined from the 

modified Schaefler diagram,70 is 20.1 for the hot-leg elbow and 19.8% for the crossover-leg 

elbow. Test rings were cut from the two elbows, and the ferrite content measured with a ferrite 

meter at the inside surface at three different heights of the ring, as well as through the thickness 

of the ring. Around 700 measurements were made, and the results show that the ferrite content 

in the actual components varies significantly. The ferrite content of the hot-leg elbow varies 

from 3.0% to 22.5%, with an average of 13.3% ±4.2% ferrite; that of the crossover-leg elbow 

from 1.5% to 15.0%, with an average of 9.8% ±3.4% ferrite. The results also indicate that for 

both elbows, the measured average ferrite contents are comparable with the values estimated 

from the material chemical composition by using Hull’s equivalent factors71 or the ASTM 

A800/A800M methodology.72,73 
14

Static cast CF-3 Stainless Steel Pump Impeller

Centrifugally cast CF-3 Stainless Steel Pipe

Centrifugally cast CF-8 Stainless Steel Pipe

Figure 6. Ferrite content and morphology of vanes of a static cast CF-3 pump 

impeller and along a circumferential section of regions near the inside 

and outside diameter of centrifugally cast CF-3 and CF-8 pipes.
15

Similar variations in the ferrite content have also been observed in the ANL studies on CASS 

materials, obtained from actual reactor components. The measured ferrite content of vanes of a 

static-cast CF-3 pump impeller and along circumferential section of regions near the inside and 

outside diameter of centrifugally cast CF-3 and CF-8 pipes are higher near the outer surface 

than the inner surface. The values are about 20% higher for the CF-3 pipe (Heat P2) and 40% 

higher for the CF-8 pipe (Heat P1). In addition, the ferrite content of one of the pump impeller 

vane is about 40% higher than that of Vane 1. The ferrite contents estimated from the chemical 

composition by using Hull’s equivalent factors are 17.7, 15.6, and 17.1% for the CF-8 pipe, CF-3 

pipe, and CF-3 pump impeller, respectively. The estimated values are comparable to the 

measured average values of ferrite contents for the CF-3 pipe and pump impeller but lower than 

the measured values for the CF-8 pipe. 

These observations indicate that if measured value of ferrite content is used for design 

calculations or analyses, several locations should be selected across the length and width of the 

component to ensure that it is representative of the entire component. The results also indicate 

that for centrifugally cast SS pipes, the extent of embrittlement is likely to increase from the 

inner surface towards the surface because of the increasing ferrite content. 

The ferrite content in CASS structures depends on the chemical composition and the 

manufacturing process history of the material. Typically, it is (a) measured using metallographic 

examination or instruments that utilize the magnetic response of the casting or (b) estimated 

from the chemical composition of the casting. When the CMTR is available, the ferrite content 

is estimated from the chemical composition of the material, and measuring techniques are used 

when the CMTR is not available.

2.2.2.1 Measured Ferrite 

Until 1973, the ferrite content in duplex structures such as CASS materials was determined by 

metallographic examination of the structure. A sample of the material was polished and etched 

to reveal the ferrite and austenite phases, and a grid was superimposed over the image of an 

optical microscope to determine, by point counting, the percentage of ferrite in the sample. The 

main drawback with this method is that the point-count estimates of ferrite can vary depending 

on the etching technique used to reveal the ferrite phase and on the number of grid points used 

in the measurements. Furthermore, as discussed, the ferrite content in most CASS 

components varies significantly in different regions of the component, and obtaining 

metallographic samples from various regions may not be practical. 

Among the magnetic methods, the Magne-Gage and Feritescope are the most commonly used 

instruments for measuring the ferrite content in CASS materials. The Magne-Gage is a 

continuous-reading type of instrument that uses a spring to measure the attraction between a 

magnet and the material of unknown ferrite content, and the response is compared with that of a 

calibrated sample. Typically, the ferrite number (FN) is measured by using a Magne-Gage in 

accordance with standard American Welding Society (AWS) procedure A4.2-74.74 The 

Feritescope operates on the magneto-induction principle, wherein the relative magnetic 

permeability of the specimen is measured. However, because the magnets or the probes of 

these instruments are small, the surface roughness or curvature of the sample is an important 

parameter that can change the magnetic linkage with the material being measured. In addition, 

phases other than ferrite and austenite may form in the material during service; these may alter 

the magnetic response of the material so that the indicated ferrite content is quite different from

the content of a material with the same chemical composition that has undergone a different 

heat treatment.
16

2.2.2.2 Estimated Ferrite 

Although a quantitative metallographic method gives the most accurate estimate of ferrite 

content, determining the percentage of ferrite from the chemical composition of the material is 

the most common method used to control ferrite during the solidification of the metal from a 

melt. The accuracy of these estimates, however, depends on the accuracy of the chemical 

analysis and on the degree of variability within the casting. In addition, these methods do not 

consider the effects of the casting process. The most commonly used methods for estimating 

ferrite are described below. 

2.2.2.2.1 Hull’s Equivalent Factor:

When a CMTR is available, the ferrite content is calculated from the chemical composition in 

terms of Hull's equivalent factors71 for Ni and Cr, given by

Creq = Cr + 1.21(Mo) + 0.48(Si) – 4.99 (3)

and

Nieq = (Ni) + 0.11(Mn) – 0.0086(Mn)2 + 18.4(N) + 24.5(C) + 2.77, (4)

where the concentrations of the various alloying and interstitial elements are given in wt.%. The 

concentration of N is often not available in a CMTR; if not known, it is assumed to be 0.04 wt.%. 

The ferrite content δc is given by

δc = 100.3(Creq/ Nieq)2 – 170.72(Creq/ Nieq) + 74.22. (5)

The measured ferrite content and values calculated from Hull's equivalent factor for the various 

CASS heats used in studies at ANL,12 GF,1 Electricité de France (EdF),22 National Power 

Figure 7.

Plots of measured ferrite 

content and values for 

various CASS materials 

calculated by using Hull's 

equivalent factor.
17

(NP),21 FRA,7 and the Electric Power Research Institute (EPRI)10 are shown in Fig. 7. For most 

heats, the difference between the estimated and measured values is ±6% ferrite. The results 

also indicate that the calculated ferrite content is generally lower than the measured values for 

CF-8M heats that contained ≥10% Ni. 

2.2.2.2.2 ASTM A800/800M Methodology: 

In this methodology,72 the ferrite content of the casting is estimated from the central line of the 

of the Schoefer diagram73 at the composition ratio of Cr equivalent, Creq, to Ni equivalent, Nieq, 

determined from the formula: 

Creq/Nieq = (Cr + 1.5Si + 1.4Mo + Nb – 4.99)/(Ni +30C + 0.5Mn + 26(N – 0.02) + 2.77) (6)

The values of the composition ratio (Creq/Nieq) for a given ferrite content (F), or vice versa, is 

then determined mathematically from the equation of the central line:

Creq/Nieq = 0.9 + 3.38883 × 10–2F – 5.58175 × 10–4F2 + 4.22861 × 10–6F3 (7)

The measured ferrite content and values calculated from the ASTM A800/A800M methodology 

for the same heats of CASS materials plotted in Fig. 7 are shown in Fig. 8. Since the Nb 

content is typically not reported for CASS CF-3, CF-8, and CF-8M materials, it is assumed to be 

zero and the ferrite content is calculated using Eqs. 6 and 7. Estimated values of ferrite if an Nb 

content of 0.2 wt.% is used would be about 7% higher for CASS materials with 5% ferrite and 

about 4% higher for materials with 30% ferrite. The results indicate that for ferrite contents 

more than 20%, the calculated ferrite content for several heats is lower than the measured 

values. Most of these heats with significantly lower calculated values contained 22.0–23.0 wt.% 

Cr and about 8.0–8.5 wt.% Ni. Ferrite contents estimated from the two methods, Hull's 

equivalent factor and ASTM A800/A800M method show excellent agreement for ferrite contents 

up to 20%. The ASTM A800/A800M method under predicts the ferrite content for CASS 

materials with more than 20% ferrite. Figure 9a shows the difference between the two methods.

Figure 8.

Plots of measured ferrite 

content and values for various 

CASS materials calculated 

using the ASTM A800/A800M 

methodology.
18

2.2.2.2.3 Methodology Developed by EdF: 

The expressions used by EdF to estimate ferrite content in a casting, are slightly different from 

those used in the ASTM A800/800M method. EdF has developed the following expression for 

estimating ferrite,

Ferrite = 21.8R2 – 5.96R + 3.39, (8)

where R is the ratio of Creq and Nieq expressed as,

R = (Cr + Mo + 0.65Si – 17.6)/(Ni +20C + 8.3N + 0.08Mn – 5.18). (9)

A comparison of estimates of ferrite content based on the Hull's equivalent factor and EdF 

method is shown in Fig 9b. In general, the Hull’s method predicts slightly higher ferrite contents. 

The two methods show good agreement for materials with up to 15% ferrite. The ferrite 

contents determined from the EdF method are compared with those from the 

ASTM A800/A800M method in Fig 10. The estimated values based of the EdF and 

A800/A800M methods show good agreement for ferrite contents up to 25%. The A800/A800M 

method under predicts for materials with ferrite content >25%. 

2.3 Kinetics of Thermal Embrittlement

The degree of embrittlement, as documented in the NUREG/CR-4513, Rev. 1, is characterized 

in terms of the Charpy-impact energy of notched toughness specimens. The “best estimates” of 

the degree of embrittlement at reactor operating temperatures are obtained from Arrhenius 

extrapolations of laboratory data obtained at higher temperatures.1 The aging time to reach a 

given degree of embrittlement at different temperatures is determined from: 

, (10)

Figure 9a.

Plots of ferrite content 

calculated by using Hull's 

equivalent factor and those 

estimated from the ASTM 

A800/A800M methodology for 

various CASS materials.
19

Figure 9b. 

Plots of ferrite content for 

various CASS materials 

calculated by using Hull's 

equivalent factors and those 

determined from the EMA 

formula developed by EdF.

Figure 10.

Plots of ferrite content for 

various CASS materials 

estimated by using the ASTM 

A800/A800M methodology and 

those determined from the 

EMA formula developed by 

EdF.

where Q is the activation energy, R is the gas constant, T is the temperature, and P is an aging 

parameter that describes the combined effect of time and temperature on aging. It represents 

the degree of aging reached after 10P h at 400°C (752°F). Thus, P = 1 for aging 10 h at 400°C. 

The aging parameter for any given aging condition is obtained by rewriting Eq. 10 so that,

. (11)
20

The activation energy for the process of embrittlement has been described by Slama et al.7 in 

terms of the chemical composition of the cast material. Thus,

Q(kJ/mole) = –182.6 + 19.9(% Si) + 11.08(% Cr) + 14.4(% Mo). (12)

The activation energy calculated from Eq. 12 for the various CASS materials included in this 

study is in the range of 41–88 kJ/mole (9.8–21.0 kcal/mole) for CF-3 material, 43–91 kJ/mole

(10.3–21.7 kcal/mole) for CF-8, 77–115 kJ/mole (18.4–27.5 kcal/mole) for CF-8M with <10% Ni, 

and 68–128 kJ/mole (16.3–30.6 kcal/mole) for CF-8M with ≥10% Ni. These values are 

generally lower than the values that were obtained from the mechanical property data 

(e.g., Charpy-impact) for most of the CASS materials, particularly for CF-3 and CF-8 materials. 

For example, the activation energies obtained experimentally from the studies at ANL, 

EdF/Framatome, and CEGB are in the range of 86–250 kJ/mole for CF-3, 63–253 kJ/mole for 

CF-8, 81–164 kJ/mole for CF-8M with <10% Ni, and 90–172 kJ/mole for CF-8M with ≥10% Ni. 

However, the calculated values for the CASS CF-3, CF-8, and CF-8M materials investigated in 

the GF study show good agreement with the experimental values of activation energies 

obtained from the Charpy-impact energy data for thermally aged materials. 

Furthermore, the calculated values from Eq. 12 are significantly lower than the activation energy 

of spinodal decomposition in CASS materials. The spinodal decomposition and G-phase 

precipitation in low-temperature-aged CASS materials have been investigated by transmission 

electron microscopy (TEM), atom probe field ion microscopy (APFIM), small angle neutron 

scattering (SANS), and extraction replica techniques.60–67 The activation energy of the spinodal 

reaction in CF-3 SS was 250±30 kJ/mole (60±7 kcal/mole).64 This value is comparable to that 

for Cr diffusion in Fe-Cr alloys. The lower values for the activation energy for thermal 

embrittlement of CASS materials are most likely due to other factors, such as the effect of the 

formation of carbides and nitrides at the phase boundaries or the effect of G-phase and/or γ2

precipitation in ferrite, all of which can change the fracture mechanism of the aged material 

For example, the precipitation of large carbides or nitrides at phase boundaries can initiate 

phase boundary separation by particle cracking. Consequently, a lower degree of spinodal 

decomposition (i.e., smaller amplitude of Cr fluctuation) is needed for a given change in 

mechanical properties. The material would show a reduction in impact strength faster than a 

material without phase boundary carbides would. However, the precipitation of carbides or 

nitrides occurs primarily at 400 or 450°C and is extremely slow at lower temperatures. Thus, 

the influence of phase boundary carbides would tend to increase the apparent activation energy 

of embrittlement measured from mechanical property data.

The other factor that can influence the overall activation energy for embrittlement is the 

precipitation of other second-phase particles in ferrite — in particular, the G phase (a 

multicomponent phase consisting of Ni, Si, Mo, Cr, and Fe and some Mn and C).62,66 The 

kinetics of G-phase precipitation depend on the chemical composition of the cast material.5 For 

some heats, the G phase is observed after times as short as 10,000 h at 400°C, while other 

heats require up to 70,000 h of aging at 400°C for G-phase formation. In general, precipitation 

of the G phase is faster in the Mo-containing CF-8M materials.5,60,62 The aging conditions for 

which the G phase has been detected by TEM or SANS techniques in various CASS materials 

are shown in Fig. 11. The kinetics for the decrease in the Charpy impact energy of the aged 

material are also plotted in the figure. The actual aging times for a given decrease in impactenergy varies significantly for the various heats (shown by the horizontal scatter bars in Fig. 11). 

Generally, the aging times for the CF-8M materials are lower than for the CF-3 or CF-8 

materials. 
21

The mechanism by which the G phase influences thermal embrittlement of CASS materials is not 

well understood. The precipitation of the G phase can influence the kinetics of embrittlement by 

either directly altering the kinetics of spinodal decomposition or by changing the deformation and 

fracture behavior of the ferrite matrix and thereby influencing the effectiveness of spinodal 

decomposition. The only experimental data on the kinetics of spinodal decomposition in CASS 

materials were obtained by modeling the amplitude of Cr fluctuations, measured by APFIM, in 

thermally aged CF-3 steel.18 The results yield an activation energy of 250 kJ/mole. No G phase 

was observed in the steel after 5,000 h at 400 or 350°C. As shown in Fig. 11, most heats require 

≥10,000 h at 400°C and ≥30,000 h at 350°C before G-phase precipitates are detected. 

Figure 11. Arrhenius plots for the formation of the G phase and a reduction in 

impact energy.

The low values of activation energy obtained from mechanical property data (e.g., for the GF CASS 

materials) are most likely due to the effect of G-phase precipitation on the deformation behavior of 

the ferrite matrix. The concomitant precipitation of the G phase may alter the frequency (spacing) of 

Cr fluctuations produced by spinodal decomposition, which would be more effective in strain 

hardening. Thus, a lower degree of spinodal decomposition (i.e., lower amplitude of the Cr 

fluctuations) would be needed for a given change in mechanical properties. The G phase was 

observed in the GF heats of CASS materials, and the measured activation energies for thermal 

embrittlement obtained from the Charpy-impact data were between 63 and 106 kJ/mole.

The above methodology, however, assumes a unique aging behavior at 400°C (752°F), which is 

not observed for CASS materials produced at various foundries by using different manufacturing 

processes. The decrease in RT Charpy-impact energy during thermal aging at 400°C (752°F) 

of several heats of CASS materials1,7,10,12,13–15 is shown in Fig. 12. The results indicate that all 

materials reach “quasi-saturation” RT impact energy (i.e., a minimum value that would be 

achieved by the material after long-term aging, primarily due to spinodal decomposition of the 

ferrite). Although the decrease in the RT impact energy during aging at 400°C occurs primarily 

within 10,000 h, the impact energy for most CASS materials continues to decrease beyond 

10,000 h,1,12–14 but at a much slower rate. Furthermore, thermal aging studies at EdF on 

numerous heats of CF-8M material have shown that the RT Charpy U-notch impact energy for 
22

materials aged for 10,000 h at 350°C is lower than for those aged at 400°C. However, after 

being aged further up to 30,000 h, the impact energy for materials aged at 350°C did not 

change significantly, whereas the impact energy for materials aged at 400°C decreased to a 

lower value than that reached by those aged at 350°C for 30,000 h. 

Note that the proposed methodology for estimating the extent of thermal embrittlement of CASS 

materials is applicable to service times equivalent to 10,000 h at 400°C. This service time 

corresponds to P = 4.0. It represents ≥125 efpy at 290°C for CF-8/CF-3 materials and ≥30 efpy 

at 320°C for CF-8/CF-3 materials and ≥15 efpy for CF-8M materials used within primary 

pressure boundary components. For CF-8/CF-3 materials used in the core support structures 

and core internals, it represents ≥15 efpy at 350°C. The procedure for estimating the thermal 

embrittlement of CASS materials for longer service times will be established when additional 

long-term aging data on RT Charpy-impact energy and fracture toughness J-R curve are 

available for CF-8 and CF-8M materials. Limited data indicate that the concentration of 

(Ni+Si+Mo) in the material is an important parameter for further reduction in fracture properties 

of CASS components.

For a specific CASS material, the actual value of this quasi-saturation RT Charpy-impact energy 

is independent of aging temperature but depends strongly on the chemical composition of the 

material. It is lower for the Mo-bearing CF-8M materials than it is for the Mo-free CF-3 or CF-8 

materials, and it decreases with an increase in the ferrite content and the concentration of C or 

N in the steel. 

Figure 12 also indicates that for a given decrease in the RT Charpy-impact energy, the time for 

aging at 400°C varies by more than two orders of magnitude for the various heats. For 

example, the time required for the impact energy to start decreasing varies from about 50 h 

(EPRI heats) to more than 1000 h (GF heats). The time for the start of thermal aging effects 

varies from 50 to 500 h for the ANL and FRA heats. For some materials, the decrease in impact 

energy is very fast (i.e., low activation energy), and for others, it is slow (i.e., high activation 

energy). Typically, CASS materials that take longer for thermal embrittlement to start have low 

Figure 12. Decrease in Charpy-impact energy for various heats of CASS 

materials aged at 400°C.
23

activation energy, and materials that take short times for embrittlement to start have high 

activation energy. This behavior is consistent with the results of the parametric study of the 

manufacturing process parameters at EdF,25 which showed that CASS materials that are 

solution-treated at a high temperature have a high ferrite content and their thermal 

embrittlement starts early during aging, but they are less susceptible to thermal embrittlement 

(e.g., activation energy for embrittlement is high). On the other hand, CASS materials that are 

solution-treated at a low temperature have low ferrite content and their thermal embrittlement 

starts late during aging, but they are very susceptible to thermal embrittlement (e.g., activation 

energy for embrittlement is low). Such differences may be attributed to compositional 

differences in the material due to differences in the casting process.

The results also indicate that for most CASS materials, the total time to reach saturation impact 

energy is approximately the same for all grades and heats of CASS materials. In other words, 

the time for thermal embrittlement to start plus the time for embrittlement to occur is about the 

same. CASS materials that start early take longer to embrittle, and materials that start late take 

a relatively shorter time to embrittle. Consequently, half the maximum change in RT Charpyimpact energy (i.e., parameter β) and the log of the time to achieve the β reduction in impact 

energy at 400°C (i.e., parameter θ) represent two important parameter for characterizing the 

kinetics of thermal embrittlement.16 The values of parameters β and θ for the various heats of 

CASS materials shown in Fig. 12 are listed in Table 2; parameter α is a shape factor. 

Furthermore, microstructural examination of aged CASS materials suggests that materials that 

take longer for embrittlement to start at 400°C are associated with clusters of Ni-Si, Mo-Si, and 

Ni-Si-Mo in the ferrite matrix.5,60 These clusters are considered precursors of G-phase 

nucleation and precipitation. CASS materials with low activation energy (i.e., fast embrittlement)

show G-phase precipitation after aging, but embrittlement at 400°C takes longer to start. CASS 

materials with high activation energy (i.e., slow embrittlement) do not contain the G phase but 

embrittlement at 400°C takes a relatively short time to start.5,60–62 The presence of Ni-Si-Mo

clusters in the ferrite matrix of an unaged material may be considered a signature of materials 

that are potentially sensitive to thermal embrittlement (i.e., such materials show low activation 

energy for thermal embrittlement but take longer to embrittle at 400°C. 

Since thermally embrittlement of CASS materials is caused primarily by spinodal decomposition

of ferrite,5,11,12 the kinetics of thermal embrittlement are controlled by the amplitude and spacing

of the Cr-rich regions in the ferrite. The low activation energies of thermal embrittlement are 

most likely caused by variations in the spacing of these regions. Atom probe field-ion 

microscopy studies indicate that the spacing between Cr fluctuations decreases with decreasing 

temperature.61,65 Therefore, production heat treatment and the casting process, both of which 

affect ferrite composition and microstructure of the material, would affect microstructural 

evolution during aging as well as the kinetics of embrittlement.

Based on these observations, in NUREG/CR-4513, Rev. 1, the change in RT Charpy-impact 

energy, CV, as a function of time and temperature was expressed in terms of the RT saturation 

impact energy, CVsat, and the kinetics of embrittlement. The decrease in CV with time was 

expressed as 

log10CV = log10CVsat + β{1 – tanh [(P – θ)/α]}, (13)

where the aging parameter P is determined from Eq. 11 The constants α and β are determined 

from the initial RT impact energy, CVint, and CVsat as follows:
24

Table 2. Chemical composition, ferrite content, and kinetics of thermal embrittlement 

for various heats of CASS materials.

Chemical Composition (wt.%) Ferrite (%) CVsat Constants Q

Heat Cr Mo Si Ni Mn C N Calc. Mea (J/cm2) β θ α (kJ/mole)

Argonne National Laboratory

52 19.49 0.35 0.92 9.40 0.57 0.009 0.052 10.3 13.5 161.8 – – – –

51 20.13 0.32 0.86 9.06 0.63 0.010 0.058 14.3 18.0 115.9 0.139 3.53 1.15 204.7

47 19.81 0.59 1.06 10.63 0.60 0.018 0.028 8.4 16.3 163.7 0.069 2.29 1.20 195.7

P2 20.20 0.16 0.94 9.38 0.74 0.019 0.040 12.5 15.6 141.3 0.258 2.83 1.09 218.6

I 20.20 0.45 0.83 8.70 0.47 0.019 0.032 20.4 17.1 134.3 0.094 2.10 1.00 250.0

69 20.18 0.34 1.13 8.59 0.63 0.023 0.028 21.0 23.6 76.7 0.214 3.21 1.07 175.9

P1 20.49 0.04 1.12 8.10 0.59 0.036 0.057 17.6 24.1 53.7 0.305 2.57 0.75 252.7

61 20.65 0.32 1.01 8.86 0.65 0.054 0.080 10.0 13.1 93.3 0.214 3.48 1.20 197.8

59 20.33 0.32 1.08 9.34 0.60 0.062 0.045 8.8 13.5 89.1 0.197 3.14 1.20 249.4

68 20.64 0.31 1.07 8.08 0.64 0.063 0.062 14.9 23.4 47.1 0.301 2.88 0.68 161.1

60 21.05 0.31 0.95 8.34 0.67 0.064 0.058 15.4 21.1 44.8 0.291 2.89 0.88 210.9

56 19.65 0.34 1.05 9.28 0.57 0.066 0.030 7.3 10.1 117.6 – – – –

74 19.11 2.51 0.73 9.03 0.54 0.064 0.048 15.5 18.4 63.1 0.269 3.44 0.70 95.0

75 20.86 2.58 0.67 9.12 0.53 0.065 0.052 24.8 27.8 32.1 0.436 2.82 0.51 139.0

66 19.45 2.39 0.49 9.28 0.60 0.047 0.029 19.6 19.8 87.9 0.208 3.16 1.57 163.9

64 20.76 2.46 0.63 9.40 0.60 0.038 0.038 29.0 28.4 41.1 0.338 2.81 0.60 147.3

65 20.78 2.57 0.48 9.63 0.50 0.049 0.064 20.9 23.4 59.7 0.260 2.99 0.59 153.8

P4 19.64 2.05 1.02 10.00 1.07 0.040 0.151 5.9 10.0 62.7 0.289 2.70 0.62 158.7

63 19.37 2.57 0.58 11.85 0.61 0.055 0.031 6.4 10.4 126.5 0.119 2.83 1.11 155.5

Georg Fischer Co.

284 23.00 0.17 0.52 8.23 0.28 0.025 0.037 43.6 42.0 20.5 0.551 3.66 0.39 85.9

280 21.60 0.25 1.37 8.00 0.50 0.028 0.038 36.3 38.0 19.6 0.609 3.20 0.73 88.9

282 22.50 0.15 0.35 8.53 0.43 0.035 0.040 29.7 38.0 28.5 0.500 3.65 0.39 91.6

281 23.10 0.17 0.45 8.60 0.41 0.036 0.053 31.4 30.0 17.2 0.618 3.76 0.47 89.8

283 22.60 0.23 0.53 7.88 0.48 0.036 0.032 42.6 42.0 18.6 0.599 3.60 0.44 83.7

278 20.20 0.13 1.00 8.27 0.28 0.038 0.030 18.5 15.0 68.3 0.347 3.90 0.29 63.1

279 22.00 0.22 1.36 7.85 0.37 0.040 0.032 39.5 40.0 23.8 0.546 3.06 0.58 93.5

277 20.50 0.06 1.81 8.13 0.54 0.052 0.019 22.5 28.0 30.7 0.466 3.54 0.49 87.7

291 19.60 0.66 1.59 10.60 0.28 0.065 0.054 4.2 6.0 121.9 0.195 3.65 0.35 71.2

292 21.60 0.13 1.57 7.52 0.34 0.090 0.039 23.9 28.0 17.2 0.373 3.07 0.44 98.8

290 20.00 2.40 1.51 8.30 0.41 0.054 0.050 31.3 32.0 15.8 0.624 3.48 0.12 81.0

288 19.60 2.53 1.70 8.40 0.47 0.052 0.022 35.6 28.0 14.9 0.671 2.96 0.66 105.3

287 20.50 2.58 0.51 8.46 0.50 0.047 0.033 37.2 38.0 20.5 0.555 3.46 0.36 90.3

286 20.20 2.44 1.33 9.13 0.40 0.072 0.062 18.9 22.0 15.5 0.594 3.03 0.72 106.4

289 19.70 2.30 1.44 8.25 0.48 0.091 0.032 22.6 30.0 16.2 0.580 3.29 0.41 90.1

285 18.80 2.35 0.86 9.49 0.48 0.047 0.039 14.0 10.0 61.1 0.313 3.60 0.20 89.3

Framatome

A 18.90 0.10 0.99 8.90 1.14 0.021 0.074 6.0 6.3 166.0 0.090 3.44 0.20 111.7

E 21.04 0.08 0.54 8.47 0.80 0.035 0.051 17.6 16.5 45.7 0.334 2.63 0.65 132.9

F 19.72 0.34 1.16 8.33 0.26 0.038 0.026 17.7 12.0 83.2 0.282 2.45 1.23 176.2

C 20.73 0.13 1.09 8.19 0.91 0.042 0.035 20.9 20.1 51.1 0.393 3.30 0.45 83.1

G 20.65 0.02 1.03 8.08 0.74 0.040 0.073 15.3 17.0 62.5 – – – –

H 20.70 0.05 1.18 8.07 0.71 0.050 0.045 18.3 21.5 50.6 – – – –

D 19.15 2.50 0.94 10.32 1.12 0.026 0.063 12.2 13.9 33.0 0.439 3.30 0.40 89.7

I 19.36 2.40 0.98 10.69 0.70 0.020 0.039 14.1 15.5 150.7 – – – –

K 20.80 2.62 0.75 10.45 1.09 0.060 0.056 15.4 14.0 48.5 – – – –

L 20.76 2.48 0.81 10.56 0.79 0.040 0.042 18.6 19.0 30.4 – 3.00 – –

B 20.12 2.52 0.93 10.56 0.83 0.053 0.042 14.0 17.3 28.2 0.478 2.55 0.47 128.6

Westinghouse

C148 20.95 2.63 0.53 9.48 1.02 0.061 0.056 22.1 14.0 53.1 – 2.80 – –

Electric Power Research Institute

EPRI 22.04 0.23 0.84 7.93 0.74 0.030 0.045 36.0 32.0 30.0 0.564 2.10 0.60 225.0
25

α = –0.585 + 0.795log10CVsat (14)

and

β = (log10 CVint – log10CVsat)/2. (15)

The CMTR for a specific CASS component provides information on the chemical composition, 

tensile strength, and possibly the Charpy-impact energy of the material. If CVint is not known, a 

typical value of 200 J/cm2 [or 160 J (118 ft-lb) for a standard Charpy V-notch specimen] may be 

used. The value of θ is not available for CASS components in the field, and can only be 

obtained from aging archival material for 5,000–10,000 h at 400°C (752°F). However, 

parametric studies show that the aging response at reactor temperatures is relatively insensitive 

to the values of θ.75 However, the existing data indicate that θ varies with the material 

composition and ferrite content. Additional data on the kinetics of thermal embrittlement of 

CF-3, CF-3M, CF-8, and CF-8M materials containing a wide range of compositions and ferrite 

contents are needed to establish an expression correlating θ to the material composition. 

Based on the data listed in Table 2, a value of 2.9 for θ (i.e., mean of the experimental data) is 

used to estimate thermal embrittlement at 280–400°C (536–752°F). In the NUREG/CR-4513 

methodology, the activation energy for thermal embrittlement is expressed in terms of both 

chemical composition and the constant θ.16 The activation energy Q (in kJ/mole) for CF-3 and 

CF-8 materials is given by

Q = 10 [74.52 – 7.20 θ – 3.46 Si – 1.78 Cr + 148 N – 61 C], (16)

and for CF-8M materials is given by 

Q = 10 [74.52 – 7.20 θ – 3.46 Si – 1.78 Cr – 4.35 Mn+ 23 N]. (17)

Equations 16 and 17 are slightly different from the expressions proposed by Slama et al. in 

1983 (i.e. Eq. 12).7 These equations are applicable to compositions within ASTM Specification 

A351, with an upper limit of 1.2 wt.% for Mn content. Actual Mn content is used when CASS 

materials contain up to 1.2 wt.% Mn. For materials containing more than 1.2 wt.% Mn, 1.2 wt.% 

is assumed. Furthermore, the values of Q predicted from Eqs. 16 and 17 should be between a 

minimum of 65 kJ/mole (15.5 kcal/mole) and a maximum of 250 kJ/mole (59.8 kcal/mole) 

maximum; Q is assumed to be 65 kJ/mole if the predicted values are lower and 250 kJ/mole if 

the predicted values are higher. However, since several processes are responsible for thermal 

embrittlement of CASS materials, and each process has its own temperature dependence, the 

existing data indicates a change in activation energy of embrittlement with temperature. 

The above expressions for estimating activation energy Q for thermal aging embrittlement of 

CASS materials agree qualitatively with the microstructural and mechanical property data. For 

example, an increase in the value of θ decreases the activation energy, as expected. The 

contributions of Si for all grades of CASS materials and of Mn for CF-8M materials are 

consistent with their effect on the formation of the G phase. These elements should promote 

precipitation of the G phase: hence, the coefficients for these elements should have a negative 

sign, because activation energy for thermal embrittlement is low for materials that show Gphase precipitation. An increase in C or N in the steel will promote carbide or nitride 

precipitation at high temperatures and thus increase the activation energy. The positive sign of 

the constant for the N content agrees with this behavior. The constant for the C content in steel, 

however, has a negative sign. It is likely that C also promotes the precipitation of the G phase, 

a multicomponent phase consisting of Ni, Si, Mo, Cr, and Fe and some Mn and C.62,67
26

2.4 Extent of Thermal Embrittlement

All CASS materials reach the “saturation” RT impact energy (i.e., a minimum value achieved by 

the material primarily because of spinodal decomposition) after long-term aging. The actual 

value of the saturation RT impact energy for a specific CASS material is independent of the 

aging temperature (between 250-450°C) but depends strongly on the chemical composition of 

the steel. It is lower for the Mo-bearing CF-8M materials than for the Mo-free CF-3 or CF-8 

materials, and it decreases with an increase in the ferrite content or the concentration of C or N 

in the steel.16 Typically, the extent of thermal embrittlement has been characterized by the RT 

“normalized” Charpy-impact energy (Charpy-impact energy per unit fracture area).

In the ANL studies,12-17 correlations have been developed for the extent of thermal 

embrittlement at quasi-saturation, CVsat (i.e., the minimum RT Charpy-impact energy that would 

be achieved for the material because of spinodal decomposition), in terms of the chemical 

composition of the material. The extent of thermal embrittlement as a function of the time and 

temperature of the reactor service is estimated from the extent of embrittlement at saturation 

and the correlations describing the kinetics of embrittlement, which are given in terms of the 

material chemical composition and the initial Charpy-impact energy, CVint, of the material in the 

unaged condition. If CVint is not known, a typical value of 200 J/cm2 (118 ft-lb) is assumed. The 

fracture toughness J-R curve for the material is then obtained from the correlation between the 

fracture toughness parameters and the RT Charpy-impact energy used to characterize the 

extent of thermal embrittlement. A common lower-bound J-R curve for various grades of CASS 

materials of unknown chemical composition is defined for a given material specification, ferrite 

content, and temperature. Correlations are also developed for estimating changes in tensile 

strength and Ramberg/Osgood parameters for strain hardening.18 The methodology for 

estimating fracture properties of aged CASS materials has been updated in this report. 

The extent of thermal embrittlement has been extended to operating times equivalent to 

10,000 h at 400°C. The procedure for estimating thermal embrittlement for aging times beyond 

10,000 h at 400°C will be established as and when RT Charpy-impact data are available for CF8 and CF-8M materials aged for 10,000–40,000 h at 400°C. An aging time of 40,000 h at 400°C 

is equivalent to ≥60 efpy at 320°C for CF-8M and ≥120 efpy at 320°C for CF-8/CF-3 materials

used in the primary pressure boundary components, and ≥45 efpy for CF-8/CF-3 materials used 

in reactor core support and core internals. 

2.4.1 Charpy-Impact Energy 

In the ANL studies,12 different correlations are developed to estimate the saturation RT impact 

energy of the various grades of CASS materials. To ensure that the estimates are either 

accurate or conservative for all heats, the saturation RT impact energy for a specific material is 

determined by two slightly different expressions, both correlating the RT Charpy impact energy

with a material parameter, φ, that depends on the material’s ferrite content and its chemical 

composition. The lower value is used to estimate the mechanical properties of thermally aged 

CASS materials. The RT Charpy-impact energies at saturation (i.e., for CASS materials aged 

10,000 h at 400°C), CVsat, observed experimentally at ANL,12-14 GF,1 Westinghouse (WH),2

TWI,6 FRA,7 EPRI10 CEGB,21 EdF,22 and MHI28–32 are plotted as a function of the material 

parameter φ in Fig. 13. The data represents CF-3, CF-3M, CF-8, and CF-8M materials with 3 to 

49% ferrite. The data for grades CF-3 and CF-8 are plotted together, and for grades CF-3M 

and CF-8M, materials containing <10% Ni are plotted separate from those containing ≥10% Ni. 
27

Figure 13. Correlation between RT Charpy-impact energy at saturation and 

the material parameter φ for CASS materials. δc is the calculated 

ferrite content. 
28

A value of 10% Ni is used in this study to determine if primary γ (austenite) forms during 

solidification of the castings from the liquid. For CASS CF-8M compositions containing 

<10% Ni, the solidification sequence is as follows: Liq. → Liq. + δ → δ, with δ → γ in the solid.76 

Austenite nucleates predominantly at ferrite grain boundaries and to a lesser extent at 

interdendritic locations within the ferrite. For CF-8M compositions containing ≥10% Ni, the 

solidification sequence is likely to be as follows: Liq. → Liq. + δ → Liq. + δ + γ → δ + γ, with 

δ → γ continuing in the solid.76 The austenite forms first in the liquid as a secondary phase 

enveloping the primary ferrite. Upon further cooling, it grows in the remaining liquid as well as 

into ferrite. The latter reaction continues below the solidus line. The actual microstructures of 

the casting depend on the Cr/Ni ratio for the specific composition. Because of significant 

differences in the composition and microstructure of the ferrite in CF-8M materials with <10 or 

≥10% Ni, separate expressions have been developed for these two materials. 

The results indicate that for CF-3M and CF-8M materials, the original expressions correlating 

CVsat to the material parameter φ need to be revised to extend their applicability for materials 

containing more than 25% ferrite. The expressions for CF-3 and CF-8 materials do not require 

revision. For these grades, although experimental CVsat for a few heats with high values of φ is 

lower than the predicted value, the chemical composition of these heats was outside the ASTM 

specifications for CF-3 and CF-8 materials. The Cr content in these heats was significantly 

higher than the 21% maximum specified in the specifications, and for some materials, the Ni 

content was also lower than the 8% specified minimum.

For CF-3/CF-8 materials, the expressions in NUREG/CR-4513, Rev. 1, are retained. The bestfit expressions are used to avoid over conservatism in the estimation methodology. The 

saturation value of RT impact energy, CVsat, is the lower value determined from

log10CVsat = 1.15 + 1.36exp(–0.035Φ), (18)

where the material parameter Φ is expressed as

Φ = δc(Cr + Si)(C + 0.4N), (19)

and from

log10CVsat = 5.64 – 0.006δc – 0.185Cr + 0.273Mo – 0.204Si 

+ 0.044Ni – 2.12(C + 0.4N). (20)

For CF-3M/CF-8M materials, the expressions between CVsat and φ have been revised. For 

materials with <10% Ni, the CVsat value is the lower value determined from

log10CVsat = 0.27 + 2.81exp(–0.022Φ), (21)

where the material parameter Φ is expressed as

Φ = δc(Ni + Si + Mn)2(C + 0.4N)/5, (22)

and from 

log10CVsat = 7.28 – 0.011 δc – 0.185Cr – 0.369Mo – 0.451Si 

– 0.007Ni – 4.71(C + 0.4N). (23)
29

For materials with ≥10% Ni, the saturation value of the RT impact energy CVsat is the lower 

value determined from

log10CVsat = 0.84 + 2.54exp(–0.047Φ), (24)

where the material parameter Φ is expressed as

Φ = δc(Ni + Si + Mn)2(C + 0.4N)/5, (25)

and from

log10CVsat = 7.28 – 0.011 δc – 0.185Cr – 0.369Mo – 0.451Si 

– 0.007Ni – 4.71(C + 0.4N). (26)

If not known, the N content is assumed to be 0.04 wt.%. The correlations are optimized using 

mechanical property results on approximately 140 compositions of CASS materials that were 

aged up to 60,000 h at 290–350°C (554–662°F). 

To provide a more realistic comparison, the data obtained for aging temperatures 400°C or 

higher are not used. Figure 14 shows the difference between the estimated CVsat values based 

on the original expressions in NUREG/CR-4513, Rev. 1, and the updated expression, for CF-8M 

and CF-3M materials. The original and updated curves are shown as solid and chain-dash 

lines, respectively. The chemical composition, ferrite content, and saturation RT Charpy-impact 

energy are given in Table 2.

The measured values of CVsat and the lower of the two values estimated from (a) the material 

parameter φ (Eqs. 18, 21, and 24) and (b) the material chemical composition and ferrite content 

δc (Eqs. 20, 23, and 26), are plotted in Fig. 15. The results indicate that the estimates based on 

Eqs. 18–26 are either accurate or conservative. However, the predicted CVsat for four heats 

Figure 14. Comparison of the updated (chain-dash line) and original (solid line) 

correlation between the RT Charpy-impact energy at saturation and 

material parameter φ. 
30

Figure 14. (Contd.)

(two CF-3 and two CF-8M materials) is significantly higher than the measured value. The 

reason for such a large difference is not clear. The expressions given by Eqs. 18–26 for

estimating CVsat for a specific CASS material are correlated to the material's ferrite content and 

its chemical composition because a review of the thermal embrittlement data for aged CASS 

materials indicated that a correlation between the Charpy impact energy and ferrite content 

alone did not yield good results. The CVsat for CF-3, CF-8, and CF-8M materials shown in 

Fig. 13 is plotted as a function of the material ferrite content in Fig. 16; the results show a poor 

correlation. 

Figure 15. Measured values of saturation RT Charpy-impact energy for CF-3, CF-8, 

and CF-8M CASS materials and those estimated from (a) the material 

parameter φ, (b) the material composition and ferrite content, and (c) the 

lower of these two values. 
31

Figure 15. (Contd.)

Figure 16.

Correlation between RT Charpy-impact 

energy at saturation and the ferrite 

content for CF-3, CF-8, and CF-8M 

materials. 
32

2.4.2 Effect of Trace Nb Content 

Limited data indicate a significant reduction in the RT Charpy-impact energy of Heat 4331 of 

CF-8M material aged for only 700 h at 400°C. Unlike most CF-8M materials, which contain only 

trace amounts of Nb (e.g. <0.05 wt.%), Heat 4331 contained 0.2 wt.% Nb. The fracture surface 

of the Charpy-impact test specimen (Fig. 17) show that the phase boundaries are decorated 

with large Nb carbides (or carbo-nitrides) that can crack easily. These phase-boundary 

carbides alter the deformation and fracture behavior of the material, promoting initiation of 

cleavage by particle cracking. None of the other heats of CASS materials included in the ANL

study contained more than trace amounts of Nb. The fracture surfaces of these heats of CASS 

materials exhibit, depending on the extent of embrittlement, a combination of dimpled ductile 

tearing, ductile shear failure, cleavage, and phase-boundary separation. For room-temperature 

tests, the amount of cleavage increased with the extent of embrittlement. 

These differences in the fracture behavior of the Charpy-impact specimens are reflected in the 

ductile-to-brittle transition curves for thermally aged CASS materials. The effect of thermal 

aging on the transition curves for Heats 4331 (23.8% ferrite) and Heat 75 (24.8% ferrite) aged 

for different times at 400°C are shown in Fig. 18. The results show significant differences in the 

transition temperature for the two heats of CF-8M materials. The transition temperature at 

81.25 J/cm2 (i.e., 50 ft-lb) Charpy-impact energy for Heat 75 aged at 400°C for 2,570 h and 

10,000 h is 65°C and 140°C, respectively; for Heat 4331 aged at 400°C for only 700 h, it is 

220°C. Thus, the transition temperature is much higher for Heat 4331, even though it was aged 

for only 700 h. The results also indicate that although the Charpy-impact energy at 270–290°C 

is not significantly different for the three aging conditions, the RT Charpy-impact energy is much 

lower for Heat 4331 than for Heat 75 aged for longer times. For Heat 4331, the Charpy-impact 

energy at 290°C continues to decrease after aging at 400°C for more than 700 h. 

These results indicate the potential effects of a trace amount of Nb content on the thermal 

embrittlement of CASS materials during service in LWRs. The ASTM Specifications A351 and 

A451 for the chemical composition of CF-3, CF-3M, CF-8, and CF-8M grades of CASS do not 

specify any maximum limit for the Nb content in the casting. Typically, the trace Nb content in 

these grades of CASS materials produced in the United States is very low (less than 0.05 wt.%). 

However, castings produced in Europe may contain higher levels of Nb. The source for higher 

Nb content is the use of Type 347 scrap metal to produce the casting. Consequently, the 

amount of Nb is often more than 0.05 wt.% if Type 347 scrap metal is used. 

Figure 17.

Fracture surface of Charpyimpact specimen of Heat 4331 

aged for 700 h at 400°C and 

tested at room temperature 

(Ref. 12). 
33

Figure 18.

Ductile-to-brittle transition 

curves for Charpy-impact 

specimens of thermally aged 

Heats 4331 and 75 of CF-8M 

material (Ref. 12). 

2.4.3 Fracture Toughness J-R Curve 

The fracture toughness J-R curve for a specific CASS material can be estimated from its RT 

Charpy-impact energy. The J-R curve is expressed by the power-law relationship Jd = CΔan, 

where Jd is deformation J per ASTM Specifications E 813-85 and E 1152-87, Δa is a crack 

extension, and C and n are constants. The coefficient C, at RT (25°C) or reactor temperatures

(290–320°C), and the RT Charpy-impact energy for aged and unaged CASS materials are 

plotted in Fig. 19a and b respectively, based on an updated fracture toughness database. 

Fracture toughness data from studies at ANL,12–15 FRA,7,8 EPRI,10 EdF,23,24,26 Mitsubishi Heavy 

Industries (MHI),28–32 The Welding Institute (TWI),6 and Materials Engineering Associates, Inc. 

(MEA),

77 are included in the figure. These plots provide a correlation between coefficient C of 

the Power-law J-R curve and RT Charpy-impact energy of the material. Thus, saturation values 

of C can be obtained form the saturation value of RT Charpy-impact energy. 

Figure 19a. Correlation between RT Charpy-impact energy and coefficient C at RT for 

CF-3, CF-8, CF-3M, and CF-8M CASS materials.
34

At both RT (25°C) and reactor temperatures (290–320°C), the coefficient C decreases with a 

decrease in the RT Charpy-impact energy. Separate correlations are obtained for CF-3 and 

CF-8 materials and for CF-8M materials; the latter show a larger decrease in the fracture 

toughness for a given impact energy. Furthermore, for CF-8M materials, the decrease in the 

values of coefficient C is much greater for RT Charpy-impact energy values that are less than 

about 35 J/cm2 for fracture toughness tests at RT and 41–46 J/cm2 for fracture toughness tests 

at reactor temperatures. However, all of the fracture toughness data for CF-8M materials with 

very low values of RT Charpy-impact energy are for materials containing ≥10% Ni. It is not 

clear whether CF-8M materials with <10% Ni also show a similar behavior. 

As discussed later in this section, data on chemical compositions of CASS piping materials from 

a select sample of nuclear power plants (NPPs) in the United States indicate that at least 9% of 

the CF-8M materials currently used in operating NPPs contain more than 25% ferrite. For these 

materials, the methodology developed earlier in NUREG/CR-4513, Rev. 1, is not applicable for 

flaw tolerance evaluations. In this report, the methodology for estimating thermal embrittlement 

has been extended to cover CASS materials containing more than 25% ferrite. For CF-8M 

materials, a bilinear expression is developed between RT Charpy-impact energy and coefficient 

C of the power-law J-R curve. 

To help ensure that the estimated J-R curve was conservative for all material and aging 

conditions, the correlations for estimating the J-R curves for static-cast materials were obtained 

by subtracting the value of the standard deviation for the fit to the data from the best-fit curve in 

Fig. 19; these curves are shown as chain dot curves. For centrifugally cast materials, the bestfit correlations were used; typically, the data scatter is considerably smaller for centrifugally cast 

materials than static cast materials. For CF-8M materials, the value of the RT Charpy-impact 

energy for the transition from one expression to the other varies between 35 and 46 J/cm2

because of the differences in the standard deviation for the fit to the individual set of data. 

For static-cast CASS materials, the coefficient C of the J-R curve at RT for CF-3 or CF-8 

materials is expressed as

C = 49[CV]0.52; (27)

Figure 19b. Correlation between RT Charpy-impact energy and coefficient C at 290–

320°C for CF-3, CF-8, CF-3M, and CF-8M CASS materials.
35

for CF-8M materials with RT Charpy impact energy values ≥35 J/cm2, it is expressed as 

C = 16[CV]0.67; (28)

and for CF-8M materials with RT Charpy impact energy values <35 J/cm2, it is expressed as 

C = 1.44[CV]1.35. (29)

For static-cast CASS materials, the coefficient C of the J-R curve at 290–320°C for CF-3 or 

CF-8 materials is expressed as

C = 102[CV]0.28; (30)

for CF-8M materials with RT Charpy impact energy values of ≥46 J/cm2, it is expressed as

C = 49[CV]0.41; (31)

and for CF-8m materials with RT Charpy impact energy values <46 J/cm2, it is expressed as

C = 5.5[CV]0.98. (32)

For centrifugally cast CASS materials, the coefficient C of the J-R curve at RT for CF-3 or CF-8 

materials is expressed as

C = 57[CV]0.52; (33)

for CF-8M materials with RT Charpy impact energy values ≥35 J/cm2, it is expressed as 

C = 20[CV]0.67; (34)

and for CF-8M materials with RT Charpy impact energy values of <35 J/cm2, it is expressed as

C = 1.78[CV]1.35. (35)

For centrifugally cast CASS materials, the coefficient C of the J-R curve at 290–320°C for CF-3 

or CF-8 materials is expressed as

C = 134[CV]0.28; (36)

for CF-8M materials with RT Charpy impact energy values ≥41 J/cm2, it is expressed as

C = 57[CV]0.41; (37)

and for CF-8M materials with RT Charpy impact energy values <41 J/cm2, it is expressed as

C = 6.9[CV]0.98. (38)

The distribution of the value of the power-law J-R curve exponent, n, for various grades of 

thermally aged and unaged CASS materials is shown in Fig. 20. The available database 

consists of 129 fracture toughness J-R curve tests at RT and 141 tests at reactor temperatures 
36

of 290–325°C. In general, the exponent n is higher at RT than at reactor temperatures. The 

median value is 0.55 at RT and 0.50 at 290–325°C. The results show that only about 4% of the 

values at reactor temperature and less than 2% of them at RT are below a value of 0.33. 

However, an investigation of the thermal embrittlement of CASS materials at EdF indicated that 

exponent n of the power-law J-R curve can be as low as 0.2 for some heats of CF-8 and CF-8M 

materials, particularly at reactor temperatures.* 

The exponent n of the power-law J-R curve has also been correlated with the RT Charpy-impact 

energy CV. In NUREG/CF-4513, Rev. 1, to ensure that the estimated J-R curves were 

conservative, the correlations between exponent n and the corresponding RT Charpy-impact 

energy for the same material condition represented the lower-bound values of n. The updated 

data for the RT Charpy-impact energy and the corresponding value of fracture toughness J-R 

curve exponent n at RT and 290–325°C, for CF-3, CF-8, and CF-8M CASS materials, are 

plotted in Fig. 21. A review of the updated fracture toughness data indicates that some of the 

recent data are below the correlations in NUREG/CR-4513, Rev. 1,16 between exponent n and 

RT Charpy-impact energy. Consequently, the correlations16 for estimating the J-R curve 

exponent n have been revised; the updated correlations are slightly lower. The revised 

correlations representing the lower-bound values are shown in the Fig. 21. 

For static-cast or centrifugally cast CASS materials, the exponent n at RT for CF-3 materials is

n = 0.16 + 0.13log10[CV]; (39)

 * Per private communications with Dr. Sebastien Saillet, EdF, Research and Development, Department MMC, 77818 

Moret sur Loing, France, in April 2015.

 

(a) (b)

Figure 20. Distribution of the J-R curve exponent for various grades of thermally aged 

and unaged CASS materials at (a) room temperature and (b) 290–325°C.
37

Figure 21. Correlation between the RT Charpy-impact energy and exponent n of the 

power-law J-R curve at RT and 290°C for CF-8M materials. The solid line 

bounds the existing data for exponent n as a function of RT Charpy-impact 

energy.
38

for CF-8 materials, it is 

n = 0.18 + 0.10log10[CV]; (40)

and for CF-8M materials, it is 

n = 0.20 + 0.08log10[CV]. (41)

For static-cast or centrifugally cast CASS materials, the exponent n at 290–320°C for CF-3 

materials is 

n = 0.15 + 0.12log10[CV]; (42)

for CF-8 materials, it is 

n = 0.17 + 0.09 log10[CV]; (43)

and for CF-8M materials, it is 

n = 0.19 + 0.07log10[CV]. (44)

Equations 27–44 may be used to determine the fracture toughness J-R curve of static- or 

centrifugally cast CF-3, CF-8, and CF-8M CASS materials from the RT Charpy-impact energy of 

the material. If the RT Charpy-impact energy is not known, then the saturation fracture 

toughness J-R curves for these CASS materials can be determined from their chemical 

composition available in the CMTRs using Eqs. 18–26 and Eqs. 27–44. The following 

observations can be drawn from this study of thermal embrittlement of CASS materials:49

(a) Among the grades considered, CF-8M materials have the smallest Jd value for a given 

crack extension. The value of Jd at a given crack extension for CF-8M materials is 

generally about half of that of the other grades. 

(b) CF-3, CF-3A, CF-8, and CF-8A materials show a similar extent of thermal aging. The 

value of Jd at a given crack extension for CF-8 and CF-8A materials is generally less 

than 10% lower than that for CF-3 and CF-3A materials.

(c) Static-cast CASS materials are more susceptible to thermal aging than are the 

centrifugally cast materials. The value of Jd at a given crack extension for static-cast 

SS is generally about 20% lower than that for the centrifugally cast material with a 

similar ferrite content. 

(d) Although CF-8M materials show a similar extent of thermal aging on the fracture 

toughness J-R curve both at RT and at the reactor operating temperature, the value of 

Jd at a given crack extension for CF-3, CF-3A, CF-8, and CF-8A materials is generally 

about 20% lower at the reactor temperature than at RT.

These correlations are valid for static-cast and centrifugally cast CF-3, CF-3A, CF-8, CF-8A, 

and CF-8M materials defined by ASTM Specification A351. The criteria used in developing 

these correlations ensure that the estimated mechanical properties are adequately conservative 

for compositions of CASS materials within ASTM A351. The updated correlations are 

applicable to all compositions of CF-8M materials, including materials with ferrite contents 

above 25%. However, in the updated database, there were little or no fracture toughness J-R 

curve data for CF-3 and CF-8 materials with a CVsat of less than 30 J/cm2 (17.7 ft-lb). Therefore, 

the correlations presented in this report may not be applicable to those compositions of CF-3 
39

and CF-8 materials for which the estimated value of CVsat is less than 30 J/cm2 (<17.7 ft-lb). 

Typically, such compositions would contain more than 30% ferrite. Furthermore, the 

correlations may not encompass all metallurgical factors that can arise from differences in 

production heat treatment or casting processes and may be overly conservative. 

Note that these correlations account for the degradation of the mechanical properties of typical 

heats of CASS materials. They do not consider the initial fracture properties of the unaged 

material. Some CASS materials may have low initial fracture toughness, and the estimated J-R 

curves may be higher than the initial value. Therefore, some knowledge about the initial 

fracture toughness of the material is needed to justify the use of the estimated fracture 

toughness. The initial fracture toughness J-R curves may be estimated from the RT Charpyimpact energy of the unaged material. 

Flaw tolerance methods are often used to develop ASME Code Section XI flaw acceptance 

standards or to justify alternatives to the ASME Code Section XI in-service inspection (ISI) 

requirements. Recently, EPRI Report 1019128 (December 2009),78 presented a flaw tolerance 

approach based on elastic-plastic fracture mechanics considerations that could be used in 

combination with a demonstrated inspection method for managing the effects of the aging of 

CASS piping, particularly piping containing more than 20% ferrite content. The sources of the 

CASS data included (a) information obtained from a Westinghouse data search based on a 

random sampling of heats of CASS material from 15 plants (Table 3) and (b) data packages 

Table 3. Primary circuit piping CASS material in Westinghouse plants (Ref. 78).

Plant Name Size (MWe) System 

Loops

Material 

Type

Beaver Valley 2 852 3 CF-8/CF-8A

Callaway 1 1157 4 CF-8/CF-8A

Catawba 1 1153 4 CF-8/CF-8A

Catawba 2 1153 4 CF-8/CF-8A

Comanche Peak 1 1150 4 CF-8/CF-8A

Farley 1 829 3 CF-8/CF-8A

Farley 2 829 3 CF-8/CF-8A

McGuire 1 1180 4 CF-8/CF-8A

McGuire 2 1180 4 CF-8/CF-8A

Millstone 3 1150 4 CF-8/CF-8A

North Anna 1 934 3 CF-8/CF-8A

North Anna 2 788 3 CF-8/CF-8A

South Texas 1 1250 4 CF-8/CF-8A

South Texas 2 1250 4 CF-8/CF-8A

Vogtle 1 1113 4 CF-8/CF-8A

Vogtle 2 1113 4 CF-8/CF-8A

Watts Bar 1 1177 4 CF-8/CF-8A

Watts Bar 2 1177 4 CF-8/CF-8A

Wolf Creek 1158 4 CF-8/CF-8A

Beaver Valley 1 852 3 CF-8M

Cook 1 1090 4 CF-8M

Cook 2 1054 4 CF-8M

Kewaunee 560 2 CF-8M

Prairie Island 2 530 2 CF-8M

Sequoyah 1 1140 4 CF-8M

Sequoyah 2 1140 4 CF-8M
40

from the Sandusky Foundry and Machine Co., NUREG/CR-5024, and Structural Integrity 

Associates. The CASS data were used to estimate the ferrite contents of a representative 

sample of CASS CF-3, CF-8, CF-8A, and CF-8M materials and to perform statistical analyses to 

study the distribution of the ferrite contents of these materials. When information for the Mo and 

N contents was not available, values of 0.5 and 0.04 (wt.%), respectively, were assumed. 

The results yielded mean ferrite content and standard deviation values of 15.9% and 4.9% for 

CF-8 material (total of 333 data points) and 17.6% and 5.4% for CF-8M material (total of 

147 data points). The total amounts of data for CF-3 were too small (fewer than 15 data points) 

to provide meaningful estimates. The distribution of the ferrite content for CF-8M materials 

(Fig. 22) indicated that nearly 9% of the heats of CF-8M material contained more than 25% 

ferrite. Therefore, the updated correlations presented in this report would be applicable to these 

heats of CF-8M material that are currently used in the U.S. PWRs. The expressions presented 

in Eqs. 27–38 are valid for CF-3, CF-8, and CF-8M materials with ferrite contents of up to 40%. 

 

(a) (b)

 

(c) (d)

Figure 22. Distribution of ferrite content in CASS grades of (a) CF-8, (b) CF-8A, (c) CF8M, and (d) CF-3 piping material in Westinghouse PWRs (Ref. 78). 
41

2.4.3.1 Potential Effects of Reactor Coolant Environment

The potential effects of a simulated BWR primary coolant environment on the fracture 

toughness of sensitized Type 304 SS at 98 and 288°C were investigated by Nakajima et al. at 

displacement rates of 0.5, 0.01, and 0.001 mm/min.79 The fracture toughness J-R curve tests at 

98°C were conducted air-saturated water, and the tests at 288°C were conducted in water 

containing 0.2 parts per million (ppm) or 8 ppm dissolved oxygen (DO). Three-point-bend 

specimens were used for the tests at 98°C and 1-T compact tension specimens at 288°C. The 

specimens were sensitized by being heat-treated at 650°C for 0.5, 1, 2, and 4 h; heat treatment 

for 2 h at 650°C was considered the standard sensitized condition. The experimental fracture 

toughness J-R curves at 98 and 288°C for several displacement rates in air and water 

environments are shown in Fig. 23. The results indicate no effect of displacement rate for the 

as-received Type 304 SS. However, for the sensitized material in water environment, the 

fracture toughness J decreased with a decreasing displacement rate and an increasing degree 

of sensitization. At 288°C, the effect of the water environment increased with an increasing DO 

in the environment. The fracture toughness J-R curves obtained at a 0.01 mm/min extension 

rate are representative of a typical fracture toughness J-R curve test. In the ANL studies on 

CASS materials, the J-R curve tests were conducted at an extension rate of about 

0.02 mm/min. 

Figure 23. Fracture toughness J-R curves for sensitized Type 304 SS in simulated 

BWR coolant at 288°C and three different displacement rates (Ref. 79).

Potential effects of reactor coolant environment on fracture toughness have also been studied at 

ANL for neutron-irradiated wrought and cast austenitic SSs.47 The results indicate that the 

effect of the environment may be insignificant for materials with poor fracture toughness 

(e.g., irradiated SSs or thermally aged CASS materials with JIc values below 200 kJ/m2). 

However, a recent scoping study on low-temperature crack propagation (LTCP) for thermally 

aged CASS CF-8 material in PWR environments showed that the fracture toughness J-R curve 

is generally lower in PWR water than in air, and it is significantly lower in PWR shutdown water 

chemistry at 54°C than in air.80 Fracture toughness J-R curve tests were conducted in air on 1-

T CT specimens of CF-8 material (ANL Heat 68) that was thermally aged for about 138,000 h 

(about 15.8 years) at 350°C. The ferrite content calculated from Hull’s equivalent factors was 

15%; it was 23% when measured by a Feritescope. The specimens were either fatigue 

precracked in air at 54°C or were fatigue-plus-SCC precracked in PWR water at 315°C. The 

fracture toughness J-R curve data for these tests are shown in Fig. 24. Note that one of the 

specimens that was precracked in PWR water at 315°C was inadvertently tested at an elevated 
42

temperature of 315°C in PWR primary water chemistry. The updated lower-bound J-R curve at 

RT for CF-8 material with 15–25% ferrite is also shown in the figure for comparison. 

The results indicate that at 54°C, the J-R curve data in air are bounded, with an additional 

margin, by the updated lower-bound J-R curve. However, the J-R curve data for specimens 

precracked in air at 54°C and then tested in PWR shutdown water chemistry at 54°C are 

significantly below the lower-bound curve. The fractography of the test specimens show

multiple fracture planes that are distinct from the primary plane established by the fatigue 

precrack. These results indicate an apparently large effect from the coolant environment on the 

fracture toughness; every material and test condition are identical for the two sets of duplicate 

tests, except one specimen is tested in air and the other in water. The specimens that are 

precracked in PWR water at 315°C and then tested in PWR water at 54°C or 315°C also show

reduced fracture toughness relative to those tested in air, but the difference is less. The J-R 

curve data for the specimen that are cooled down from 315°C and tested at 54°C shutdown 

water chemistry are only marginally below the lower-bound J-R curve, and the data for the 

specimen that are precracked and tested at 315°C PWR primary water chemistry are slightly 

above the lower-bound curve. 

Figure 24. Fracture toughness J-R curve data for thermally aged Heat 68 of 

CF-8M plate at 54°C. The curve represents the lower bound curve at 

RT for static-cast CF-8 material (Ref. 80).

The large reduction in fracture toughness of the aged CASS CF-8 material is attributed to 

potential synergy between hydrogen embrittlement from LTCP and thermal embrittlement 

associated with decomposition of the ferrite at reactor temperatures.80 The authors 

recommended that the multiple fracture paths during J-R curve testing should be examined to 

determine whether any microstructural features are associated with such behavior. 

A similar low-fracture-toughness behavior has also been observed for Alloys 600 and 690 in 

hydrogenated water at 54°C and at low displacement rates (i.e., under quasi-static 

conditions).81,82 For Alloy 600, the JIc value obtained at a displacement rate of 0.05 mm/h is 

30% lower in hydrogenated water at 54–149°C than in air.81 For Alloy 690 tested in 

hydrogenated water at 54°C, the fracture toughness JIc obtained at displacement rates of 0.005 

to 15 mm/h is a factor of 16 lower than that observed at a displacement rate of 305 mm/h.82 

The significant decrease in fracture toughness under a simulated PWR shutdown water 

chemistry has been attributed to hydrogen-induced intergranular cracking. 
43

These results indicate that environment can further decrease the fracture toughness of 

materials relative to the fracture toughness obtained in air. For some heats of wrought and cast 

austenitic SSs and welds, some values of fracture toughness in coolant environments are likely 

to be below the lower-bound trend curve. In particular, the fracture toughness data for 

unirradiated, aged CF-8 material in a PWR SWC environment at 54°C are significantly lower 

because of the potential synergy between the hydrogen embrittlement and thermal 

embrittlement associated with the spinodal decomposition of the ferrite. However, it is not clear 

whether the large reduction in the fracture toughness of thermally aged CASS materials is 

unique and associated with PWR SWC conditions or it can occur under other low-temperature 

LWR environments. Therefore, the minimum acceptable fracture toughness JIc values for 

thermally aged CASS materials in LWR environments at temperatures less than 100°C are 

needed to establish the possible effects of LWR coolant environments on the thermal 

embrittlement of CASS materials. 

2.4.3.2 Potential Effects of High Loading Rate

Typically, the fracture toughness of wrought SSs increases with increases in the loading rate. 

The limited data on the effect of the loading rate on the fracture toughness of CASS materials

are somewhat inconsistent. Fracture toughness tests on a high-ferrite-content CF-3 material in 

the as-cast and aged conditions at three loading rates at RT and 300°C show no significant 

variation for the as-cast material with an increasing strain rate, either at RT or at 300°C.83 

However, for the RT tests on aged material, increasing the loading rate resulted in an increase 

in Jc but a decrease in the slope, dJ/da, of the J-R curve. The slowest loading rate was a quasistatic rate typical of J-integral testing. The second rate was approximately three orders of 

magnitude faster, and the highest rate was about one additional order of magnitude faster. 

Similarly, fracture toughness tests on CF-3M material (16% ferrite) aged for 1000 h at 500°C

and tested at 0°C showed that increasing the loading rate reduced the crack initiation (Jc) as 

well as the slope of the J-R curve to about 18% of the values for quasi-static loading (Fig. 25).84 

Figure 25.

Fracture toughness J-R curves 

for thermally aged CF-3M at 0°C 

and quasi-static and dynamic 

loading rates (Ref. 84).

These limited data that indicate that an inverse loading rate affects the fracture toughness for 

thermally aged CASS materials need to be investigated further to determine the potential 

decrease in fracture toughness at loading rates that are associated with typical seismic activity. 
44

2.5 Methodology for Estimating Thermal Embrittlement of CASS Materials

A flow diagram for estimating mechanical properties of CASS materials during reactor service is 

shown in Fig. 26. The estimation scheme is divided into three sections based on available 

material information. In Section A of the flow diagram, “predicted lower–bound” fracture 

toughness is defined for CF-3, CF-8, and CF-8M materials of unknown composition (i.e., when 

CMTR is not available). For materials with an unknown composition, when the ferrite content of 

the steel is known, a different lower-bound fracture toughness and impact energy are defined for 

materials containing <10%, >10–15%, >15–20%, >25–30%, or >30–40% ferrite. However, as 

discussed earlier in Section 2.2, it is important to make sure that the value of the ferrite content 

used in the estimation scheme is representative of the material. 

Figure 26. Flow diagram for estimating mechanical properties of thermally aged CASS 

materials in LWR systems.
45

Sections B and C of the flow diagram describe the methodology for estimating mechanical 

properties when a CMTR is available (i.e., the chemical composition of the CASS material is 

known). Section B describes the estimation of the “saturation” impact energy and fracture 

toughness J-R curve. The only information needed for these estimates is the chemical 

composition of the material, which is used to estimate the saturation J-R curve for the thermally 

aged material. However, the correlations presented in this report account for the degradation of 

mechanical properties due to thermal aging; they do not explicitly consider the initial fracture 

properties of the unaged material. Some heats of CASS materials may be inherently weak and 

have poor fracture properties in the unaged condition. For such materials, the estimated 

saturation fracture toughness based on the proposed methodology may be higher than the 

fracture toughness of the unaged material. Therefore, it is important to have some information 

about the fracture toughness of the unaged material. The material fracture toughness is 

generally not available in the CMTR. It can be estimated by using the expressions presented in 

Fig. 19 from the initial RT Charpy-impact energy of the unaged material, if known. 

The available fracture toughness J-R curve data at 290–320°C (554–608°F) for unaged CASS 

materials are shown in Fig. 27a and the J-R curves for several heats of wrought Type 304 and 

316 SSs19,77,85–88 are shown in Fig. 27b. The results indicate that the J-R curves for a few 

“weak” heats of static-cast CASS materials are lower than for wrought austenitic SSs. 

Therefore, the saturation fracture toughness properties that should be used for design analyses 

for thermally aged CASS materials depend on whether or not the estimated saturation fracture 

toughness is lower than the initial fracture toughness of the unaged materials. The initial 

fracture toughness of the material can be estimated from its RT Charpy-impact energy. 

However, the fracture toughness of the CASS material is not available in CMTRs. Two different 

options are used to establish the saturation fracture toughness of the thermally aged material. 

In the first option, the initial RT Charpy-impact energy of the unaged material is known, and this 

value is used to estimate the initial fracture toughness of the material. CASS materials with 

poor fracture properties are relatively insensitive to thermal aging, and the fracture toughness of 

the material due to thermal aging during reactor service typically does not change significantly. 

Figure 27. Predicted and measured fracture toughness J-R curves for unaged 

materials (a) CASS at 290–320°C and (b) wrought austenitic SSs at various 

temperatures (Refs. 19,77,85–88). 
46

Therefore, if the estimated saturation fracture toughness of the aged material is higher than the 

fracture toughness of the unaged material, the latter is used as the worst-case toughness for 

that material. 

In the second option, the initial RT Charpy-impact energy is not known; therefore, the minimum 

fracture toughness of all unaged heats and heat treatment conditions for CASS materials is 

used as an upper bound for the estimated fracture toughness. This minimum upper-bound 

fracture toughness of unaged CASS materials is used as the worst-case fracture toughness for 

the material if the estimated saturation fracture-toughness of thermally aged material is higher. 

Typically, the fracture toughness of unaged CASS materials is slightly higher at RT than it is at 

290–320°C. However, for convenience, the minimum fracture toughness of unaged static-cast 

CASS materials at temperatures between RT and 320°C can be expressed as

Jd = 400[∆a]0.40, (45)

and that of centrifugally cast CASS materials can be expressed as

Jd = 550[∆a]0.43. (46)

Based on the recent data from Japan, the lower-bound J-R curve for unaged centrifugally cast 

material has been decreased relative to the original curve in NUREG/CR-4513, Rev. 1. The 

estimation of mechanical properties at any given time and temperature of service (i.e., service 

time properties) is described in Section C of the flow diagram. The initial impact energy of the 

unaged material is required for these estimates. If this is not known, the initial impact energy of 

200 J/cm2 (118 ft-lb) is assumed. However, similar to the procedure in Section B of the flow 

diagram, the initial fracture toughness of the unaged material or the minimum fracture 

toughness of unaged CASS materials is used as an upper bound for the estimates. 

The methodology for estimating fracture toughness of thermally aged CASS materials 

presented in this report can be used to estimate the fracture toughness J-R curves at RT (25°C) 

or reactor temperatures (290–320°C). Fracture toughness J values at temperatures between 25 

and 290°C can be obtained from a linear interpolation of the values at 25 and 290°C (77 and 

608°F). 

The initial tensile properties of the unaged material are needed for estimating the tensile 

strength and Ramberg/Osgood strain hardening parameters. If the initial flow stress of the 

CASS material is known, the JIc value and tearing modulus of the thermally aged material can 

then be determined from the estimated values of the J-R curve and flow stress of the aged 

material. 

However, as mentioned earlier, the above methodology for estimating fracture toughness of 

CASS materials in reactor service is not applicable to CF-8M materials that have more than a 

trace amount of Nb. The chemical requirements for ASTM Specification A351 or A451 do not 

specify any upper limit for Nb. Typically, CF-8M steels contain only trace amounts of Nb. 

However, the Nb content could be high in castings produced by using Type 347 scrap metal. 

For example, in the ANL study, the measured RT Charpy-impact energy of a thermally aged 

heat of CF-8M steel containing about 23% ferrite and 0.2% Nb was significantly lower than that 

predicted from the above methodology. The fracture surface of the Charpy specimen showed 

that the phase boundaries were decorated with large Nb carbide particles that cracked easily. 

Therefore, for CF-8M materials with more than 15% ferrite, it would be advisable to determine 

the Nb content of the material and take appropriate actions if that content is 0.1% or higher.
47

The above methodology only accounts for the thermal embrittlement of CASS materials and is 

therefore applicable to materials outside the reactor core. It does not consider the effects of 

neutron embrittlement or the synergism between thermal and neutron embrittlement. For core 

internal components, which have a prolonged exposure both to elevated temperatures and to 

neutron radiation, the combined effects of thermal and neutron irradiation need to be evaluated. 

An acceptable approach for estimating the fracture toughness of CASS materials used in the 

reactor core is presented in Section 5 of this report.

49

3 ASSESSMENT OF THERMAL EMBRITTLEMENT

3.1 Estimation of Thermal Embrittlement of CASS Materials of Known 

Composition and Service Condition – Service Time Values

The RT Charpy-impact energy of a specific CASS material as a function of service time and 

temperature can be obtained from estimated CVsat (Eqs. 3–5 and 18–26) and the kinetics of 

embrittlement (Eqs. 11,13–17). A value of 2.9 for θ was assumed for all thermal aging 

conditions. The initial Charpy-impact energy, CVint, of the unaged steel is also needed for 

estimating the decrease in impact energy. If this is not known, a typical value of 200 J/cm2

(118 ft-lb) is assumed. The RT Charpy-impact energy observed experimentally and that 

estimated from the chemical composition and initial impact energy of the CASS materials are 

presented in Figs. 19 and 20 of NUREG/CR-4513, Rev. 1. For convenience, these figures in 

NUREG/CR-4513 Rev. 1 are reproduced in Appendix B of this report.

The results indicated that in general, the estimates of RT Charpy-impact energy at aging 

temperatures of ≤330°C (≤626°F) were either accurate or conservative for all grades of CASS 

materials. A few heats showed poor agreement because either the estimated CVsat was higher 

than the experimental value (FRA Heat D and ANL Heat 47) or the estimated activation energy 

was high (FRA Heat C and GF Heat 278). Even at 350°C, because the θ values for most of the 

heats were either greater than or only slightly lower than 2.9, the estimated values of RT 

Charpy-impact energy showed good agreement with the experimental results. The EPRI heat 

and an EdF heat (experimental θ is 2.1 for both heats) alone show nonconservative estimates, 

at 350°C. Therefore, to ensure that the estimates are conservative, a θ value of 2.5 rather than 

2.9 should be used at 330–360°C (626–680°F). 

Once the RT Charpy-impact energy, CV, is known, the service-time coefficient C and 

exponent n of the fracture toughness J-R curve are determined from Eqs. 27–38 and 39–44, 

respectively. The variation in the experimental values of coefficient C as a function of aging 

time and temperature is compared with that estimated from the methodology proposed in this 

report (i.e., material composition and the initial RT Charpy-impact energy) for at least one heat 

each of CF-3, CF-8, and CF-8M material in Figs. 28–31. As discussed earlier for the estimated 

values of RT Charpy-impact energy, the results indicate that at reactor operating temperatures 

(i.e., 280–350°C), the estimated change in the fracture toughness coefficient C with the aging 

time is either accurate or slightly conservative for all grades of CASS material. 

The methodology and expressions for estimating the changes in (a) tensile flow and yield 

stresses and (b) the engineering stress-strain curve of CASS materials, as a function of time 

and temperature of service are described in NUREG/CR-6142.18 The tensile properties of aged 

CASS materials are determined from known material information (i.e., chemical composition 

and initial tensile strength of the steel). The fracture toughness JIc values for the service-aged 

CASS material can be determined from the estimated values of the fracture toughness J-R 

curve and flow stress. 

The proposed methodology can be used to estimate the change in fracture toughness of CASS 

materials for known material composition and service conditions, particularly for service 

temperatures of 280–350°C (536–662°F). Examples of experimental and estimated fracture 

toughness J-R curves for several CF-3, CF-8, and CF-8M materials thermally aged for 30,000 h 

at 350°C or for 50,000 or 53,000 h at 320°C) are shown in Figs. 32–38. Relative to the 

experimental results, the estimated J-R curves are either accurate or slightly conservative. 
50

Figure 28. Estimated and experimental values of coefficient C of the J-R curve 

for static-cast CF-3 plate during thermal aging. Values at 100 h are 

for unaged material.

Figure 29. Estimated and experimental values of coefficient C of the J-R curve 

for static-cast CF-8 plate during thermal aging. Values at 100 h are 

for unaged material.

Figure 30. Estimated and experimental values of coefficient C of the J-R curve 

for static-cast CF-8M plate during thermal aging. Values at 100 h are 

for unaged material. 
51

Figure 31. Estimated and experimental values of coefficient C of the J-R curve for 

centrifugally cast CF-8 pipe during thermal aging. Values at 100 h are for 

unaged material. 

Figure 32. Experimental and estimated fracture toughness J-R curves at RT and 

290°C for an ANL heat of a static cast CF-8 plate. 

Figure 33. Experimental and estimated fracture toughness J-R curves at RT and 290°C 

for an ANL heat of a static cast CF-3 plate. 
52

Figure 34. Experimental and estimated fracture toughness J-R curves at RT and 

290°C for an ANL heat of a centrifugally cast CF-8 pipe. 

Figure 35. Experimental and estimated fracture toughness J-R curves at RT and 

290°C for an ANL heat of a static cast CF-8M plate. 
53

Figure 36. Experimental and estimated fracture toughness J-R curves at RT and 290°C 

for an ANL heat of a static cast CF-8M plate. 

Figure 37. Experimental and estimated fracture toughness J-R curves at RT and 290°C 

for an EdF heats of a static cast CF-8M plate (Ht. DI) and a 50° elbow. 

Figure 38. Experimental and estimated fracture toughness J-R curves at RT and 290°C 

for a MHI heat of a static cast CF-8M pipe. 
54

3.2 Estimation of the Thermal Embrittlement of CASS Materials of Unknown 

Composition: Lower-Bound Values

The ANL methodology provides the expressions for estimating fracture toughness J-R curves of 

unaged and aged CASS materials as a function of the estimated RT Charpy-impact energy; 

which, in turn, is determined from the a material parameter that depends on the chemical 

composition and ferrite content of the material. However, for convenience, lower bound J-R 

curves are defined as a function of ferrite content in the CASS material. These curves bound at 

least 95% of the data. The fracture toughness J-R curve is defined by the power-law 

relationship Jd = CΔan, where Jd is deformation J per ASTM Specifications E 813-85 and E 

1152-87, Δa is a crack extension, and C and n are constants. The coefficient C and exponent n 

for the lower-bound fracture toughness J-R curve are determined from the bounding value of 

CVsat for a range of ferrite contents in the CASS material. 

First the bounding values of the saturation RT Charpy-impact energy, CVsat, for ferrite contents 

<10%, >10–15%, >15–20%, >20–25%, >25–30%, and >30–40% are established for each grade 

of CASS material from the plots of estimated CVsat and ferrite content, as shown in Fig. 39. The

Figure 39. Correlation between saturation RT Charpy-impact energy 

and ferrite content. 
55

RT CVsat for the different grades of CASS materials is the lower value determined from the sets 

of expressions given in Eqs. 18–26. Separate expressions are proposed for CF-8M materials 

containing <10% Ni and those containing ≥10% Ni. The latter are most susceptible to thermal 

embrittlement than the other grades. 

Note that the estimated and not measured value of RT Charpy-impact energy is used in this 

methodology because a value that is representative of a casting would require tests on several 

specimens taken from different portions of the casting. This may not be always possible. The 

estimated CVsat and the corresponding values of coefficient C and exponent n of the J-R curve 

at RT and 290–320°C (550–608°F) for CF-3, CF-8, and CF-8M with <10 and ≥10% Ni and

various ranges of ferrite content are listed in Table 4. The estimated lower-bound J-R curves at 

RT and at 290–320°C for some of the ferrite ranges, are shown in Figs. 40 and 41, respectively, 

for static-cast materials, and in Figs. 42 and 43, respectively, for centrifugally cast material. 

These plots are updated versions of Figs. 3 and 4 of NUREG/CR-4513, Rev. 1.16 The lowerbound fracture toughness J-R curves can be used for completely embrittled CASS materials of 

unknown composition. 

Figure 39. (Contd.)
56

Table 4. The lower-bound J-R curve at RT and 290–320°C for aged CASS materials. 

Estimated Static Cast Material Centrifugally Cast Material

Material CVsat Room Temp. 290–320°C Room Temp. 290–320°C 

Grade (J/cm2) C n C n C n C n

Ferrite Content >30–40%

CF-3/CF-3A 27 270 0.35 256 0.32 314 0.35 336 0.32

CF-8/CF-8A 22 242 0.31 241 0.29 282 0.31 317 0.29

CF-8M (Ni <10%) 14 49 0.29 71 0.27 60 0.29 89 0.27

CF-8M (Ni ≥10%) 9 27 0.27 46 0.26 33 0.27 57 0.26

Ferrite Content >25–30%

CF-3/CF-3A 31 292 0.35 267 0.33 340 0.35 351 0.33

CF-8/CF-8A 24 259 0.32 250 0.30 301 0.32 328 0.30

CF-8M (Ni <10%) 17 65 0.30 87 0.28 80 0.30 109 0.28

CF-8M (Ni ≥10%) 11 35 0.28 55 0.26 43 0.28 69 0.26

Ferrite Content >20–25%

CF-3/CF-3A 37 321 0.36 281 0.34 373 0.36 369 0.34

CF-8/CF-8A 28 279 0.33 260 0.30 325 0.33 342 0.30

CF-8M (Ni <10%) 21 90 0.31 111 0.28 111 0.31 139 0.28

CF-8M (Ni ≥10%) 13 47 0.29 70 0.27 59 0.29 87 0.27

Ferrite Content >15–20%

CF-3/CF-3A 46 360 0.38 298 0.35 418 0.38 392 0.35

CF-8/CF-8A 34 307 0.33 274 0.31 357 0.33 360 0.31

CF-8M (Ni <10%) 29 135 0.32 149 0.29 167 0.32 187 0.29

CF-8M (Ni ≥10%) 18 70 0.30 92 0.28 86 0.30 115 0.28

Ferrite Content >10–15%

CF-3/CF-3A 61 416 0.39 323 0.36 484 0.39 424 0.36

CF-8/CF-8A 43 346 0.34 292 0.32 403 0.34 384 0.32

CF-8M (Ni <10%) 43 198 0.33 228 0.30 247 0.33 266 0.30

CF-8M (Ni ≥10%) 26 115 0.31 132 0.29 142 0.31 166 0.29

Ferrite Content <10%

CF-3/CF-3A 91 512 0.41 361 0.39 595 0.41 474 0.39

CF-8/CF-8A 60 411 0.36 320 0.33 478 0.36 421 0.33

CF-8M (Ni <10%) 74 285 0.35 286 0.32 357 0.35 332 0.32

CF-8M (Ni ≥10%) 43 199 0.33 229 0.30 249 0.33 267 0.30

3.3 Screening Criteria for Susceptibility of CASS Materials to Thermal 

Embrittlement

An EPRI report on the thermal aging embrittlement of CASS components proposed using the 

J value at a crack extension of 2.5 mm (0.1 in.), J2.5, to differentiate between nonsignificant and 

potentially significant reductions in the fracture toughness of thermally aged CASS materials.50 

Flaw tolerance evaluations were presented in Appendices A and B of the EPRI report to support 

the choice of a threshold value of J2.5 = 255 kJ/m2 (1456 in.-lb/in.2). The NRC staff found that 

the use of J2.5 = 255 kJ/m2 as a screening approach for the fracture toughness of CASS 

materials is acceptable.51 The screening criteria to determine the susceptibility of CASS 

components to thermal aging embrittlement are outlined in Table 1.51 

The expressions presented in Fig. 39 and the methodology described in Section 2.4.3 for 

estimating the corresponding fracture toughness J-R curve for the RT Charpy-impact energy 

trend curves in Fig. 39 can be used to check the validity of the ferrite content criteria given in 
57

Figure 40. Estimated lower-bound J-R curves at RT for static-cast CASS 

materials with ferrite contents of >25–30%, >20–25%, and 

>15–20%. 
58

Figure 41. Estimated lower-bound J-R curves at 290–320°C for static-cast 

CASS materials with ferrite contents of >25–30%, >20–25%, and 

>15–20%. 
59

Figure 42. Estimated lower-bound J-R curves at RT for centrifugally cast 

CASS materials with ferrite contents of >25–30%, >20–25%, and 

>15–20%.
60

Figure 43. Estimated lower-bound J-R curves at 290–320°C for centrifugally 

cast CASS materials with ferrite contents of >25–30%, >20–25%, and 

>15–20%. 
61

Table 1. The saturation J2.5 corresponding to the RT Charpy-impact energy trend curves in 

Fig. 39 are shown in Figs. 44 and 45 for static-cast and centrifugally cast materials, respectively. 

In these figures, the updated screening criterion is represented by the ferrite content when the 

J2.5 value decreases below the acceptable threshold value of 255 kJ/m2. 

The results indicate that for CF-3 and CF-8 materials, values of J2.5 for both static-cast and 

centrifugally cast materials are significantly above the threshold value of 255 kJ/m2. Therefore, 

the screening criterion that states that the reduction in fracture toughness due to thermal 

embrittlement of centrifugally cast CF-3 and CF-8 materials is "nonsignificant" is valid, and the 

criterion that the reduction in the fracture toughness of static-cast CF-3 and CF-8 materials is 

"significant" only for materials with more than 20% ferrite is a conservative criterion. 

Figure 44. Saturation J at a 2.5 mm crack extension as a function of the ferrite 

content for static-cast CF-3, CF-8, and CF-8M CASS materials. 
62

Figure 45. Saturation J at a 2.5 mm crack extension as a function of the ferrite 

content for centrifugally cast CF-3, CF-8, and CF-8M CASS materials. 

The results for CF-8M steels with <10% Ni indicate that the J2.5 values are above the 255 kJ/m2

threshold value for static-cast materials with ferrite contents of <16% and for centrifugally cast 

materials with ferrite contents of <19%. Therefore, the existing criterion that the reduction in the 

fracture toughness of static-cast CF-8M materials containing <10% Ni is "significant" only for 

materials with more than 14% ferrite is also a conservative criterion. However, for centrifugally 

cast CF-8M materials containing <10% Ni, the threshold ferrite content above which the 

reduction in the fracture toughness of the material is considered "significant" should be 

decreased from 20% ferrite to 19% ferrite. 

Similarly for CF-8M steels with ≥10% Ni, the J2.5 values are above the 255 kJ/m2 threshold 

value for ferrite contents of <11% for static-cast materials and <13% for centrifugally cast 
63

materials. Therefore, for CF-8M materials containing ≥10% Ni, the threshold ferrite content 

above which the reduction in the fracture toughness is considered "significant" should be 

decreased from 14% ferrite to 11% ferrite for static-cast materials and from 20% ferrite to 13% 

ferrite for centrifugally cast materials. The revised screening criteria for the thermal-aging 

susceptibility of CASS CF-3, CF-3M, CF-8, and CF-8M materials are given in Table 5. The 

screening criteria for the thermal-aging susceptibility of CASS materials that have been changed 

are as follows.

(i) The criterion for static-cast and centrifugally cast CF-8M materials with ≥10% Ni.

(ii) The criterion for centrifugally cast CF-8M materials with <10% Ni.

Table 5. Updated screening criteria for thermal-aging susceptibility of CASS CF-3, CF-8, 

and CF-8M materials.

Mo Content (wt.%) Casting Method Ferrite Content (%) Susceptibility Determination

High (2.0–3.0) Static ≤14 (≤11) Not susceptible

with <10% Ni (≥10% Ni) >14 (>11) Potentially susceptible

Centrifugal ≤19 (≤13) Not susceptible

>19 (>13) Potentially susceptible

Low (0.5 max.) Static ≤20 Not susceptible

>20 Potentially susceptible

Centrifugal All Not susceptible

3.4 Estimation of Tensile Flow Stress 

This section is essentially the same as Section 3.4 of NUREG/CR-4513 Rev. 1. The tensile flow 

stress of aged CASS materials can be estimated from correlations between the ratio of the 

tensile flow stress of aged and unaged materials and a normalized aging parameter. Based on 

the analysis described in NUREG/CR-6142, the ratio of the tensile flow stress (Rf) of aged and 

unaged CASS materials (σfaged/σfunaged) is plotted as a function of a normalized aging parameter 

(P – θ + 2.9) in Fig. 46. Flow stress is defined as the mean of the 0.2% yield strength and 

ultimate strength, and the aging parameter is normalized with respect to a θ value of 2.9. In 

NUREG/CR-4513, Rev. 1, the aging parameter P was determined from Eq. 11 and experimental 

values of activation energy. The correlations between Rf and the normalized aging parameter 

used for estimating flow stress were obtained by subtracting the value of the standard deviation 

for the fit to the data from the best-fit curve. At both RT and 290°C, the Rf increases with 

thermal aging; the increase in the flow stress of CF–3 steels is the smallest and the increase in 

the flow stress of CF–8M steels is the largest. 

The tensile flow stress of aged CASS materials can be estimated from the initial tensile flow 

stress and the correlations given in Fig. 46. Note that the x-axis in these plots is reduced to P 

for a θ value of 2.9. At RT, the tensile-flow-strength ratio, Rf = (σfaged/σfunaged) for CF-3 steel is 

given by

Rf = 0.90 + 0.05P (1.00 ≤ Rf ≤1.10); (47)

for CF-8 steel, it is given by

Rf = 0.84 + 0.08P (1.00 ≤ Rf ≤1.16); (48)
64

Figure 46. Flow stress ratio Rf of aged CF-3, CF-8, and CF-8M materials at RT and 290°C 

as a function of the normalized aging parameter. The solid lines represent 

correlations obtained by subtracting σ from the best-fit curve. 
65

and for CF-8M steel, it is given by

Rf = 0.77 + 0.10P (1.00 ≤ Rf ≤1.19). (49)

At 290°C (554°F), the Rf for CF–3 steel is given by

Rf = 0.87 + 0.06P (1.00 ≤ Rf ≤1.08); (50)

and for CF-8 steel, it is given by

Rf = 0.83 + 0.09P (1.00 ≤ Rf ≤1.14); (51)

and for CF-8M steel, it is given by

Rf = 0.69 + 0.14P (1.00 ≤ Rf ≤1.24). (52)

The minimum and maximum values of the ratio Rf are given for each grade of steel and each 

temperature; a minimum or a maximum value is assumed, respectively, when the calculated 

ratio is smaller than the minimum ratio or greater than the maximum ratio.

Equations 50-52 are valid for service temperatures between 280 and 330°C (536 and 626°F) 

and ferrite contents of >7% for CF-8M steel and >10% for CF-3 and CF-8 steels. Thermal aging 

has little or no effect on the tensile strength of CASS materials with low ferrite content. The 

available database is inadequate for estimating the tensile properties at service temperatures of 

<280°C (<536°F). The estimated values of tensile flow stress at 290°C (554°F) and at RT for 

various heats of aged CASS materials are obtained by first determining the aging parameter 

from Eq. 11, and activation energy form Eqs. 14–17 (using a θ value of 2.9). The tensile flow 

stress is then estimated from Eqs. 47–52 and the initial flow stress of the material. The fracture 

toughness JIc values for aged CASS materials is then determined from the estimated J-R curve 

and flow stress. Only the chemical composition, the initial Charpy-impact energy, and the flow 

stress of the unaged material are used for the estimates. The estimated JIc values show good 

agreement with the experimental results; in most cases, the estimated JIc is lower but within 

30% of the observed value.16 

The data on the tensile properties of CASS materials indicate that the increase in yield strength 

due to thermal aging is much lower than the increase in ultimate strength. At RT, the tensileyield-strength ratio Ry = (σyaged/σyunaged) for CF-3 steel is given by

Ry = 0.873 + 0.048P (1.00 ≤ Ry ≤1.07); (53)

for CF-8 steel, it is given by

Ry = 0.798 + 0.076P (1.00 ≤ Ry ≤1.10); (54)

and for CF-8M steel, it is given by

Ry = 0.708 + 0.092P (1.00 ≤ Ry ≤1.10). (55)

At 290°C (554°F), the tensile-yield-strength ratio Ry = (σfaged/σfunaged) for CF-3 steel is given by

Ry = 0.844 + 0.058P (1.00 ≤ Ry ≤1.05); (56)

for CF-8 steel, it is given by
66

Ry = 0.788 + 0.086P (1.00 ≤ Ry ≤1.09); (57)

and for CF-8M steel, it is given by

Ry = 0.635 + 0.129P (1.00 ≤ Ry ≤1.14). (58)

The minimum and maximum values of the tensile-yield-strength ratio Ry are given for each 

grade of steel and temperature. Equations 56–58 are valid for service temperatures between 

280 and 330°C (536 and 626°F) and ferrite contents of >7% for CF-8M steel and >10% for CF-3 

and CF-8 materials. Similar to the flow stress estimations, the aging parameter and activation 

energy are obtained from Eqs. 11 and 14–17 and by using θ value of 2.9. Tensile yield strength 

is then estimated from Eqs. 56–58 and the initial yield strength of the material. The results 

indicate that the estimated values are conservative for most material and aging conditions.

The engineering stress versus strain behavior of aged CASS materials can also be obtained 

from the estimated flow stress.18 The engineering stress-versus-strain curve is expressed by 

the Ramberg-Osgood equation

, (59)

where σ and ε are engineering stress and strain, respectively; σ0 is an arbitrary reference

stress, often assumed to be equal to the flow or yield stress; the reference strain ε0 = σ0/E; α1

and n1 are Ramberg-Osgood parameters; and E is the elastic modulus. The Ramberg-Osgood 

equation can be rearranged to the form

, (60)

which is more convenient for fitting stress-versus-strain data; α1 can be determined at σ/σf = 1 

and n1 can be obtained from the slope of the log-log plot of Eq. 60. The parameter n1 is 

different for the three grades of CASS materials but does not depend on the aging condition. 

The parameter α1 decreases with aging and shows good correlation with the flow stress σf. For 

engineering stress-versus-strain curves up to 5% strain, the Ramberg-Osgood parameters at 

RT for CF-3 materials are given by

α1 = 143.9 – 0.267σf (n1 = 6.1); (61)

for CF-8 steel, it is given by

α1 = 157.9 – 0.300σf (n1 = 6.4); (62)

and for CF-8M steel, it is given by

α1 = 50.9 – 0.0724σf (n1 = 5.6). (63)

At 290°C (554°F), the Ramberg-Osgood parameters for engineering stress-vs.-strain curves up 

to 5% strain, for CF-3 materials, are given by
67

α1 = 102.1 – 0.235σf (n1 = 6.2); (64)

for CF-8 steel, it is given by

α1 = 153.3 – 0.373σf (n1 = 7.1); (65)

and for CF-8M steel, it is given by

α1 = 145.9 – 0.314σf (n1 = 6.6). (66)

Similar correlations have also been developed for stress-versus-strain curves up to 15% strain 

or up to the ultimate strength.18 

69

4 USE OF METHODOLOGY IN ASME CODE, SECTION XI

This section is an addition to the report; it covers a topic that was not included in NUREG/CR4513 Rev. 1. The estimated lower-bound fracture toughness J-R curves described in 

NUREG/CR-4513, Rev. 1 for thermally aged CASS materials were compared with the fracture 

toughness J-R curve used in the 1989 edition of the ASME Section XI, Subsection IWB-3640

“Evaluation Procedures and Acceptance Criteria for Austenitic Piping,” for evaluation of flux 

welds.49 The comparison is shown in Fig. 47 for static-cast and centrifugally cast CASS 

materials. The results show that the lower-bound fracture toughness of thermally aged CASS 

material with up to 25% ferrite is similar to the fracture toughness J-R curve used in Subsection 

XI IWB-3640 to evaluate SAWs. The procedures in ASME Section XI Subsection IWB-3640 

reduce the load bearing capacity of the SS component to account for the reduced fracture 

toughness of the SAWs, based on elastic-plastic fracture mechanics analyses.89,90 Because 

the lower-bound fracture toughness of thermally aged CASS steel is similar to the fracture 

toughness of SAWs used in the elastic-plastic fracture mechanics analyses of the 1989 edition 

of ASME Section XI IWB-3640, the procedures in IWB-3640 for SAWs are directly applicable to 

CASS materials. 

Figure 47. Comparison of the lower-bound J-R curve at 290°C for aged static-cast 

CF-8M material estimated by using the NUREG/CR-4513, Rev. 1, 

expressions, with the SAW data used to develop ASME Section XI, 

Subsection IWB-3640 evaluations. 

Furthermore, since the flaw evaluation is based on the unaged material ultimate strength, this 

approach would be conservative. Experimental data indicate that the flow stress (i.e., half of the 

sum of the ultimate and yield strengths) is increased by about 10%, 14%, and 24% for CF-3 and 

CF-3A, CF-8 and CF-8A, and CF-8M materials, respectively.16 A higher ultimate stress would 

increase the load-bearing capability of a component. Therefore, the procedures developed in

Subsection IWB-3640 for SAWs have been accepted for evaluating flaws in thermally aged 

CASS materials to address aging degradation concerns associated with license renewal

applications.

49 The use of the IWB-3640 SAW procedures for evaluating flaws in thermally aged 

CASS components is considered conservative because, (a) the lower-bound fracture toughness 

of thermally aged CASS is similar to the fracture toughness used in IWB-3640 to evaluate SAW, 

(b) the actual fracture toughness of a thermally aged CASS component in a U.S. NPP would 

likely be higher than the ANL lower-bound fracture toughness, and (c) the thermally aged 
70

components would be able to withstand more loads because of the increased ultimate strength

resulting from thermal aging. 

The ASME Section XI Subsection IWB-3641 “Evaluation Procedures Based on Flaw Size” 

states; Evaluation procedures based on flaw size may be used subject to the following: 

(a) The evaluation procedures and acceptance criteria are applicable to austenitic pipe NPS 4 

or greater and portions of the adjoining pipe fittings within a distance of √rt of the weld 

centerline (where r is the nominal outside radius and t is the nominal thickness of the pipe). 

(b) The evaluation procedures and acceptance criteria are applicable to pipe and pipe fittings 

(and associated weld materials) which: 

1. are made of wrought stainless steel, Ni-Cr-Fe alloy, or cast stainless steel (with ferrite 

level less than 20% or 20FN; 

2. have a specified minimum yield strength less than 45 ksi; and 

3. have Sm values given in Table I-1.2 of Section III. 

(c) For cast stainless steel materials, adequate toughness for the pipe to reach limit load after 

aging shall be demonstrated. 

The methodology and evaluation procedures are described in Subsections IWB-3641.1 and 

IWB-3641.2, respectively. A flaw growth analysis is performed on the detected flaw to 

determine the maximum growth during a specified evaluation period. The flaw evaluation is 

based on the analytical procedures described in Section XI Nonmandatory Appendix C to 

determine the critical flaw parameters. The maximum allowable flaw depth of a circumferential 

flaw under normal operating conditions is calculated from Table IWB-3641-1 for flaws in base 

metal and gas metal-arc weld (GMAW) and gas tungsten-arc weld (GTAW), and from 

Table IWB-3641-5 for flaws in SAW and shielded metal arc weld (SMAW). Similarly, the 

maximum allowable flaw depth of a circumferential flaw under emergency and faulted conditions 

is calculated from Table IWB-3641-2 and IWB-3641-6, respectively for base metal and 

GTAW/GMAW, and SAW/SMAW. 

Thus, the use of the ASME Section XI, Subsection IWB-3640 (the 1989 edition), SAW 

procedures for evaluating flaws in thermally aged CASS components is considered to be a 

“screening” step to determine whether a further, detailed flaw evaluation that accounts for actual 

plant-specific material properties should be performed. The procedures in IWB-3640 for SAWs 

have been available since the winter 1985 Addenda for Section XI, and they have been applied 

successfully by utilities without resulting in unnecessary component repairs or replacements. 

However, note that the ANL methodology of NUREG/CR-4513, Rev. 1, is not applicable to 

CASS CF-8M materials containing ˃25% ferrite or to CF-8M materials containing more than 

trace amounts of Nb. Even then, the proposed flaw evaluation procedures, which are based on 

the lower-bound fracture toughness of thermally aged CASS materials, are expected to be 

sufficient in the vast majority of cases. 

In this report, the plots in Fig. 47 have been updated to include a comparison of the new lowerbound fracture toughness J-R curve presented in Figs. 40 and 42 with the J-R curve of SAWs 

used to develop the ASME Section XI, Subsection IWB-3640 evaluations. The results for staticcast and centrifugally cast CF-8M materials containing <10% Ni or ≥10% Ni, are shown in 

Figs. 48 and 49, respectively. These plots indicate that the use of the procedures in IWB-3640 

for SAWs for evaluating flaws in aged CASS materials may not be adequate for CF-8M 

materials with ≥10% Ni and containing >10% ferrite, particularly for static cast material. 
71

Similarly, the IWB-3640 procedure for SAWs may not be adequate for CF-8M materials with 

<10% Ni and containing >15% ferrite static cast material and 20% ferrite for centrifugally cast 

materials. The lower-bound J-R curves listed in Table 4 and shown in Figs. 40–43 should be 

used for these materials. 

Figure 48. Comparison of the lower-bound J-R curve at 290°C for aged static-cast 

CF-8M material estimated by using the updated expressions, with the 

fracture toughness of SAW data used to develop ASME Section XI, 

Subsection IWB-3640 evaluations. 

Figure 49. Comparison of the lower-bound J-R curve at 290°C for aged centrifugally 

cast CF-8M estimated by using the updated expressions, with the fracture 

toughness of SAW data used to develop ASME Section XI, Subsection 

IWB-3640 evaluations. 

4.1 Current Editions of the ASME Code Section XI 

As discussed above, the procedures developed in the 1989 edition of the ASME Code 

Subsection IWB-3640 for SAWs have been accepted for evaluating flaws in thermally aged 

CASS materials to address aging degradation concerns associated with license renewal 
72

applications.49 Although the revised lower-bound fracture toughness J-R curves shown in 

Figs. 48 and 49 indicate that the Subsection IWB-3640 flaw evaluation methodology may not be 

applicable to some heats of CF-8M materials, particularly those containing ≥10% Ni, the IWB3640 procedures are applicable for CF-3, CF-8, and some heats of CF-8M materials. However, 

in 1996, Tables IWB-3641-5 and 6 were deleted, Subsection IWB-3641.2 “Evaluation” item 

(c) was revised, and the maximum allowable flaw depth are now calculated using Tables IWB3641-1 and 2 for normal operating conditions and emergency and faulted conditions 

respectively. In addition, Tables IWB-3641-1 and 2 were revised to include Z factors load 

multipliers that are used to modify stress ratio for performing flaw evaluations of austenitic welds 

fabricated by SMAW and SAW. The revised flaw evaluation methodology is applicable to cast 

stainless steels, with a minimum yield strength not greater than 310 MPa (45 ksi). However, the 

methodology does not address thermal aging effects for CASS materials. 

Thus, in 1995 and later versions of the ASME Section XI Subsection IWB-3640 evaluation 

procedures and acceptance criteria for austenitic piping, determination of the allowable flaw 

depth based on Tables IWB-3641-5 and 6 has been replaced by the Z factor load multiplier 

approach to modify the stress ratio for SMAW and SAW flaw evaluations. However, the 

applicability of the SMAW/SAW flaw evaluations using the Z factor load multiplier approach to 

flaw evaluations of thermally aged CASS materials needs to be examined. 
73

5 COMBINED EFFECTS OF THERMAL AND 

NEUTRON EMBRITTLEMENT

This section is an addition to the report; it covers topics that were not included in NUREG/CR4513 Rev. 1. Reactor core internal components are subjected to prolonged periods of both 

elevated temperatures and neutron irradiation. The thermal aging and neutron irradiation 

embrittlement of CASS6–18 and wrought austenitic SSs36–47 have been investigated individually, 

but the possibility of a combined interaction between the thermal and neutron embrittlement of 

materials with a duplex structure is an issue associated with reactor core internal components 

that has been of concern. Recent data indicate that concurrent exposure to elevated 

temperatures and high neutron fluence levels could result in a combined effect, in which the

service-degraded fracture toughness would be reduced from the levels predicted independently 

for either of the two mechanisms.91,92 Furthermore, for SSs with a duplex structure, neutron 

embrittlement of the ferrite phase occurs much faster than it does for the austenitic phase. The 

irradiation temperature is an important factor in establishing the extent of embrittlement of the 

ferrite.

As discussed earlier, the fracture toughness of unaged and unirradiated wrought SSs and 

CASS materials fall in Category III, with JIc being above 150 kJ/m2 (857 in.-lb/in.2). Fracturing of 

these materials occurs after a stable crack extension at stresses well above the yield strength. 

However, neutron irradiation can degrade the fracture toughness of these materials to the level 

of Category II materials (i.e., JIc in the range of 30–150 kJ/m2 [171–857 in.-lb/in.2]) or even 

Category I materials (i.e., JIc < 30 kJ/m2 [< 171 in.-lb/in.2]). Therefore, failure in neutronirradiated materials may occur without general yielding, and either EPFM or LEFM is used for 

analyzing structural integrity and developing inspection guidelines for components fabricated 

from CASS materials. For wrought austenitic SSs and associated welds, the effect of neutron 

irradiation on the fracture toughness of these materials is estimated by defining a lower-bound 

curve expressed in terms of the fracture toughness parameters, such as the JIc value or 

coefficient C of the J-R curve, as a function of the neutron dose (in dpa).39,42 

A list of CASS components in LWR core internals and their expected neutron dose during 

60 years of service is presented in Table 6.44,93 Most of the components are fabricated from 

CF-8 material. The control rod guide tube (CRGT) spacer casting in Babcock & Wilcox (B&W) 

PWRs is fabricated from CF-3M. In General Electric (GE) BWRs, the CRGT base and 

low-pressure core injection (LPCI) coupling are fabricated from CF-3 or CF-8 materials. In the 

Combustion Engineering PWR, only the core support columns are fabricated from CF-8 

material. 

In an earlier study at ANL (NUREG/CR-7027),47 a critical assessment of the neutron 

embrittlement of wrought austenitic SSs and CASS materials was performed to establish the 

effects of material parameters (e.g., composition, thermo-mechanical treatment, microstructure, 

microchemistry, yield strength, stacking fault energy) and environmental parameters (e.g., water 

chemistry, irradiation temperature, dose, dose rate) on neutron embrittlement.46,47 The results 

were used to (a) define a threshold fluence level above which irradiation effects on the fracture 

toughness of cast and wrought austenitic SSs are significant and (b) evaluate the potential for

neutron embrittlement of these materials under LWR operating conditions. The results indicated

that for the same irradiation conditions, the fracture toughness of thermally aged CASS material

is lower than that of the heat-affected zone (HAZ) of SS base materials, which, in turn, is lower 

than that of solution-annealed SS base materials. 
74

The combined effects of thermal aging and neutron irradiation embrittlement were also 

discussed.46,47 However, the fracture toughness data available at that time were inadequate to 

accurately evaluate the combined effects. The significant results from the earlier study 

(i.e., NUREG/CR-7027) and some recent studies on potential combined effects of thermal and 

neutron embrittlement are summarized below. 

Table 6. LWR core internal components made of CASS materials and maximum neutron 

dose after 60 years of service (Refs. 44,93).

Component Material

60-Year

Dose (dpa)

Babcock & Wilcox (B&W) PWR

Control rod guide tube (CRGT) spacer castings CF-3M Not available

Core support shield outlet nozzle CF-8 Not available

Incore monitoring instrumentation guide tube spider CF-8 Not available

Combustion Engineering (CE) PWR

 Core support columns CF-8 0.15–1.50

 Control element assembly (CEA) shrouds CPF-8/CF-8 < 0.15

 CEA shroud base CF-8 0.15–1.05

 Modified CEA shroud expansion shaft guides CF-8 <0.15

Westinghouse PWR

 CRGT assembly lower flanges CF-8 1.05–1.50

 Mixing devices CF-8 1.05–1.50

 Upper head injection flow column base CF-8 1.05–1.50

 Upper support column base CF-8 1.05–1.50

 Bottom-mounted instrumentation columns cruciforms CF-8 1.50–7.50

 Lower internals assembly lower support casting CF-8 <0.15

 Lower internals assembly column bodies CF-8 1.50–7.50

General Electric (GE) BWR

 Orificed fuel support (OFS) CF-8 >0.45

 CRGT base CF-3/CF-8 <0.00015

 Core spray sparger nozzle elbows CF-8 <0.15

 Jet pump transition piece CF-8 >0.45

 Jet pump restrainer bracket CF-8 >0.45

 Jet pump inlet mixer assembly CF-8 >0.45

 Jet pump inlet elbow CF-8 >0.45

 Jet pump inlet nozzle CF-8 >0.45

 Jet pump diffuser CF-8 >0.45

 Low-pressure core injection (LPCI) coupling CF-3/CF-8 <0.75

5.1 Fracture Toughness of Irradiated Austenitic Stainless Steels

Until recently, most of the published experimental data on neutron embrittlement of austenitic 

SSs had been obtained on materials irradiated in high-flux fast reactors.94-99 In these studies, 

the embrittlement of the materials has been characterized in terms of tensile properties, Charpyimpact properties, and fracture toughness. The fracture toughness of structural materials is 

typically characterized by (a) the initiation toughness JIc and tearing modulus T for materials that 

fail after substantial plastic deformation (for EPFM analysis) and by (b) the critical stress 
75

intensity factor KIc for materials that fail after little or no deformation (for LEFM analysis). In 

some studies, the power-law J-R curve parameters, coefficient C and exponent n, are also 

reported. The fracture toughness data have been obtained from compact tension (CT) or 

single-edge bend [SE(B)] specimens, and, in a few cases, from chevron notch short rod 

specimens. To reduce activity and facilitate handling, small specimens (e.g., ≈8-mm-thick, 

1⁄4-T CT) have been used in several studies. For these specimens, J values above 150 kJ/m1/2

and crack extensions beyond about 1.2 mm are above the validity limits based on ASTM 

Specification E 1820-06. However, a comparison of fracture toughness data obtained on 

1-T CT and small-sized CT or SE(B) specimens show comparable J-versus-∆a values, even 

beyond the ASTM-defined validity limits.47,100 The small specimens yield equivalent J-R curve 

data at least for materials with JIc values up to about 300 kJ/m1/2 and maybe even higher. 

Plots of JIc or KIc and KJc as a function of neutron dose are generally used for developing 

screening criteria for neutron embrittlement. In ASTM Specification E 1820-06, JIc is determined 

from the intersection of the best-fit power-law J-R curve with the 0.2-offset line parallel to the 

blunting line. The blunting line is defined as 

J = mσf∆a, (67)

where σf is the flow stress, ∆a is the crack extension, and the constraint factor m is 2 or a value 

determined from the best fit of the experimental data. However, the analysis procedures,

described in the ASTM specifications for JIc determination, are not applicable to austenitic SSs 

because of their extremely high toughness, ductility, and strain-hardening ability. The main 

difference concerns the expression for the crack-tip blunting line. For austenitic SSs, a value of 

2 for m significantly over-predicts the crack extension due to crack blunting; therefore, it yields a 

non-conservative value of JIc.48,86 For austenitic SSs, a value of 4 for m better defines the 

blunting line. The constraint factor, M, which relates J to the crack tip opening displacement 

(CTOD) is given by the expression

J = Mσy(CTOD). (68)

The use of a higher value for M in Eq. 67 is consistent with the expected variation of M and σf

with strain hardening. The factor M is 1 for materials with intermediate to high strengths and low 

strain hardening, and it is 2 for materials with low strengths and high strain hardening, such as 

austenitic SSs. For the latter, the yield strength is approximately two-thirds of the flow stress,

and the crack extension associated with blunting is approximately one-third of CTOD.48 Thus, 

for such materials, the crack tip blunting line is given by

J = Mσy(CTOD) ≈ 2(2σf/3)(3∆a) = 4σf∆a, (69)

That is, Eq. 67 with M = 4. This relationship has been used to determine JIc in most 

investigations on neutron embrittlement.40,100 A value of 2 for M has also been used by some 

investigators.39 The latter typically yields a higher value of JIc for Category III materials 

(i.e., with a JIc >150 kJ/cm2). However, the difference in JIc values determined by using values 

of M of 2 or 4 is insignificant for Category II materials (i.e., with a JIc of <100 kJ/cm2). Because, 

it is primarily the cases in which the fracture toughness of irradiated austenitic SSs has been 

reduced to Category II levels that are of interest for embrittlement evaluations, the effect of 

differences in the procedure to determine JIc is likely to be insignificant. 

Another factor that may influence the reported values of JIc is the use of an effective yield stress 

instead of the measured yield stress. The K/size criteria were developed for materials that show 
76

work hardening; therefore, they may not be applicable for materials irradiated to fluence levels 

where, on a local level, they do not strain harden. An effective yield stress, in which the 

irradiation-induced increase in yield strength is discounted by a factor of 2 for moderately 

irradiated materials101 and by a factor of 3 for highly irradiated materials,102 has been proposed 

to define K/size criteria for moderately to highly irradiated materials. Some studies have used 

such a yield stress to determine JIc.100 Because JIc is a measure of fracture toughness at 

instability without a significant stable crack extension, the measured yield or flow stress of the 

irradiated materials seems more appropriate for JIc determinations. Nevertheless, the choice of 

measured or effective yield stress is likely to have an insignificant effect on the measured JIc of 

materials with poor fracture toughness. 

5.1.1 Fracture Toughness JIc

The effects of neutron exposure (in dpa) on the fracture toughness of austenitic SSs at 25–

427°C (77–842°F) have been investigated for SSs irradiated up to 90 dpa at 90–450°C (194–

842°F) in fast reactors.41,48,103–112 The irradiation and test temperatures, respectively (with a 

few exceptions), were 325°C and 25°C for the data obtained by Kim et al.,41 90–250°C and 25–

250°C for the data obtained by Alexander et al.,106 and 100–155°C and 125°C for the data 

obtained by Sindelar et al.107 As discussed earlier in NRC topical reports NUREG/CR-6960100

and NUREG/CR-7027,47 the fast reactor data show substantial decrease in toughness at 

exposures of 1–10 dpa, and little or no further reduction in toughness beyond 10 dpa. The 

degradation in fracture properties appear to saturates at a JIc value of ~30 kJ/m2 (171 in.-lb/in.2); 

that is, a KJc value of 75 MPa m1/2 (68.2 ksi in.1/2).47,100 In addition, the failure mode changes 

from dimple fracture to channel fracture. 

The fracture toughness JIc values for wrought and cast SSs irradiated in LWR,36-48,56,94-116 are 

shown in Fig. 50. The Westinghouse data for a heat of CASS CF-8 material irradiated to about 

6–12 dpa are not included in the figure, because the irradiations were carried out in a fast 

reactor and the tests were conducted at RT. As discussed below, fracture toughness at reactor

temperatures is expected to be lower. The fracture toughness data trend for LWR-irradiated 

materials is similar to the trend for the fast reactor data. Most of the fracture toughness JIc

values for austenitic SSs irradiated in LWRs (288–316°C [550-601°F]) fall within the scatter 

band of the data obtained on materials irradiated in fast reactors, even though the LWR 

irradiations were at lower temperatures. However, the extent of embrittlement and the rate of 

decrease in fracture toughness vary among the various materials. Typically, for the same 

irradiation conditions, the fracture toughness of thermally aged CASS material is lower than the 

toughness of HAZ material, and that, in turn, is lower than the fracture toughness of solutionannealed SSs.

The Japan Power Electric Engineering and Inspection Corp. (JAPEIC) data for Type 304 SS 

irradiated to 3.0–5.3 dpa at LWR temperatures show very poor fracture toughness.37 The JIc

values are below the lower-bound curve for the fast reactor data. For the material irradiated to 

4.5–5.3 dpa (shown as "+" in Fig. 50), 9 of 10 CT specimens showed no ductile crack extension, 

and the KIc values were 52.5–67.5 MPa m1/2 (47.7–61.4 ksi in1/2).37 In Fig. 50, the lowest 

fracture toughnesses with KIc or KJc values in the range of 36.8–40.3 MPa m1/2 (33.5–

36.6 ksi in.1/2) are for a Type 347 SS irradiated to 16.5 dpa in a PWR37 and for a Type 304 SS 

irradiated to 7.4–8.4 dpa in a BWR.45 

The material’s orientation also has a strong effect on fracture toughness. Fracture toughness 

J-R tests and microstructural and microchemistry characterization have been performed on 

Types 304 and 304L control-rod and top guide materials irradiated to 4.7–12.0 dpa in a BWR. 
77

All materials consistently show lower fracture toughness in the T-L (transverse-longitudinal) 

orientation than in the L-T orientation (shown as isosceles triangles with their bases to the left or 

right, respectively, for T-L and L-T orientations).39 The fracture toughness KIc values are lower 

than the limiting value of 55 MPa m1/2 (50 ksi in.1/2) that has been proposed by industry for flaw 

tolerance evaluations of irradiated austenitic SSs.38,39 The Type 304 control-rod material 

irradiated to 7.4–8.4 dpa, show poor fracture toughness (JIc is 40 kJ/m2 in L-T orientation and 

7.5 kJ/m2 in the T-L orientation). Microstructural characterization39 show a fine distribution of

the γ’ phase with sizes in a range of 2–10 nm (average of 4.4 nm), and the density is 1–3 × 

1022 m-3. The γ’ phase is not observed in the Type 304 top guide material; it might influence the 

fracture toughness of these materials. The γ’ phase has been observed at dose levels above 

4 dpa in cold worked (CW) Type 316 SS irradiated under the PWR conditions.115 

The lower fracture toughness along the T-L orientation has been attributed to the presence of 

stringers consisting of long, narrow particles oriented in the rolling direction. This microstructure

results in a long, narrow quasi-cleavage structure parallel to the crack advance, thereby 

accelerating the crack advance.39 The formation of the γ’ phase due to changes in the 

microchemistry of the material caused by neutron irradiation appears to play an important role in 

the neutron embrittlement of austenitic SSs. The low JIc of this material might be considered a 

special case of materials containing a high density of particles aligned in the rolling direction. 

Nonetheless, these results show that irradiated austenitic SSs, particularly those with material 

compositions that promote the formation of the γ’ phase, can have very low fracture-toughness 

values. The contributions that additional precipitate phases, voids, and cavities can make to 

fracture toughness need to be further investigated.

Figure 50. Change in fracture toughness JIc as a function of neutron exposure 

for LWR irradiated austenitic SSs. Dashed lines represent the scatter 

band for the fast reactor data on SSs irradiated at 350–450°C (Refs. 36–

40,42–48,56,94,100).
78

5.1.2 Fracture Toughness J-R Curve

Fracture toughness J-R curve data have been obtained for Types 304, 304L, and 316L SSs, 

including weld HAZs, and CF-3, CF-8, and CF-8M CASS materials irradiated in LWRs up to 

about 14 dpa,37-47,100 and irradiated in fast reactors to much higher dose levels. The change in 

the fracture toughness J-R curve with the neutron dose for Type 304 SS irradiated under LWR 

conditions and tested at reactor operating temperatures is shown in Fig. 51. The decrease in 

fracture toughness is quite rapid up to about 6 dpa, and the toughness continues to decrease 

moderately at higher dose levels. The effects of various parameters (e.g., material type and 

heat treatment; test and irradiation temperatures; neutron energy spectrum, flux, dose) are 

discussed next. 

Figure 51. Fracture toughness JIc as a function of neutron exposure for SSs 

(Refs. 45,100). 

5.1.2.1 Irradiation Conditions

Fast reactor irradiations were at fluxes and temperatures higher than those typically observed in 

LWRs and had a different spectrum; the irradiation temperatures were 350–427°C (662–801°F). 

To accurately determine the effects of the neutron spectrum, flux, and temperature on the 

fracture properties of these materials, data on the same heat of material irradiated in a fast 

reactor and in an LWR to a comparable neutron dose are needed, but such data are not 

available. Although the general data trends appear to be similar for fast reactor irradiations and 

LWR irradiations, the tensile property data indicate that the tensile strength is higher and the 

ductility is lower for the BWR-irradiated materials than for the materials irradiated in fast 

reactors.47,100 However, the existing data are inadequate to determine the individual 

contributions of the irradiation temperature, flux, and energy spectrum to the degradation of 

fracture properties in irradiated austenitic SSs. Therefore, fast reactor data should be used only 

for establishing data trends and not for establishing the extent of embrittlement. 

5.1.2.2 Material Type

Most of the J-R curve data on LWR-irradiated austenitic SSs have been obtained for Type 304 

and 304L SSs. Data on Type 316, 316L, 316CW, and 347 SSs are very limited. Similarly, there 

have been only a few J-R curve tests on LWR-irradiated weld HAZ materials and CASS 

materials. Some differences in the fracture toughness data trends appear for the various 

grades of wrought austenitic SSs, but these differences may be artifacts of the limited data. For 
79

example, the heat-to-heat variation for a particular grade may be comparable to the apparent 

differences between grades in the current data. A few select data from Fig 50 on wrought 

Types 304, 316, 304L, and 316L SS, Type 304/304L HAZ material, and sensitized Type 304 

SS, are plotted in Fig. 52. Note that different symbol colors are used for the low-C (green) and 

high-C (orange) grades of SSs. The results indicate that the toughness of the high-C grades 

decreases faster than that of the low-C grades. There is little or no effect of sensitization

treatment for high-C Type 304 SS. In addition, for the same irradiation conditions, the fracture 

toughness of the weld HAZ materials is lower than that of the solution-annealed materials. 

Example of fracture toughness J-R curves for irradiated, sensitized SS, SS weld HAZ material, 

and CASS CF-8M material, are shown in Fig. 53. However, these results are based on very 

limited data.

Figure 52. Change in fracture toughness JIc for a select data set as a 

function of neutron exposure for LWR irradiated austenitic 

SSs (Refs. 37–40,42,43,45–47,100).

The available data indicate that although the fracture toughness of unirradiated CW steels is 

lower than that of unirradiated solution-annealed steels, the decrease in the toughness of CW 

steels with neutron exposure is lower than and the JIc at saturation is higher than those values 

for irradiated solution-annealed steels.47 However, the available data for CW steels are from 

fast reactor irradiations at relatively high temperatures of 400–427°C (752–800°F). The 

saturation JIc for CW SSs is likely to be lower for irradiations at LWR operating temperatures 

(i.e., 290–320°C [554–608°F]) and the differences may not be significant.

Unirradiated, thermally aged CASS materials have a lower fracture toughness than do wrought 

austenitic SSs, and their fracture toughness generally decreases more rapidly with neutron 

exposure than does that of solution-annealed materials. However, the existing data indicate 

that the saturation toughness for the CASS materials is not significantly different from that of 

solution-annealed SSs; the same bounding curve for JIc is applicable for both wrought austenitic 

SSs and CASS materials. Although CF-8 or CF-3 materials are used in the construction of
80

LWR core internals, in the ANL study, initially, the only data for LWR-irradiated CASS were data 

on CF-8M material. The reason was that significant amounts of experimental data from several 

heats of CF-3/CF-8 material are needed to accurately establish the lower-bound fracture 

toughness, whereas a few tests on CF-8M material can provide the worst-case value of fracture 

toughness for CF-3/CF-8 materials. 

5.1.2.3 Test Temperature

The fracture toughness of unirradiated austenitic SSs is known to decrease as the test 

temperature is increased. The change in the JIc of irradiated SSs as a function of test 

temperature is plotted in Fig. 54 for several grades of SSs and welds irradiated in LWRs and 

fast reactors. The results indicate that the fracture toughness of austenitic SS welds is lower 

than that of wrought SSs. For example, the JIc values of a 308L weld irradiated to 0.7 dpa les 

then 200 kJ/m2, and the value is slightly higher at 250°C than at RT. The results also indicate 

that for wrought SSs, the fracture toughness of materials irradiated to relatively low dose 

(<5 dpa) decreases with increasing test temperature in most cases. However, for steels 

Figure 53.

Fracture toughness J-R curves 

for sensitized Type 304 SS, 

weld HAZ materials of Type 304 

and 304L SS, and CF-8M steel 

in high-purity water at 289°C 

(Ref. 47).

Figure 54.

Fracture toughness JIc of 

irradiated austenitic SSs and 

welds as a function of test 

temperature (Ref. 100). 
81

irradiated to more than 12 dpa, the test temperature has little effect on fracture toughness. Note 

that at neuron dose of 12 dpa, the toughness value is already low, which makes it difficult to 

discern definitive trends. The data also indicate differences in the fracture morphology of highly 

irradiated materials. At temperatures above 230°C (446°F), the failure mode is predominantly 

channel fracture, characterized by a faceted fracture surface. It is associated with highly 

localized deformation along a narrow band of slip planes, in which the initial dislocation motion 

along the narrow band clears away the irradiation-induced defect structure, creating a defectfree channel that offers less resistance to subsequent dislocation motion. The localization of the 

deformation ultimately leads to channel failure.

5.1.2.4 Test Environment

Nearly all of the existing fracture toughness data have been obtained from tests in air and on 

specimens that were fatigue precracked at relatively low load ratios (typically 0.1–0.2) in RT air. 

However, in reactor core components, cracks are initiated primarily by SCC and have 

intergranular morphology, whereas the fatigue precracks in fracture toughness tests are always 

transgranular). In addition, the corrosion/oxidation reaction could influence fracture toughness. 

For example, hydrogen generated from the oxidation reaction could diffuse into the material and 

change the deformation behavior by changing the stacking-fault energy of the material. To 

investigate potential effects of the reactor coolant environment on the fracture toughness of 

austenitic SSs and CASS materials, J-R curve tests have been conducted on these materials in 

a BWR normal water chemistry (NWC) environment100 and in low-DO, high-purity water or 

simulated PWR environments.91 The effect of the reactor coolant environment on the fracture 

toughness of CASS materials was discussed earlier in Section 2.4.3.1. 

The results indicate that both NWC BWR and simulated low-DO PWR environment can 

decrease the fracture toughness of these materials. However, the effect may be insignificant for 

materials with poor fracture toughness (i.e., JIc values of <150 kJ/m2).46,47,91,100 For example, 

the fracture toughness J-R curves for irradiated Type 304L SAW HAZ in air and water 

environments are essentially identical (Fig. 55). However, for a CF-8M material aged for more 

than 15 years at 350°C, the J-R curve data for specimens precracked in air at 54°C and then 

tested in an shutdown water chemistry PWR environment at 54°C are significantly lower than 

the data for those specimens tested in air (Fig. 24). The specimens precracked in PWR water 

Figure 55.

Fracture toughness J-R 

curves for irradiated 

specimens of Type 304L 

SAW HAZ in air and NWC 

BWR environment (Ref. 47).
82

at 315°C and tested in PWR water also show reduced fracture toughness, but the effect is 

less.80 The significant decrease in fracture toughness is attributed to the synergism between 

hydrogen embrittlement and thermal embrittlement. Similarly, J-R curve data for Type 316L gas 

tungsten arc (GTA) welds indicated that the reactor coolant environment could decrease the 

fracture toughness by up to 40% relative to that in air.117 

The potential contribution of hydrogen-induced embrittlement has also been observed in the 

thermal embrittlement study at ANL. The J-R curves for the two tests on 1⁄4-T CT specimens of 

thermally aged and irradiated CF-8M steel in NWC BWR water are shown in Fig. 56. 

Unfortunately, companion tests in air were not conducted on the irradiated material. However, 

the fracture toughness J-R curve obtained for 1-T CT specimens of unirradiated, thermally aged 

material are included in the figure. In the two tests in water, large load drops, accompanied by

crack extensions of up to 0.5 mm in one specimen and 1.0 mm in the other, were observed at 

the onset of these crack extension. Such load drops are not typically observed during tests in 

air.16 Thus, although available fracture toughness data in reactor coolant environments are 

inclusive, the limited data suggest that there could be environmental effects on the fracture 

toughness of CASS material and austenitic SS welds, at least for materials with moderate or 

superior fracture toughness. Additional tests on irradiated CASS materials or SS welds in air 

and water environments are needed to determine the possible effects of LWR coolant 

environments on their fracture toughness.

Figure 56.

Fracture toughness J-R 

curves for thermally aged 

and irradiated CF-8M steel 

(Ref. 47). 

5.1.2.5 Irradiation Temperature

The available data are not adequate to establish accurately the effects of the irradiation 

temperature on the fracture toughness of austenitic SSs. However, tensile data for austenitic 

SSs indicate that irradiation hardening is highest, and ductility loss is at its maximum at an 

irradiation temperature of ~300°C (~572°F).118 Thus, the JIc values for all materials irradiated at 

temperatures above 350°C (662°F) (e.g., fast reactor irradiations), particularly for neutron 

exposures of more than 20 dpa, should be greater than the JIc values for materials irradiated at 

temperatures of 290–320°C (554–608°F). As mentioned before, to accurately evaluate the 

potential effects of irradiation temperature on the fracture properties of austenitic SSs and 

CASS materials, fracture toughness data are needed for a specific heat of material irradiated in 

LWRs at temperatures of 280–370°C (536–798°F). 
83

5.2 Lower-Bound Fracture Toughness Curve

In NUREG/CR-7027, the available fracture toughness data on wrought and cast austenitic SSs 

and associated welds irradiated in fast reactors or LWRs were reviewed and evaluated to define 

the lower-bound fracture toughness JIc value or coefficient C of the J-R curve as a function of 

neutron dose (in dpa).46,47 The lower-bound curves represent the change in fracture toughness 

parameters, such as the coefficient C of the power-law J-R curve and the corresponding JIc

value, as a function of neutron dose. The trend curve considers the following:

(a) The threshold neutron exposure for radiation embrittlement of austenitic SSs and a 

minimum fracture toughness for these materials irradiated to less than the threshold 

value,

(b) The saturation neutron exposure and a saturation fracture toughness for materials 

irradiated to greater than this value, and

(c) A description of the change in fracture toughness between the threshold and saturation 

neutron exposures.

The change in initiation toughness JIc of (a) wrought austenitic SSs and (b) CASS materials and 

weld metals as a function of neutron exposure (dpa) is shown in Fig. 57. The change in the 

lower-bound JIc value as a function of the neutron dose (dpa) is given by 

JIc = 7.5 + 110 exp[–0.35(dpa)1.4]. (70)

Note that the JAPEIC data on Type 304 SS only is not bounded by the lower bound curve; the 

data were obtained on short rod specimens and not the standard fracture toughness CT 

specimens. The lower-bound curve is defined essentially by the austenitic SS weld data. The 

lower-bound curve represents the following:

(i) Threshold dose of about 0.3 dpa for neutron embrittlement, 

(ii) Minimum fracture toughness JIc of ~116 kJ/m2 for neutron doses below 0.1 dpa, 

(iii) Saturation threshold of about 5–7 dpa beyond which the fracture toughness of these 

materials appears to saturate, 

(iv) Saturation fracture toughness JIc of 7.5 kJ/m2 (or KIc or KJc of 38 MPa m1/2), and 

(v) Description of the change in toughness between 0.1 and 10 dpa. 

The JIc value of ~116 kJ/m2 for neutron doses below the threshold dose is appropriate for 

thermally aged and unaged CASS materials and SS flux welds. A value that is higher than 

116 kJ/m2 may be considered for the minimum fracture toughness JIc for wrought austenitic SSs 

irradiated below the threshold dose for neutron embrittlement. However, appropriate 

justification for using a higher value should be provided. The description of the change in 

fracture toughness below the threshold value would also change accordingly. The saturation JIc

value of 7.5 kJ/m2 does not change; it is the same for wrought and cast SSs and their welds. 

The KJc (MPa m1/2) values determined from the lower-bound trend curve given by Eq. 70 are 

comparable to those predicted from the MRP lower-bound model proposed for PWRs42 at 0.3 
84

and 7.0 dpa. The MRP model bounds all the fracture toughness data from fast reactors, BWRs, 

and PWRs and is given by the expression, 

KJc = 180 – 142[1–exp(–dpa)]. (71)

The existing fracture toughness JIc data at 290–320°C for CASS materials irradiated under LWR 

conditions are plotted as a function of neutron dose in Fig. 58.37,41,42,80,95,98,100,109,117,119,120 

Note that the fast-reactor irradiated data for a heat of CF-8 material (slashed square symbols) 

are included in the figure because they have been used for evaluating neutron embrittlement of 

CASS CF-8 materials in PWRs. Furthermore, the data were obtained at RT. Therefore, as 

shown in Fig. 54, the actual fracture toughness of moderate to high toughness materials is 

expected to be lower at reactor temperatures. The fracture toughness data obtained at ANL on 

neutron irradiated CASS materials in LWR environments and the data obtained earlier on these 

Figure 57. Change in initiation toughness JIc of (a) wrought austenitic SSs and 

(b) CASS materials and weld metals as a function of neutron exposure. 

The data points plotted at 0.005 dpa are for unirradiated materials (Ref. 47). 
85

materials in air are listed in Table 7. Note that the recent data obtained at ANL were for CASS 

materials irradiated to a neutron dose of 0.08 dpa. This irradiation level was selected to help 

understand the combined effects of thermal and neutron embrittlement on SSs with a duplex 

structure, consisting of both austenite and ferrite phases. It is well-established that at an 

irradiation dose of about 0.1 dpa, the neutron embrittlement of the ferrite phase is essentially 

complete, but the embrittlement of the austenite phase occurs at irradiation levels above a 

threshold value of 0.3 dpa. In addition, data on materials irradiated to less than 0.1 dpa are 

needed to accurately evaluate the possible effects of the synergism between thermal and 

neutron embrittlement of CASS materials and their welds. 

Equations. 70 and 71 predict a saturation fracture toughness KIc of 38 MPa m1/2. For materials

irradiated below the threshold dose for irradiation embrittlement, Eq. 70 predicts a minimum KJc

of about 151 MPa m1/2, but the MRP (Eq. 71) expression predicts fracture toughness values that 

for some materials, such as SS weld HAZ, may be higher than the minimum toughness of the 

materials in the unirradiated condition. The existing data for BWR-irradiated austenitic SSs is 

not bounded by the disposition curve proposed by EPRI for BWRs. For example, at neutron 

doses of <0.7 dpa, the JIc values based on the EPRI curve are higher than the minimum JIc of 

some heats of wrought SSs and most thermally aged CASS with >15% ferrite.16 In addition, the 

saturation KIc of 55 MPa m1/2 at 4.5 dpa for the EPRI curve is also higher than the value of 

38 MPa m1/2 previously proposed by MRP for PWRs.42 The saturation KIc for the EPRI curve 

was based on data for which the specimen orientation was unknown. As discussed above, 

recent data indicate that fracture toughness in the transverse orientation is nearly half of that in 

Figure 58. Plots of fracture toughness JIc values as a function of neutron dose for 

(a) austenitic SS welds, (b) CASS materials, and (c) austenitic SS HAZ. 

Solid line represents the lower-bound JIc values proposed in NUREG/CR-7027. 

The data points plotted at 0.007 dpa are for unirradiated materials.
86

the longitudinal orientation.39 Therefore, the bounding KIc values above 4.5 dpa are likely to be 

lower than 55 MPa m1/2. 

A fracture toughness J-R curve may be used to analyze material behavior for loading beyond 

JIc. The J-R curve is expressed in terms of the J integral and crack extension (∆a) by the power 

law J = C(∆a)n. At dose levels below the threshold dose for saturation (i.e., at dose levels less 

than ~7 dpa), the effect of neutron irradiation on the fracture toughness of austenitic SSs can be 

represented by a decrease in the coefficient C of the power-law correlation for the J-R curve 

with neutron dose. The variation of the fracture toughness coefficient C as a function of neutron 

dose for the data shown in Fig. 58 is plotted in Fig. 59. One curve in the figure represents the 

disposition curve proposed by EPRI for BWRs,38 and the other represents a trend curve

proposed in NUREG/CR-7017 for coefficient C that bounds the existing data. For neutron dose

less than 5 dpa, the existing fracture toughness data are bounded by the following expression

for C:

C = 25 + 175 exp[–0.35(dpa)1.4], (72)

and an exponent n equal to 0.37 (i.e., median value of the experimental data). The exponent n 

of the power-law curve typically ranges from 0.35 to 0.70 for unirradiated materials and 0.16 to 

0.65 for irradiated materials. Unlike the behavior seen for thermally aged cast austenitic SSs (in 

which exponent n typically decreases with a decrease in fracture toughness),16 no obvious trend 

of n with fluence is evident. Based on the material and irradiation conditions, a conservative 

value of 0.3 for exponent n may be used to evaluate the neutron embrittlement of these 

materials. Equation 72 yields a minimum C value of 192 kJ/m2 (1094 in.-lb/in.2) for materials 

Table 7 Fracture toughness J-R curve data on irradiated CASS CF-3, CF-8, and CF-8M 

materials in air and LWR environments. 

Grade Heat

Material 

Condition

Unirradiated Material 

in Air at 290°C

Unirradiated Material in 

Low-DO Water at 320°C

Irradiated Materiala in

Low-DO Water at 320°C

C n JIc (kJ/m2

) C n JIc (kJ/m2) C n JIc (kJ/m2)

CF-3 69 (21%) Unaged 756 0.31 700 536 0.68 320 430 0.64 204

CF-3 69 (21%) Unaged 425 0.54 266 – – – – – –

CF-3 69 (21%) Aged 296 0.51 167 353 0.66 170 362 0.85 116

CF-3 52 (14%) Unaged – – – – – – 347 0.65 168

CF-3 52 (14%) Aged – – – – – – 419 0.80 161

CF-8 68 (15%) Unaged 783 0.27 753 - - >500 359 0.57 183

CF-8 68 (15%) Aged 396 0.51 242 395 0.58 220 372 0.62 171

CF-8 61 (13%) Aged – – – – – – 406 0.60 205

CF-8M 75 (25%) Unaged 583 0.45 437 – – – 336 0.66 145

CF-8M 75 (25%) Unaged 600 0.35 493 – – – – – –

CF-8M 75 (25%) Aged 274 0.46 156 – – – 259 0.64 106

CF-8M 75 (25%) Aged 364 0.32 262 – – – – – –

CF-8M 75 (25%) Aged – – – – – – 120b 0.24 84

CF-8M 75 (25%) Aged – – – – – – 80b 0.45 40 a All specimens were irradiated to a neutron dose of 0.08 dpa at 315°C and tested in low-DO high-purity water or 

simulated PWR water at 320°C, except for the last two specimens (Heat 75), which were irradiated to 2.46 dpa at 

297°C and tested at 289°C in high-purity water with 400 parts per billion (ppb) DO. b Tested at 289°C in high-purity water containing 400 ppb DO.
87

irradiated to less than 0.1 dpa and a minimum C value of ~31 kJ/m2 (~177 in.-lb/in.2) for 

materials irradiated to 7 dpa. 

For the data shown in Figs. 58 and 59, the J-integral values at a crack extension of 2.5 mm, J2.5,

are plotted as a function of neutron dose in Fig. 60. The solid curve in the figure represents the 

J2.5 values that bound the existing experimental data. The curve was obtained by using the 

power-law J-R curve relationship, with coefficient C determined from Eq. 72 and the median 

value of 0.37 for exponent n. The lower-bound curve indicates that for CASS materials 

irradiated up to 0.5 dpa, the predicted J2.5 values are above the screening value of 255 kJ/m2

(1456 in.-lb/in.2). 

Note that most of the J-R curve data for neutron irradiated SSs have been obtained on 1⁄2-T or 

1⁄4-T CT specimens that were about 6-mm thick. Therefore, the validity of the fracture 

toughness data using the small CT specimens needs to be assessed. The fracture mechanics 

approach correlates the behavior of components with that of specimens by using the K 

parameter. It considers that if the two cracks have the same K, then they have the same strains

and stresses in the region near the crack tip. The ASTM specifications for specimen K/size 

criteria are intended to ensure that the plastic zone is small enough and K is controlling the 

crack behavior. It has been often argued that since the K/size criterion was developed for 

materials that show work hardening and it may not be applicable for materials that are irradiated 

to fluence levels where, on a local level, they do not strain harden and exhibit strain softening. 

Recent investigations have evaluated the validity of the K/size criterion for irradiated materials 

by comparing the plastic strain distribution in a 1⁄2-T CT specimen estimated from finite element 

method calculations with experimentally observed plastic deformation area.121,122 The plastic 

Figure 59. Coefficient C of the J-R curve as a function of neutron dose for 

CASS materials. Solid line represents the lower-bound C values 

proposed in NUREG/CR-7027. The data points plotted at 0.007 dpa 

are for unirradiated materials.
88

zone size was estimated to be 0.2–0.4 mm at K = 30 MPa m1/2.121 The results indicate that for 

an austenitic SS irradiated to 3 × 1021 n/cm2, the appropriate K range is at least 30 MPa m1/2 for 

a (5.8-mm thick) CT specimen. 

Figure 60 shows the results of two tests of CF-8M material thermally aged for 10,000 h at 400°C 

and then irradiated to well above the threshold dose for neutron embrittlement (shown as closed 

circles). The resulting J2.5 values for these two tests are bounded by the proposed lower-bound 

J-R curve. As discussed above, since only CF-3/CF-8 and, in a few cases, CF-3M CASS 

materials are used for designs of all BWRs and PWRs, the data for CF-8M represent the worstcase values. Actual values for CF-3/CF-8 materials would be higher. However, there is little or 

no data on LWR-irradiated CF-3 and CF-8 materials to accurately establish the lower-bound J-R 

curves for these materials during service in LWRs. The only data for CF-8 material is for fast 

reactor irradiation. The existing data indicate that for the same neutron dose, the embrittlement 

of LWR irradiated materials is greater than that of materials irradiated in a fast reactor. In 

addition, the CF-8 data are on materials irradiated at 325°C; limited data indicate that the extent 

of embrittlement is greater under BWR service conditions than PWR service conditions. 

5.3 Methodology for Incorporating Irradiation Effects on CASS Materials 

including the Combined Effects of Thermal and Neutron Embrittlement

5.3.1 Threshold Neutron Dose for Irradiation Effects

To account for the effects of thermal aging and neutron irradiation embrittlement on the fracture 

toughness of reactor core internal components, the NRC staff has proposed an aging 

Figure 60. Fracture toughness J2.5 values as a function of neutron dose for 

CASS materials. Solid line represents the lower-bound J2.5 values 

proposed in NUREG/CR-7027. The data points plotted at 0.007 dpa 

are for unirradiated materials.
89

management program (AMP) for license renewal.123 The program does not directly monitor for 

loss of fracture toughness that is induced by either thermal or neutron irradiation embrittlement. 

Instead, the impact of a loss of fracture toughness on component integrity is indirectly managed 

by using visual or volumetric examination techniques to monitor for cracking in the components. 

If cracking is detected in the components, a flaw tolerance evaluation is performed by using 

acceptable reduced fracture toughness properties. 

The AMP for PWR vessel internals follows the guidance found in EPRI report MRP-227.124 The 

AMP states that a loss of fracture toughness due to thermal and/or neutron embrittlement of 

CASS materials can occur as a result of exposure to neutron fluence of ˃1019 n/cm2 (E of 

>1 MeV) (i.e., 0.015 dpa) or if CASS material is more susceptible to thermal embrittlement. A 

fracture toughness value of 255 kJ/m2 (1450 in.-lb/in.2) at a crack extension of 2.5 mm (0.1 in.) 

is used to differentiate between CASS materials that are not susceptible and those that might be 

susceptible to thermal embrittlement. The screening criteria to determine the susceptibility of 

CASS components to thermal aging embrittlement are outlined in Table 1.51 Based on the 

review and evaluation of the current fracture toughness data of thermally aged CASS materials, 

a proposed revision of the screening criteria is presented in Table. 5. 

Regarding the neutron dose threshold above which the potential combined effects of thermal 

and neutron embrittlement are significant and need to be evaluated, the lower-bound curve

shown in Fig. 60 indicates that for CASS materials irradiated up to 0.5 dpa, the predicted J2.5

values are above the screening value of 255 kJ/m2 (1456 in.-lb/in.2). If needed, the lower-bound 

fracture toughness curves described above can be used to preform a flaw tolerance evaluation. 

However, note that the fracture toughness of SS weld metals may be significantly lower than 

this threshold value (see Fig. 57). 

5.3.2 Potential Effects of Thermal and Neutron Embrittlement

The embrittlement of the ferrite phase because of neutron irradiation occurs at lower dose levels 

than does embrittlement of the austenite phase. A shift in the nil-ductility transition (NDT) 

temperature of up to 150°C (302°F) has been observed in pressure vessel steels irradiated to 

0.07–0.15 dpa.125 Thus, embrittlement of ferrite is expected to occur at 0.05–0.50 dpa, whereas 

any significant neutron embrittlement of the austenite phase occurs only at above ~0.4 dpa 

(Fig. 58-60). In recent studies at ANL, fracture toughness tests have been conducted in LWR 

environments on unaged and aged heats of CF-3, CF-8, and CF-8M materials that were either 

in an unirradiated condition or irradiated to a neutron dose of 0.08 dpa at 315°C in the Halden 

reactor. The results are shown in Fig. 61. The ferrite contents of the CF-3, CF-8, and CF-8M 

materials, determined from Hull’s equivalent factors were, 21.0%, 14.9%, and 24.8%, 

respectively. The results indicate that only the JIc values are slightly lower for the aged and 

irradiated materials than those that were only aged or irradiated. The values of coefficient C 

and J2.5 show no effect from combined thermal and neutron embrittlement. 

Similarly, the fracture toughness data for two other heats of thermally aged and irradiated CF-8 

material (Heats 52 and 61, containing 14% and 13% ferrite, respectively) yield J2.5 values that 

are significantly above 255 kJ/m2. Therefore, the existing data indicate little or no combined 

effect from thermal and neutron irradiation. Furthermore, the fracture toughness (J2.5) values of 

aged CASS CF-3 and CF-8 materials irradiated to a neutron dose of less than 0.5 dpa are 

above the screening value of 255 kJ/m2 (1456 in.-lb/in.2) proposed by EPRI.93 
90

Figure 61.

Comparison of the fracture 

toughness JIc, coefficient, and J2.5

value obtained in air and LWR 

environment at 290–320°C of CF-3, 

CF-8, and CF-8M materials in the 

unaged and aged as well as 

unirradiated and irradiated 

conditions. 
91

6 SUMMARY

The procedure and correlations presented earlier in NUREG/CR-4513, Rev. 1, for predicting the 

Charpy-impact energy and fracture toughness J-R curve of aged CASS CF-3, CF-3M, CF-8, 

and CF-8M materials from known material information have been updated by using a much 

larger database. The applicability of the methodology has been extended to materials with 

ferrite contents of up to 40%. In addition, for CASS materials used in the reactor core support 

structure and core internal components, recommendations are provided for evaluating the 

combined effects of thermal and neutron embrittlement.

As in NUREG/CR-4513 Rev. 1, the fracture toughness and tensile properties of a specific CASS 

material are estimated from the extent and kinetics of thermal embrittlement. Thermal 

embrittlement of CASS materials is characterized in terms of RT Charpy-impact energy. Thus, 

the extent of thermal embrittlement represents the change in Charpy-impact energy. The extent 

of thermal embrittlement at “saturation” (i.e., the minimum impact energy that can be achieved 

for the material after long–term aging) is determined from the chemical composition of the steel

and its ferrite content. The Charpy-impact energy as a function of the time and temperature of 

the reactor service is estimated from the kinetics of thermal embrittlement, which are expressed 

by the activation energy for the degradation of Charpy-impact energy due to thermal aging. The 

activation energy is also determined from the chemical composition of the material and ferrite 

content. The initial impact energy of the unaged steel is required for these estimates. The 

fracture toughness J-R curve for the material (expressed by coefficient C and exponent n) is 

then obtained from correlations between the RT Charpy-impact energy and fracture toughness 

parameters. A common lower-bound J-R curve for CASS materials with an unknown chemical 

composition is also defined for a given grade of material, range of ferrite contents (e.g., <10%, 

>10–15%, >15–20%, >20–25%, >25–30%, and >30–40%), and temperature. The method for 

estimating the mechanical properties of CASS materials during reactor service is described. 

For CASS materials used in the reactor core support structures and core internal components, 

the available data are inadequate to definitively establish the effects of thermal and neutron 

embrittlement of various CASS materials as a function of service time and temperature. The 

combined effects of thermal and neutron embrittlement are estimated from the lower-bound 

fracture toughness curves expressed as a function of neutron dose. The fracture toughness is 

defined in terms of the coefficient C, exponent n, and JIc of the fracture toughness J-R curve. 

However, the existing data are inadequate to definitively determine the combined effects of 

thermal and neutron embrittlement of CASS materials. Experimental data on aged material 

irradiated in LWRs to neutron doses <0.01 dpa are needed to better define such effects. 

The tensile yield and flow stresses and the Ramberg/Osgood parameters for tensile strain 

hardening are estimated from the flow stress of the unaged material and the kinetics of 

embrittlement. The fracture toughness JIc values for aged CASS materials are then determined 

from the estimated J-R curve and flow stress. Only the chemical composition, initial Charpyimpact energy, and flow stress of the unaged material are needed for the estimates.

The significant differences between NUREG/CR-4513 Rev. 1 and this report are as follows: 

(i) Embrittlement-Charpy-impact Energy: Eqs. 18–26 correspond to Eqs. 3.2.4–3.2.12 of 

Rev. 1; Eqs. 21 and 24 are updated versions of Eqs. 3.2.7 and 3.2.10, all others are the 

same. For CF-8M materials, the correlation between the RT Charpy-impact energy and 

material parameter φ was revised; the effect is significant for CF-8M materials with Ni 

content of ≥10%.
92

(ii) Embrittlement-Fracture Toughness J-R Curve: Eqs. 27–44 correspond to Eqs. 3.2.13–

3.2.26 of Rev. 1. Eqs. 29 and 35 are new and Eqs. 39–44 are updated versions of 

3.2.15, 16, 19, 22,23, and 26. 

For CF-8M materials, the correlations between the RT Charpy-impact energy and 

coefficient C of the J-R curve at RT and at 290–320°C have been extended to include 

CASS materials with a ferrite content of up to 40%. The new correlations are applicable 

to materials with relatively poor RT Charpy-impact energies (i.e., <35–45 J/m2). In 

addition, the correlations between the RT Charpy-impact energy and exponent n of the 

J-R curve at RT and at 290–320°C have been revised. Estimates of n made from using 

the updated expressions are slightly lower, particularly for CF-8 materials.

(iii) Minimum Fracture Toughness of Unaged CASS Materials: Eq. 45 is the same as 

Eq. 3.2.27 of Rev. 1 and Eq. 46 is an updated version of Eq. 3.2.28. The minimum 

fracture toughness J-R curve for centrifugally cast CASS materials, was revised; the 

coefficient C of the J-R curve was decreased from 650 to 550. 

(iv) New lower-bound curves are presented for correlating the saturation RT Charpy-impact

energy and the ferrite content for CF-3, CF-3M, CF-8, and CF-8M materials. These 

correlations are used to define the lower-bound J-R curves for CASS materials 

containing ferrite in a specific range (e.g., <10%, >10–15%, >15–20%, >20–25%, 

>25–30%, and >30–40%). 

(v) Recommendations are provided for estimating the lower-bound fracture toughness 

curves for CASS materials used in the reactor core support structures and core internal 

components.

These updated expressions for estimating fracture toughness of CASS materials during reactor 

service have the following impact on the criteria proposed by NRC (Table 1) for determining the 

susceptibility of various categories of CASS components to thermal aging embrittlement. Based 

on the casting process and whether the materials contains low Mo (0.5 wt.% max.) or high Mo

(2.0–3.0 wt.%), the proposed criteria specify the ferrite content above which the material would 

be susceptible to thermal embrittlement. The updated criteria are presented in Table 5. 

• The criteria for low-Mo CF-3 and CF-8 materials have not changed. All centrifugally cast 

materials and static cast materials containing ≤20% ferrite are not susceptible to thermal 

embrittlement. Only static cast materials containing >20% ferrite are potentially 

susceptible.

• The criteria for CF-8M materials depend on whether the material contains ≥10 wt.% Ni. 

- The criterion for static cast CF-8M materials containing <10% Ni has not changed. 

Static cast materials with ≤14% ferrite are not susceptible and with >14% ferrite are 

potentially susceptible. 

- The criterion for centrifugally cast CF-8M materials containing <10% Ni has been 

revised. The threshold value of ferrite content has been decreased from 20% to 19% 

ferrite. Centrifugally cast materials with ≤19% ferrite are not susceptible and with 

>19% ferrite are potentially susceptible to thermal embrittlement. 

- The criterion for static cast CF-8M materials containing ≥10% Ni has been revised. 

The threshold value of ferrite content has been decreased from 14% to 11% ferrite. 

Static cast materials with ≤11% ferrite are not susceptible and with >11% ferrite are 

potentially susceptible to thermal embrittlement. 
93

- The criterion for centrifugally cast CF-8M materials containing ≥10% Ni has been 

revised. The threshold value of ferrite content has been decreased from 20% to 13% 

ferrite. Centrifugally cast materials with ≤13% ferrite are not susceptible and with 

>13% ferrite are potentially susceptible to thermal embrittlement. 

The methodology presented in this report is only applicable to service times that are equivalent 

to 10,000 h at 400°C. This corresponds to 

• ≥125 efpy at 290°C for CF-8/CF-3 materials, and 

• ≥30 efpy at 320°C for CF-8/CF-3 and ≥15 efpy for CF-8M materials used within primary 

pressure boundary components, and 

• ≥15 efpy at 350°C for CF-8/CF-3 materials used in the reactor core internals. 

Additional long-term aging data are needed to estimate fracture properties for longer service 

times. Furthermore, this methodology may not be applicable for CF-8M materials with more 

than a trace amount of Nb, particularly for materials containing >15% ferrite. The methodology 

also does not consider the potential effect of reactor coolant environment on fracture toughness. 

Limited data indicate significant effect of environment, particularly at low temperatures (e.g., 

shutdown water chemistry at 54°C). In addition, the existing fracture toughness data on LWRirradiated CF-8/CF-3 materials is inadequate to accurately establish the lower-bound J-R curves 

for these materials as a function of neutron dose.

95

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A-1

APPENDIX A: MATERIAL INFORMATION

The various grades of CASS materials and their product form, heat designation, chemical composition, and mec

such as Charpy-impact energy, tensile properties, and fracture toughness J-R curves of materials in the as-cast 

thermal aging in the laboratory at temperatures between 290 and 400°C up to 60,000 h are presented in the foll

Table A1. The chemical composition, product form, and ferrite content of the various CASS materials included in 

Heat Chemical Composition (wt.%)* Ferrite (%)

ID Process Product C Mn Si P S Ni Cr Mo N Calc. Mea

Grade CF-3

47 Static Keel block 0.018 0.60 1.06 0.007 0.006 10.63 19.81 0.59 0.028 8.4 16.3 

48 Static Keel block 0.01 0.60 1.08 0.009 0.006 10.46 19.55 0.30 0.072 5.1 - 

49 Static Keel block 0.01 0.60 0.95 0.010 0.007 10.69 19.41 0.32 0.065 4.4 - 

50 Static Keel block 0.34 0.60 1.10 0.016 0.007 9.14 17.89 0.33 0.079 6.2 - 

51 Static Keel block 0.010 0.63 0.86 0.014 0.005 9.06 20.13 0.32 0.058 14.3 18.0 

52 Static Keel block 0.009 0.57 0.92 0.012 0.005 9.40 19.49 0.35 0.052 10.3 13.5 

P3 Centrifugal Pipe 0.58 m OD 0.021 1.06 0.88 0.017 0.014 8.45 18.89 0.01 0.168 - - 

P2 Centrifugal Pipe 0.93 m OD 

73-mm wall 0.019 0.74 0.94 0.019 0.006 9.38 20.20 0.16 0.040 12.5 15.6 

I Static Pump impeller 0.019 0.47 0.83 0.030 0.011 8.70 20.20 0.45 0.032 20.4 17.1 

69 Static Slab/Plate 0.023 0.63 1.13 0.015 0.005 8.59 20.18 0.34 0.028 21.0 23.6 

EPRI Static - 0.030 0.74 0.84 - - (7.93) 22.04 0.23 0.045 36.0 32.0 

284 Static - 0.025 0.28 0.52 - - 8.23 23.00 0.17 0.037 43.6 42.0 

280 Static - 0.028 0.50 1.37 0.015 0.006 8.00 21.60 0.25 0.038 36.3 38.0 

B1 Static - 0.025 0.40 0.68 - - 9.06 19.49 0.23 0.027 11.4 12.5 

B2 Static - 0.025 0.40 0.68 - - 8.69 21.38 0.23 0.027 26.3 23.0 

B3 Static - 0.026 0.40 0.72 - - 8.42 22.78 0.23 0.029 41.8 37.5 

TWI Static Plate 0.030 0.42 0.69 0.025 0.001 8.50 19.90 0.28 0.025 17.2 19.0 

FA Static - 0.021 1.14 0.99 0.037 - 8.90 18.90 0.10 0.074 6.0 6.3 

F3329 Static - 0.030 0.82 1.43 - - 8.20 21.40 0.03 0.040 28.4 - 

Grade CF-3M with ≥10% Ni

C5 Static - 0.020 0.70 0.99 - - 10.60 19.30 2.38 0.040 14.1 10.0 

FD Static - 0.026 1.12 0.94 - - 10.32 19.15 2.44 0.063 11.8 13.9 

FI Centrifugal - 0.020 0.70 0.98 - - 10.69 19.36 2.40 0.039 14.1 15.5 
A-2

Table A1. (Contd.)

Heat Chemical Composition (wt.%)* Ferrite (%)

ID Process Product C Mn Si P S Ni Cr Mo N Calc. Mea

C Static Elbow C 0.026 1.03 1.25 - - 10.24 21.90 2.68 0.040 35.5 - 

EL Static 90°elbow EL 0.030 1.06 1.15 - - 10.30 21.85 2.72 0.039 33.5 - 

Sc Static Sc2/3 elbow 0.024 1.09 1.21 - - 10.45 22.10 2.70 0.037 35.9 - 

Grade CF-8

53 Static Keel block 0.065 0.64 1.16 0.012 0.009 9.23 19.53 0.39 0.049 6.4 - 

54 Static Keel block 0.063 0.55 1.03 0.011 0.005 9.17 19.31 0.35 0.084 4.1 - 

56 Static Keel block 0.066 0.57 1.05 0.007 0.007 9.28 19.65 0.34 0.030 7.3 10.1 

57 Static Keel block 0.056 0.62 1.08 0.009 0.004 9.27 18.68 0.34 0.047 4.4 - 

58 Static Keel block 0.056 0.62 1.12 0.010 0.005 10.89 19.53 0.33 0.040 3.2 - 

59 Static Keel block 0.062 0.60 1.08 0.008 0.007 9.34 20.33 0.32 0.045 8.8 13.5 

60 Static Keel block 0.064 0.67 0.95 0.008 0.006 8.34 21.05 0.31 0.058 15.4 21.1 

61 Static Keel block 0.054 0.65 1.01 0.007 0.007 8.86 20.65 0.32 0.080 10.0 13.1 

68 Static Slab/Plate 0.063 0.64 1.07 0.021 0.014 8.08 20.64 0.31 0.062 14.9 23.4 

73 Static Slab/Plate 0.070 0.72 1.09 0.028 0.016 8.54 19.43 0.25 0.053 7.1 7.7 

C1 Static Pump Casing 0.039 1.20 1.18 0.033 0.008 9.37 19.00 0.65 0.040 7.9 2.2 

P1 Centrifugal Pipe 0.89 m OD 

73-mm wall 0.036 0.59 1.12 0.026 0.013 8.10 20.49 0.04 0.057 17.6 24.1 

CC4 Static - 0.056 1.11 1.42 - - 9.64 20.10 0.01 0.067 5.3 6.0 

CA4 Static Cold Check valve 0.056 1.10 1.45 0.018 0.009 8.84 20.26 0.01 0.041 10.8 10.9 

CA7 Static Cold Check valve 0.058 1.09 1.43 0.018 0.009 8.72 20.22 0.01 0.041 - - 

CB7 Static Cold Check valve 0.052 1.07 1.36 0.018 0.011 8.85 19.12 0.02 0.053 5.9 3.2 

VR Static Spare Pump Volute 0.046 0.50 1.14 0.027 0.017 9.56 20.79 0.04 0.049 9.8 16.2 

MB2 Static Hot Shutoff valve 0.042 0.72 0.51 0.043 0.017 10.77 19.74 0.19 0.073 2.6 1.9 

MA9 Static Hot Shutoff valve 0.052 0.72 0.24 0.041 0.011 10.54 20.78 0.24 0.051 5.1 10.0 

MA1 Static Hot Shutoff valve 0.052 0.72 0.22 0.039 0.013 10.50 20.74 0.24 0.049 5.2 9.5 

PV Static Pump Volute 0.108 1.11 0.89 0.032 0.008 9.30 19.83 0.38 0.027 4.7 13.0 

KRB Static Pump Cover 0.062 0.31 1.17 - - 8.03 22.00 0.17 0.038 27.8 - 

277 Static - 0.052 0.54 1.81 - - 8.13 20.50 0.06 0.019 22.5 28.0 

278 Static - 0.038 0.28 1.00 0.008 0.019 8.27 20.20 0.13 0.030 18.6 15.0 

279 Static - 0.040 0.37 1.36 - - (7.85) 22.00 0.22 0.032 39.5 40.0 

281 Static - 0.036 0.41 0.45 - - 8.60 23.10 0.17 0.053 31.4 30.0 

282 Static - 0.035 0.43 0.35 - - 8.53 22.50 0.15 0.040 29.7 38.0 

283 Static - 0.036 0.48 0.53 - - (7.88) 22.60 0.23 0.032 42.6 42.0 
A-3

Table A1. (Contd.)

Heat Chemical Composition (wt.%)* Ferrite (%)

ID Process Product C Mn Si P S Ni Cr Mo N Calc. Mea

291 Static - 0.065 0.28 1.59 - - 10.60 19.60 0.66 0.054 4.2 6.0 

292 Static - 0.090 0.34 1.57 0.018 0.016 (7.52) 21.60 0.13 0.039 23.9 28.0 

C'5 Centrifugal 0.034 0.62 1.04 - - 9.00 20.70 0.17 0.040 15.57 11.0 

FE Static 0.035 0.80 0.54 0.022 0.012 8.47 21.04 0.08 0.051 17.59 16.5 

FF Static 0.038 0.26 1.16 0.020 0.010 8.33 19.72 0.34 0.026 17.71 12.0 

FC Static 0.042 0.91 1.09 0.027 14.000 8.19 20.73 0.13 0.035 20.93 20.1 

FG Centrifugal 0.040 0.74 1.03 0.024 0.016 8.08 20.65 0.02 0.073 15.30 17.0 

FH Centrifugal 0.050 0.71 1.18 0.032 0.017 8.07 20.70 0.05 0.045 18.34 21.5 

A-F Static Pipe 0.059 0.70 1.07 - - 8.21 19.19 0.13 0.039 9.11 - 

A-G Static Pipe 0.051 0.56 1.20 - - 8.08 20.41 0.12 0.042 17.40 - 

B-G Static Elbow 0.040 0.66 1.51 - - 8.51 20.69 0.25 0.053 18.13 - 

Grade CF-8M with <10% Ni

758 Static Elbow 0.040 0.84 0.69 0.018 - 9.66 19.23 3.12 0.040 20.8 19.2 

205 Centrifugal Pipe 0.040 0.93 0.63 0.019 - (8.80) (17.88) 3.37 0.040 21.0 15.9 

70 Static Slab/Plate 0.066 0.55 0.72 0.021 0.016 9.01 19.17 2.30 0.049 14.2 18.9 

74 Static Slab/Plate 0.064 0.54 0.73 0.022 0.016 9.03 19.11 2.51 0.048 15.5 18.4 

75 Static Slab/Plate 0.065 0.53 0.67 0.022 0.012 9.12 20.86 2.58 0.052 24.8 27.8 

64 Static Keel block 0.038 0.60 0.63 0.006 0.005 9.40 20.76 2.46 0.038 29.0 28.4 

65 Static Keel block 0.049 0.50 0.48 0.012 0.007 9.63 20.78 2.57 0.064 20.9 23.4 

66 Static Keel block 0.047 0.60 0.49 0.012 0.007 9.28 19.45 2.39 0.029 19.6 19.8 

285 Static - 0.047 0.48 0.86 9.49 18.80 2.35 0.039 14.0 10.0 

286 Static - 0.072 0.40 1.33 0.044 0.015 9.13 20.20 2.44 0.062 18.9 22.0 

287 Static - 0.047 0.50 0.51 - - (8.46) 20.50 2.58 0.033 37.2 38.0 

288 Static - 0.052 0.47 1.70 - - (8.40) 19.60 2.53 0.022 35.6 28.0 

289 Static - 0.091 0.48 1.44 - - (8.25) 19.70 2.30 0.032 22.6 30.0 

290 Static - 0.054 0.41 1.51 - - (8.30) 20.00 2.40 0.050 31.3 32.0 

EK Static 50°elbow 0.035 0.89 1.08 - - 9.70 21.10 2.51 0.054 28.0 - 

EK Static Ex. elbow 0.034 0.88 1.05 - - 9.55 21.15 2.51 0.054 30.0 - 

EC Static Sc1 elbow 0.033 0.86 1.01 - - 9.40 21.20 2.51 0.054 32.2 - 

C2375 Centrifugal Pipe 0.050 0.86 0.74 - - 9.46 19.93 2.55 0.040 20.7 21.0 

C1488 Centrifugal Pipe 0.061 1.02 0.53 - - 9.48 20.95 2.63 0.056 22.1 14.0 

B-E Static - 0.070 0.44 1.12 - - 9.20 19.80 2.10 0.027 18.1 - 

B-F Static - 0.050 0.54 1.11 - - 9.10 20.50 2.30 0.021 30.8 - 
A-4

Table A1. (Contd.)

Heat Chemical Composition (wt.%)* Ferrite (%)

ID Process Product C Mn Si P S Ni Cr Mo N Calc. Mea

B-E Static - 0.070 0.44 1.12 - - 9.20 19.80 2.10 0.027 18.1 - 

B-F Static - 0.050 0.54 1.11 - - 9.10 20.50 2.30 0.021 30.8 - 

B-B Centrifugal Pipe 0.053 0.80 0.95 - - 9.52 20.52 2.20 0.045 20.6 - 

A-B Centrifugal Pipe 0.053 0.80 0.95 - - 9.52 20.52 2.20 0.045 20.6 - 

A-C Centrifugal Pipe 0.044 0.62 1.16 - - 9.10 20.60 2.24 0.049 27.2 - 

A-D Centrifugal Pipe 0.059 0.76 0.96 - - 9.28 20.61 2.15 0.049 21.0 - 

A-E Centrifugal Pipe 0.050 0.84 1.30 - - 9.32 20.75 2.30 0.042 26.8 - 

L-Hi - Large Pipe 0.046 0.88 1.26 0.024 0.007 9.26 20.47 2.22 0.032 27.2 - 

L-Lo - Large Pipe 0.050 0.82 0.90 0.025 0.005 9.96 19.58 2.23 0.058 12.0 - 

M-Hi - Med. Pipe 0.046 0.78 1.30 0.024 0.007 9.57 20.88 2.28 0.043 26.0 - 

M-Lo - Med. Pipe 0.050 0.84 0.79 0.025 0.005 9.86 19.29 2.29 0.056 11.5 

Grade CF-8M with ≥10% Ni

P4 Centrifugal Pipe 0.58 m OD 

32-mm wall 0.040 1.07 1.02 0.019 0.016 10.00 19.64 2.05 0.151 5.9 10.0 

62 Static Keel block 0.063 0.72 0.56 0.007 0.005 12.39 18.29 2.57 0.030 2.8 

63 Static Keel block 0.055 0.61 0.58 0.007 0.006 11.85 19.37 2.57 0.031 6.4 10.4 

Rhot Static Hot-leg elbow 0.037 0.77 1.03 0.022 0.008 10.60 20.00 2.09 0.044 13.0 10.3 

Rcrs Static Cold-leg elbow 0.039 0.82 1.11 0.020 0.012 10.50 19.60 2.08 0.037 12.3 9.7 

Y1422 Static 45° connection 0.040 0.80 0.90 - - 10.48 21.94 2.49 0.040 27.1 - 

Y4331 Static - 0.045 0.76 1.16 - - 10.10 20.70 2.59 0.038 - 

Y3296 Static - 0.035 0.67 1.21 - - 10.20 22.20 2.65 0.040 35.8 35.0 

FK Centrifugal - 0.060 1.09 0.75 0.016 0.016 10.45 20.80 2.62 0.056 15.4 14.0 

FL Static - 0.040 0.79 0.81 0.021 0.016 10.56 20.76 2.48 0.042 18.6 19.0 

FB Static - 0.053 0.83 0.93 0.024 0.013 10.56 20.12 2.52 0.042 14.0 17.3 

A Static Plate A 0.036 0.69 1.21 - - 10.30 22.20 2.66 0.043 33.8 - 

B Static Plate B 0.045 0.76 1.16 - - 10.07 20.70 2.59 0.038 23.4 - 

CC Static Plate CC 0.038 0.71 1.20 - - 10.43 22.11 2.75 0.042 32.2 - 

DI Static Plate DI 0.050 0.80 1.17 - - 10.20 20.70 2.58 0.045 20.4 - 

B-A Centrifugal Pipe 0.050 0.90 1.51 - - 10.30 21.30 3.10 0.060 25.7 - 

B-C Centrifugal Pipe 0.048 0.84 0.64 - - 10.46 20.01 2.16 0.051 11.3 - 

A-A Centrifugal Pipe 0.048 0.84 0.64 - - 10.46 20.01 2.16 0.051 11.3 - 

* Values higher than those specified in ASTM A531 Grades CF-3, CF-3M, CF-8, and CF-8M are underlined, and lower values are within 
B-1

APPENDIX B: J-R CURVE CHARACTERIZATION 

The J-R curve tests were performed according to ASTM Specifications E 813-85 (Standard Test 

Method for JIc. a Measure of Fracture Toughness) and E 1152-87 (Standard Test Method for 

Determining J-R Curve). Compact-tension (CT) specimens, 25.4 mm (1 in.) thick with 10% side 

grooves, were used for the tests. The CT specimen design is similar to the specimen of ASTM 

Specification E 399, the notch region is modified in accordance with E 813 and E 5112 to permit 

measurement of load-line displacement by axial extensometer. The extensometer was 

mounted on razor blades that were screwed onto the specimen along the load-line. 

Prior to testing, the specimens were fatigue-precracked at room temperature and at load levels 

within the linear elastic range. The final ratio of the initial crack length to width (a/W) after 

precracking was about 0.55. The final 1-mm (0.04-in.) crack extension was carried out at a load 

range of 13 kN (2.92 kip) to 1.3 kN (0.292 kip), Kmax was <25 MPa·m1/2 (22.6 ksi·in.1/2). After 

precracking, all specimens were side-grooved by 20% of the total specimen thickness (i.e., 10% 

per side), to ensure uniform crack growth during testing. 

The J-R curve tests were performed on an Instron testing machine with 90 kN (20 kip) maximum 

load capacity. The load and 

load-line displacement data were digitized with digital voltmeters and stored on a disk for post 

test analysis and correction of the test data. The single-specimen compliance procedure was 

used to estimate the crack extension. Rotation and modulus corrections were applied to the 

compliance data. Both deformation theory and modified forms of the J integral were evaluated 

for each test. 

After each test, the specimen was heated to 350°C to heat-tint the exposed fracture surface. 

The specimen was then fractured at liquid nitrogen temperature. The initial (i.e., fatigue 

precrack) and final (test) crack lengths were measured optically for both halves of the fractured 

specimen. The crack lengths were determined by the 9/8 averaging technique (i.e., the two 

near-surface measurements were averaged and the resultant value averaged with the 

remaining seven measurements). 

The fracture toughness JIc values were determined in accordance with ASTM Specifications 

E 813-81 and E 813-85. For the former, JIc is defined as the intersection of the blunting line 

given by J = 2σf ∆a, and the linear fit of the J-vs.-∆a test data between the 

0.15-mm and 1.5-mm exclusion lines. The flow stress, σf, is the average of the 0.2% yield 

strength and the ultimate strength. The ASTM Specification E 813-85 procedure defines JIc as 

the intersection of the 0.2-mm offset line with the power-law fit (of the form 

J = C∆an) of the test data between the exclusion lines. J-R curve tests on CASS materials 

indicate that a slope of four times the flow stress (4σf) for the blunting line expresses the J-vs.-

∆a data better than the slope of 2σf that is defined in E 813-81 or E 813-85. The fracture 

toughness JIc values were determined with the 4σf slope for the blunting line and the 0.2-mm 

offset line.

The tearing modulus was also evaluated for each test. The tearing modulus is given by T = 

E(dJ/da)/ σf

2, where E is the Young's modulus and σf is the flow stress. The ASTM E 813-81 

value of tearing modulus is determined from the slope dJ/da of the linear fit to the J-vs.-∆a data. 

For the power law curve fits, an average value of dJ/da was calculatedA27 to obtain average 

tearing modulus. The fracture toughness results obtained at Argonne on several experimental 

and commercial heats of CASS materials aged up to 58,000 h at 290, 320, 350, 400, and 

450°C, (554, 608, 662, 752, and 842°F) and for the service-aged materials from the KBR pump 
B-2

cover plate and the decommissioned Shippingport reactor valve bodies and pump volute and 

impeller,A1–A7 are given in Table B1. Fracture toughness data from studies at EPRI,A13

EdF,A9-12 Framatome,A14,15 several institutions in Japan,A18,19,21,22 Westinghouse,A25,26 and 

TWI,A24 are also included. The actual fracture toughness J-R curve data (J vs. ∆a) for various 

grades and heats of unaged and aged CASS materials are given in Table B2. Note that for a 

few test specimens, the modified-J values are listed instead of deformation-J. These J-R curves 

are identified as Jm vs. ∆a in Table B2, and the rest as Jd vs. ∆a. For these tests, the JIc, 

coefficient C, and exponent n, corresponding to the deformation-J and modified-J values are 

listed in Table B3. The tensile test data for thermally aged CASS materials from the Argonne 

study are presented in NUREG/CR-6142.A6 

Data Analysis Procedure 

The compliance method was used to determine the crack length during the tests. The HudakSaxena calibration equationA28 was used to relate the specimen load-line elastic compliance Ci

on an unloading/loading sequence with the crack length ai. The compliance, i.e., slope (∆δ/∆P) 

of the load-line displacement-vs.-load record obtained during the unloading/loading sequence, is 

given by

, (B-1)

and

 (B-2)

where Ee is the effective elastic modulus, Be is the effective specimen thickness expressed as 

B – (B – BN)2/B, and W is specimen width.

Both rotation and modulus corrections are applied to the compliance data. The modulus 

correction A28 is used to account for the uncertainties in testing, i.e., in the values of initial crack 

length determined by compliance and measured optically. The effective modulus EM is 

determined from

, (B-3)

and

 , (B-4)
B-3

where Co is initial compliance, Be is effective specimen thickness, and ao is the initial physical 

crack size measured optically.

To account for crack-opening displacement in CT specimens, the crack size should be

corrected for rotation.A29 The corrected compliance is calculated from

, (B-5)

and

, (B-6)

where Cc and Cm are the corrected and measured elastic compliance at the load line, H* is the 

initial half span of load points, R is the radius of rotation of the crack centerline [(W + a)/2)], a is 

the updated crack length, D is one-half of the initial distance between the displacement points 

(i.e., half gage length), dm is the total measured load-line displacement, and θ is the angle of 

rotation of a rigid-body element about the unbroken midsection line. 

The J value is calculated at any point on the load-vs.-load-line displacement record by means of 

the relationship

, (B-7)

where Jel is the elastic component of J and Jpl is the plastic component of J. For a CT 

specimen, at a point corresponding to the coordinates Pi and δi on the specimen load-vs.-loadline displacement record, ai is (ao + ∆ai

), and the deformation J is given by

, (B-8)

where, from ASTM method E 399,

, (B-9)

with

 

, (B-10)
B-4

and

, (B-11)

where υ is Poisson's ratio, b is the uncracked ligament, Apl is the plastic component of the area 

under the load-vs.-load-line displacement record, and η is a factor that accounts for the tensile 

component of the load as given by

, (B-12)

and γ a factor that accounts for limited crack growth as given by

, (B-13)

The modified J values (i.e., JM) are calculated from the relationship (Ref. A30) 

, (B-14)

where

, (B-15)

According to ASTM Specification E 1152-87, the JD-R curves are valid only for crack growth up 

to 10% of the initial uncracked ligament. In addition, they show a dependence on specimen 

size. The JM-R curves have been demonstrated to be independent of specimen size and yield 

valid results for larger crack growth.

Data Qualification

The various validity criteria specified in ASTM Specification E 813-85 for JIc and in ASTM 

Specification E 1152-87 for the J-R curve were used to qualify the results from each test. The 

various criteria include maximum values of crack extension and J-integral; limits for initial 

uncracked ligament, effective elastic modulus, optically measured physical crack length, and 

spacing of J-∆a data points. The ω criterionA31 was also used to ensure that a region of J 

dominance exists.

For the present investigation, most of the unaged or short-term-aged specimens yielded invalid 

JIc values because of the relatively high toughness of the material. The reasons for the 

discrepancies are data point spacing, shape of the final crack front, or size of the uncracked 

ligament. In general, the size of the uncracked ligament or the specimen thickness was 

inadequate for the unaged or short-term-aged specimens because of the relatively high 

toughness of the material. The Jmax limit for the J-vs.-∆a data was ignored in most tests to 

obtain a good power-law fit of the test data. 

The shape of the crack front was also very irregular for most CASS materials. This may be 

attributed to the coarse grain structure of the casting and differences in ferrite morphology. 
B-5

CASS materials with large columnar grains, in particular, showed significant variation in crack 

length along the width of a specimen. Furthermore, the crack front always had a leading crack 

near the edges of the specimen. The near-surface measurements of the final physical crack 

length were often >±1.02 mm, the maximum value allowed for data qualification.

The fracture surfaces often showed uncracked ridges or ligaments along the direction of crack 

extension. The uncracked ligaments add significant error to the estimation of crack length by 

compliance. Therefore, the difference between the crack extension predicted from elastic 

compliance and the average measured physical crack extension is more than the maximum 

value allowed by ASTM E 1152. 

All tests showed significant load relaxation during the unloading/reloading cycle for estimating 

crack length by elastic compliance. All unloadings were 25% of the load. The load at the end of 

the unloading/reloading cycle is always lower than it was at the start of the unloading cycle. The 

difference is appreciable for the room-temperature test. Therefore, the initial 20-30% of the 

unloading curve were ignored in estimating crack length. 
B-6

Table B1. The fracture toughness J-R curves, tensile properties and Charpy-impact energy of unaged and aged 

Heat 

ID

Specimen 

ID Process

Calc. 

Ferrite 

(%)

Aging

Temp 

(°C)

Aging 

Time 

(h)

Test 

Temp 

(°C)

Coeff. 

C

Exponent

n Jic 

(kJ/m2)

Yield

Stress 

(MPa)

Ultimate

Stress 

(MPa)

Flow 

Stress 

(MPa)

Elongation 

(%)

Red. 

in 

Area 

(%)

Charpy 

Impact 

Energy 

(J/cm2)

R

CF-3

I I1S-03 S 20.4 - - 25 718.5 0.694 475.9 251.1 571.6 411.3 76.3 76.6 179.7 

I I1S-01 S 20.4 - - 25 861.5 0.591 623.9 251.1 571.6 411.3 76.3 76.6 179.7 

I I2S-01 S 20.4 - - 25 811.6 0.743 478.2 251.1 571.6 411.3 76.3 76.6 179.7 

I I1S-07 S 20.4 320 30000 25 707.5 0.560 453.5 262.9 583.4 423.1 49.7 63.5 214.4 

I I1S-06 S 20.4 350 10000 25 741.1 0.522 497.8 299.8 634.0 466.9 66.3 69.3 141.2 

I I1S-04 S 20.4 350 10000 25 705.8 0.539 455.9 299.8 634.0 466.9 66.3 69.3 141.2 

I I2S-03 S 20.4 350 10000 25 684.2 0.747 330.2 299.8 634.0 466.9 66.3 69.3 141.2 

I I1S-02 S 20.4 - - 290 512.6 0.459 386.1 168.8 399.6 284.2 36.2 63.2 140.7 

I I2S-02 S 20.4 - - 290 536.9 0.561 376.7 168.8 399.6 284.2 36.2 63.2 140.7 

I I1S-08 S 20.4 320 30000 290 394.2 0.494 251.8 171.1 447.9 309.5 25.1 59.7 194.1 

I I1S-05 S 20.4 350 10000 290 385.5 0.480 249.9 186.8 420.6 303.7 36.6 49.1 130.1 

I I2S-04 S 20.4 350 10000 290 425.0 0.512 274.5 186.8 420.6 303.7 36.6 49.1 130.1 

P2 P2B-03 C 12.5 - - 25 1250.6 0.817 1271.7 219.4 569.9 394.7 78.7 73.8 385.8 

P2 P2B-01 C 12.5 - - 25 1250.6 0.890 1300.1 219.4 569.9 394.7 78.7 73.8 385.8 

P2 P2T-01 C 12.5 - - 25 1241.6 0.754 1365.3 219.4 569.9 394.7 78.7 73.8 385.8 

P2 P2T-19 C 12.5 290 58000 25 1542.2 0.897 2272.4 263.6 583.8 423.7 58.3 79.3 424.5 

P2 P2B-16 C 12.5 320 55000 25 1327.2 0.654 1284.5 249.7 605.2 427.5 49.4 78.3 248.7 

P2 P2T-06 C 12.5 350 3000 25 1178.3 0.820 935.4 - - - - - 360.4 

P2 P2T-08 C 12.5 350 10000 25 1221.9 0.897 913.3 255.6 601.5 428.6 75.1 84.2 286.7 

P2 P2T-10 C 12.5 350 10000 25 1426.5 0.728 1468.0 255.6 601.5 428.6 75.1 84.2 286.7 

P2 P2B-11 C 12.5 350 30000 25 960.6 0.643 688.4 240.1 620.3 430.2 67.7 73.2 224.3 

P2 P2B-06 C 12.5 400 10000 25 1053.6 0.765 747.1 - - - - - 209.2 

P2 P2T-04 C 12.5 400 10000 25 1059.3 0.666 820.2 234.9 610.0 422.4 - 73.4 159.5 

P2 P2B-02 C 12.5 - - 290 1080.9 0.691 1483.5 - - - - - 176.7 

P2 P2T-02 C 12.5 - - 290 873.7 0.694 892.3 149.4 396.0 272.7 43.5 65.9 300.5 

P2 P2T-20 C 12.5 290 58000 290 1128.0 0.554 1,314.8 149.4 396.0 272.7 43.5 65.9 300.5 

P2 P2B-17 C 12.5 320 55000 290 1076.4 0.525 1,192.3 170.9 416.7 293.8 35.5 72.3 - 

P2 P2T-07 C 12.5 350 3000 290 980.8 0.689 1060.3 170.0 417.4 293.7 31.4 65.2 - 

P2 P2T-09 C 12.5 350 10000 290 964.9 0.717 1033.8 - - - - - 347.5 

P2 P2B-12 C 12.5 350 30000 290 796.5 0.726 650.7 156.1 414.3 285.2 44.1 70.1 321.6 

P2 P2T-05 C 12.5 400 10000 290 893.1 0.484 874.6 152.8 431.3 292.1 36.1 59.8 344.5 

69 692-08B S 21.0 - - 25 405.4 0.597 204.4 276.1 594.8 435.5 55.6 51.7 207.1 

69 692-08T S 21.0 - - 25 552.0 0.700 267.0 276.1 594.8 435.5 55.6 51.7 207.1 
B-7

Table B1. (Contd.)

Heat 

ID

Specime

n ID Process

Calc. 

Ferrite 

(%)

Aging

Temp 

(°C)

Aging 

Time 

(h)

Test 

Temp 

(°C)

Coeff. 

C

Exponent

n Jic 

(kJ/m2)

Yield

Stress 

(MPa)

Ultimate 

Stress 

(MPa)

Flow 

Stress 

(MPa)

Elongation 

(%)

Red. 

in 

Area 

(%)

Charpy 

Impact 

Energy 

(J/cm2)

R

69 691-06T S 21.0 320 30000 25 834.2 0.586 567.2 277.2 570.7 424.0 31.5 57.6 187.0 

69 691-03B S 21.0 320 50000 25 701.0 0.466 486.0 249.7 605.2 427.5 49.4 78.3 184.4 

69 692-05V S 21.0 320 50000 25 854.0 0.603 557.9 249.7 605.2 427.5 49.4 78.3 184.4 

69 691-04B S 21.0 350 2570 25 888.8 0.425 702.9 294.0 640.8 467.4 65.1 74.3 154.1 

69 691-01T S 21.0 350 10000 25 770.8 0.559 514.0 263.7 631.2 447.4 53.5 74.7 188.6 

69 691-04T S 21.0 350 30000 25 626.2 0.497 406.7 262.8 663.4 463.1 51.6 71.7 120.1 

69 691-03B S 21.0 400 2570 25 64.2 0.368 454.9 277.3 661.0 469.1 48.4 66.5 141.6 

69 696-01T S 21.0 400 10000 25 548.3 0.527 323.1 275.9 681.4 478.7 53.5 67.7 101.5 

69 691-05B S 21.0 450 2570 25 661.4 0.375 495.1 267.2 678.3 472.7 46.6 72.3 121.1 

69 693-07T S 21.0 - - 290 756.3 0.312 700.1 183.9 419.0 301.4 34.8 61.6 257.7 

69 693-01V S 21.0 - - 290 424.8 0.540 266.3 183.9 419.0 301.4 34.8 61.6 257.7 

69 691-07T S 21.0 320 30000 290 492.9 0.410 376.5 170.7 420.0 295.4 23.6 59.1 213.0 

69 691-03T S 21.0 320 50000 290 364.9 0.530 210.8 - - 339.8 - - 176.0 

69 691-06T S 21.0 350 2570 290 523.7 0.259 450.9 173.1 451.3 312.2 32.3 53.8 261.2 

69 691-02T S 21.0 350 10000 290 362.6 0.756 158.4 168.1 421.5 294.8 26.5 60.8 169.3 

69 691-03T S 21.0 350 30000 290 365.5 0.545 210.3 191.9 454.7 323.3 29.4 51.4 159.8 

69 691-05T S 21.0 400 2570 290 368.5 0.412 255.0 163.9 444.8 304.4 21.8 33.2 140.6 

69 697-01T S 21.0 400 10000 290 296.4 0.510 166.8 185.1 488.1 336.6 24.8 48.2 135.0 

69 691-03T S 21.0 450 2570 290 376.0 0.305 261.9 176.7 478.4 327.6 28.0 48.0 123.8 

TWI - S 17.2 - - 300 777.0 0.624 504.0 255.5 585.3 420.4 48.5 - - 

TWI - S 17.2 400 1000 300 508.9 0.736 274.5 244.0 591.0 295.5 50.0 - - 

TWI - S 17.2 400 10000 300 543.4 0.663 297.3 244.3 594.7 297.3 49.3 - - 

CF-3M ≥10%Ni

EL S 33.5 400 3000 320 69.8 0.407 37.7 258.0 670.0 464.0 - - - 

CF-8

68 683-05B S 14.9 - - 25 552.8 0.586 324.4 276.8 523.6 400.2 40.9 51.3 245.4 

68 683-05T S 14.9 - - 25 485.5 0.554 282.3 276.8 523.6 400.2 40.9 51.3 245.4 

68 683-03V S 14.9 - - 25 526.0 0.562 311.8 276.8 523.6 400.2 40.9 51.3 245.4 

68 683-06T S 14.9 Ann. - 25 1170.2 0.529 1,097.4 276.8 523.6 400.2 40.9 51.3 237.4 

68 682-06T S 14.9 320 30000 25 864.1 0.484 647.3 320.0 602.6 461.3 49.8 74.1 135.1 

68 683-02B S 14.9 320 52600 25 860.1 0.568 596.3 308.3 609.2 458.8 49.6 71.2 96.0 

68 682-05V S 14.9 320 52600 25 679.5 0.442 492.3 308.3 609.2 458.8 49.6 71.2 96.0 

68 681-04B S 14.9 350 2570 25 1037.7 0.608 798.0 288.2 600.5 444.3 63.1 74.4 192.9 
B-8

Table B1. (Contd.)

Heat 

ID

Specime

n ID Process

Calc. 

Ferrite 

(%)

Aging

Temp 

(°C)

Aging 

Time 

(h)

Test 

Temp 

(°C)

Coeff. 

C

Exponent

n Jic 

(kJ/m2)

Yield

Stress 

(MPa)

Ultimate 

Stress 

(MPa)

Flow 

Stress 

(MPa)

Elongation 

(%)

Red. 

in 

Area 

(%)

Charpy 

Impact 

Energy 

(J/cm2)

R

68 682-02T S 14.9 350 10000 25 719.1 0.546 475.2 287.2 603.9 445.5 53.1 76.8 100.0 

68 682-04T S 14.9 350 30000 25 430.4 0.634 205.1 289.2 640.0 464.6 48.0 69.8 80.6 

68 681-06V S 14.9 350 30000 25 357.5 0.472 206.0 289.2 640.0 464.6 48.0 69.8 80.6 

68 681-03B S 14.9 400 2570 25 648.6 0.531 408.4 292.0 643.7 467.8 75.0 64.3 74.1 

68 681-01T S 14.9 400 10000 25 487.6 0.578 360.5 306.2 643.3 474.8 39.1 57.2 46.4 

68 681-03V S 14.9 400 10000 25 443.4 0.626 214.0 306.2 643.3 474.8 39.1 57.2 46.4 

68 682-08B S 14.9 400 10000* 25 627.4 0.481 412.7 306.2 643.3 474.8 39.1 57.2 74.7 

68 681-04T S 14.9 450 2570 25 467.7 0.448 294.7 300.4 643.0 471.7 41.5 53.7 54.2 

68 681-05B S 14.9 450 2570 25 532.9 0.680 252.6 300.4 643.0 471.7 41.5 53.7 54.2 

68 C340 S 14.9 350 138000 54 480.2 0.653 - - - - - - - 

68 C341 S 14.9 350 138000 54 487.9 0.547 - - - - - - - 

68 683-07T S 14.9 - - 290 783.0 0.271 753.1 159.6 404.8 282.2 33.6 60.6 287.1 

68 683-06B S 14.9 Ann. - 290 553.1 0.513 413.0 159.6 404.8 282.2 33.6 60.6 220.5 

68 682-07T S 14.9 320 30000 290 401.9 0.601 225.3 172.3 447.6 309.9 37.3 56.6 221.2 

68 683-02T S 14.9 320 52600 290 410.8 0.443 274.0 203.3 479.9 341.6 37.6 52.4 202.4 

68 681-06T S 14.9 350 2570 290 592.8 0.575 406.3 185.1 452.4 318.8 41.7 57.8 147.5 

68 682-03T S 14.9 350 10000 290 451.5 0.544 281.6 166.6 473.8 320.2 28.8 50.9 207.6 

68 682-05T S 14.9 350 30000 290 438.6 0.437 303.8 192.2 464.0 328.1 28.8 49.7 187.7 

68 681-05T S 14.9 400 2570 290 464.9 0.431 335.4 163.1 463.1 313.1 32.1 47.1 139.6 

68 681-02T S 14.9 400 10000 290 396.2 0.510 242.5 185.3 480.0 332.7 31.1 42.4 144.0 

68 681-03T S 14.9 450 2570 290 454.9 0.446 312.2 180.7 495.3 338.0 35.5 39.7 124.8 

C1 C1B-03 S 7.9 - - 25 549.0 0.664 306.3 - - 356.2 - - 59.7 

C1 C1B-01 S 7.9 - - 25 404.6 0.361 291.9 - - 356.2 - - 59.7 

C1 C1B-02 S 7.9 - - 25 416.5 0.724 185.3 - - 356.2 - - 59.7 

C1 C1B-18 S 7.9 320 30000 25 447.5 0.530 270.9 - - 360.0 - - 50.5 

C1 C1B-08 S 7.9 350 10000 25 390.3 0.402 265.9 - - 360.0 - - 63.8 

C1 C1B-11 S 7.9 350 30000 25 451.3 0.620 241.9 - - 365.0 - - 44.6 

C1 C1B-04 S 7.9 - - 290 - - - - - 241.1 - - - 

C1 C1B-05 S 7.9 - - 290 362.4 0.527 236.4 - - 241.4 - - - 

C1 C1B-19 S 7.9 320 30000 290 323.1 0.591 184.8 - - 245.0 - - - 

C1 C1B-09 S 7.9 350 10000 290 357.8 0.619 205.9 - - 245.0 - - - 

C1 C1B-12 S 7.9 350 30000 290 373.8 0.420 273.0 - - 250.0 - - - 

P1 P1B-03 C 17.6 - - 25 866.5 0.652 9,592.2 246.4 583.5 414.9 57.8 67.9 228.3 

P1 P1B-01 C 17.6 - - 25 776.1 0.785 413.3 246.4 583.5 414.9 57.8 67.9 228.3 
B-9

Table B1. (Contd.)

Heat 

ID

Specime

n ID Process

Calc. 

Ferrite 

(%)

Aging

Temp 

(°C)

Aging 

Time 

(h)

Test 

Temp 

(°C)

Coeff. 

C

Exponent

n Jic 

(kJ/m2)

Yield

Stress 

(MPa)

Ultimate 

Stress 

(MPa)

Flow 

Stress 

(MPa)

Elongation 

(%)

Red. 

in 

Area 

(%)

Charpy 

Impact 

Energy 

(J/cm2)

R

P1 P1T-01 C 17.6 - - 25 1017.4 0.958 560.3 246.4 583.5 414.9 57.8 67.9 228.3 

P1 P1T-17 C 17.6 290 58000 25 1058.9 0.784 784.2 264.8 549.0 406.9 65.8 65.1 356.4 

P1 P1B-11 C 17.6 320 30000 25 1105.6 0.429 1,002.3 279.1 596.0 437.5 52.8 76.2 207.3 

P1 P1B-14 C 17.6 320 55000 25 957.9 0.510 723.6 293.3 667.6 480.4 61.1 56.7 144.7 

P1 P1T-08 C 17.6 350 10000 25 526.3 0.808 209.1 275.5 622.6 449.0 77.2 72.6 156.4 

P1 P1B-06 C 17.6 350 10000 25 945.8 0.544 707.3 275.5 622.6 449.0 77.2 72.6 156.4 

P1 P1T-06 C 17.6 350 10000 25 837.6 0.740 468.0 275.5 622.6 449.0 77.2 72.6 156.4 

P1 P1B-09 C 17.6 350 30000 25 708.2 0.644 409.0 271.7 629.6 450.7 53.2 62.4 87.7 

P1 P1B-05 C 17.6 400 10000 25 445.0 0.582 338.7 285.7 668.9 477.3 57.7 56.1 51.7 

P1 P1T-04 C 17.6 400 10000 25 368.0 0.558 186.8 285.7 668.9 477.3 57.7 56.1 51.7 

P1 P1B-02 C 17.6 - - 290 664.1 0.448 554.7 155.1 428.4 291.7 36.1 48.6 255.8 

P1 P1T-02 C 17.6 - - 290 733.8 0.488 630.9 155.1 428.4 291.7 36.1 48.6 255.8 

P1 P1T-18 C 17.6 290 58000 290 579.3 0.760 332.6 173.2 417.0 295.1 37.2 53.4 - 

P1 P1B-12 C 17.6 320 30000 290 571.2 0.403 456.3 175.2 436.9 306.1 27.1 52.4 - 

P1 P1B-15 C 17.6 320 55000 290 615.4 0.527 451.9 194.3 448.4 321.4 35.3 57.5 - 

P1 P1B-07 C 17.6 350 10000 290 529.9 0.424 400.7 178.2 454.4 316.3 42.9 60.7 244.7 

P1 P1T-07 C 17.6 350 10000 290 633.3 0.435 542.1 178.2 454.4 316.3 42.9 60.7 244.7 

P1 P1B-10 C 17.6 350 30000 290 491.5 0.595 294.0 192.9 470.2 331.6 25.1 48.2 - 

P1 P1T-05 C 17.6 400 10000 290 451.7 0.505 293.7 165.1 493.9 329.5 35.6 50.3 133.5 

CA4 CA4-01T S 10.8 264 113900 25 631.8 0.427 476.3 227.5 526.7 377.1 60.6 69.4 145.3 

CA4 CA4-02T S 10.8 400 10000 25 469.9 0.473 301.9 - - - - - 76.1 

CA4 CA4-01B S 10.8 Ann. - 290 475.9 0.698 291.7 - - - - - 225.3 

CA4 CA4-02B S 10.8 264 113900 290 484.0 0.504 361.2 141.8 381.7 261.7 37.6 49.1 179.0 

VR VRI-01 S 9.8 - - 25 884.1 0.510 699.6 273.0 537.0 405.0 54.1 67.3 237.1 

VR VRO-02 S 9.8 400 10000 25 248.9 0.541 122.6 274.3 626.8 450.5 33.2 50.7 72.5 

VR VRO-01 S 9.8 - - 290 457.6 0.477 332.4 159.0 374.0 266.5 32.5 48.0 226.7 

VR VRI-02 S 9.8 400 10000 290 331.6 0.448 213.8 184.7 425.5 305.1 22.4 33.1 105.7 

MA9 MA9-01I S 5.1 <281 113900 25 1504.1 0.367 1,677.1 229.3 490.4 359.8 66.1 78.2 379.4 

MA9 MA9-02O S 5.1 400 10000 25 1117.9 0.326 1,093.5 236.4 508.0 372.2 32.6 65.9 127.6 

MA9 MA9-01O S 5.1 <281 113900 290 1010.6 0.420 1,120.6 159.9 359.5 259.7 31.1 43.9 240.9 

MA9 MA9-02I S 5.1 400 10000 290 668.0 0.277 629.2 144.1 375.2 259.6 36.2 49.2 186.7 

MA1 MA1-01T S 5.2 264 113900 25 1306.4 0.374 1,407.0 230.6 468.8 349.7 30.1 62.2 250.4 

MA1 MA1-01B S 5.2 264 113900 290 745.7 0.429 739.1 132.1 319.9 226.0 24.7 41.7 201.5 
B-10

Table B1. (Contd.)

Heat 

ID

Specime

n ID Process

Calc. 

Ferrite 

(%)

Aging

Temp 

(°C)

Aging 

Time 

(h)

Test 

Temp 

(°C)

Coeff. 

C

Exponent

n Jic 

(kJ/m2)

Yield

Stress 

(MPa)

Ultimate 

Stress 

(MPa)

Flow 

Stress 

(MPa)

Elongation 

(%)

Red. 

in 

Area 

(%)

Charpy 

Impact 

Energy 

(J/cm2)

R

PV PVC-01 S 4.7 Ann. - 25 1422.8 0.350 1,545.7 - - - - - 423.8 

PV PVI-02 S 4.7 264 113900 25 1386.5 0.428 1,508.8 230.1 510.5 370.3 58.1 81.7 306.9 

PV PVO-01 S 4.7 400 10000 25 603.0 0.450 424.6 - - - - - - 

PV PVI-01 S 4.7 Ann. - 290 951.0 0.277 978.6 - - - - - 309.1 

PV PVC-02 S 4.7 264 113900 290 855.7 0.327 857.6 157.4 374.3 265.9 38.5 56.4 257.6 

PV PVO-02 S 4.7 400 10000 290 517.4 0.465 388.4 - - - - - - 

KRB KRB-06R S 27.8 284 68000 25 639.4 0.853 263.4 295.5 559.9 427.7 44.1 65.6 131.1 

KRB KRB-01C S 27.8 284 68000 25 657.1 0.602 396.2 295.5 559.9 427.7 44.1 65.6 131.1 

KRB KRB-04C S 27.8 Ann. - 25 843.9 0.687 531.6 298.1 557.9 428.0 48.3 68.1 232.0 

KRB KRB-05R S 27.8 284 68000 290 764.3 0.346 681.1 200.6 457.5 329.0 34.1 54.5 321.2 

MEA - - - 25 1085.3 0.667 882.5 - - 413.0 - - - 

MEA - - - 25 1383.8 0.504 1,427.1 - - 413.0 - - - 

MEA - - - 25 1401.7 0.475 1,356.8 - - 461.7 - - - 

MEA - - - 25 1220.8 0.555 1,057.1 - - 461.7 - - - 

CF-8M <10%Ni

758 758-02C S 20.8 400 18000 25 209.0 0.591 91.2 - - 501.0 - - 69.6 

758 758-03C S 20.8 400 18000 25 239.1 0.607 103.4 - - 501.0 - - 69.6 

758 758-01C S 20.8 400 18000 290 268.8 4.000 167.2 - - 397.1 - - 118.1 

205 205-25C C 21.0 400 18000 25 493.9 0.555 275.8 - - 451.7 - - 113.8 

205 207-10C C 21.0 - - 290 637.0 0.526 473.9 - - 320.5 - - 271.6 

205 207-09C C 21.0 - - 290 718.8 0.405 615.1 - - 320.5 - - 271.6 

205 205-24C C 21.0 400 18000 290 340.0 0.475 207.2 - - 338.9 - - 116.3 

74 743-05B S 15.5 - - 25 795.4 0.481 610.3 273.3 536.9 405.1 63.0 66.9 210.1 

74 743-05T S 15.5 - - 25 710.6 0.355 577.1 273.3 536.9 405.1 63.0 66.9 210.1 

74 743-03V S 15.5 - - 25 599.0 0.460 418.5 273.3 536.9 405.1 63.0 66.9 210.1 

74 745-03V S 15.5 - - 25 667.9 0.505 464.2 273.3 536.9 405.1 63.0 66.9 210.1 

74 747-03V S 15.5 - - 25 628.3 0.531 403.0 273.3 536.9 405.1 63.0 66.9 210.1 

74 743-03B S 15.5 320 50000 25 532.2 0.452 344.8 304.3 645.9 475.1 45.9 61.4 82.4 

74 744-02V S 15.5 320 50000 25 335.9 0.410 207.8 304.3 645.9 475.1 45.9 61.4 82.4 

74 741-06T S 15.5 350 2570 25 852.6 0.439 692.1 265.0 556.0 410.5 60.7 70.1 159.1 

74 742-05T S 15.5 350 30000 25 391.6 0.548 208.6 266.1 628.5 447.3 44.2 58.5 63.0 
B-11

Table B1. (Contd.)

Heat 

ID

Specimen 

ID Process

Calc. 

Ferrite 

(%)

Aging

Temp 

(°C)

Aging 

Time 

(h)

Test 

Temp 

(°C)

Coeff. 

C

Exponent

n Jic 

(kJ/m2)

Yield

Stress 

(MPa)

Ultimate 

Stress 

(MPa)

Flow 

Stress 

(MPa)

Elongation 

(%)

Red. 

in 

Area 

(%)

Charpy 

Impact 

Energy 

(J/cm2)

R

74 741-03B S 15.5 400 2570 25 556.5 0.420 389.0 268.2 591.0 429.6 42.9 56.7 128.9 

74 741-01T S 15.5 400 10000 25 409.0 0.555 218.7 265.6 619.5 442.5 45.2 70.4 76.5 

74 741-03T S 15.5 450 2570 25 404.0 0.483 238.8 258.3 618.6 438.5 51.2 56.7 84.6 

74 741-05B S 15.5 450 2570 25 502.9 0.548 289.4 258.3 618.6 438.5 51.2 56.7 84.6 

74 743-07T S 15.5 - - 290 452.9 0.562 285.1 168.2 427.6 297.9 30.4 58.7 181.9 

74 743-03T S 15.5 320 52600 290 363.0 0.439 233.2 218.0 488.5 353.3 29.2 42.8 147.4 

74 741-05T S 15.5 400 2570 290 138.2 0.421 309.3 166.2 485.1 325.7 28.5 57.1 135.2 

74 741-02T S 15.5 400 10000 290 348.9 0.546 195.3 178.4 500.6 339.5 32.3 48.8 142.9 

74 741-04T S 15.5 450 3000 290 232.9 0.561 100.7 171.2 493.0 332.1 22.1 40.7 94.4 

75 752-08T S 24.8 - Unaged 25 639.4 0.405 463.2 322.0 600.1 461.1 43.7 71.4 236.9 

75 753-05T S 24.8 - Ann. 25 817.6 0.591 537.4 322.0 600.1 461.1 43.7 71.4 228.3 

75 751-07T S 24.8 290 30000 25 749.3 0.501 515.2 316.0 619.5 467.8 44.6 71.7 266.0 

75 752-06T S 24.8 320 30000 25 493.4 0.509 281.2 358.7 713.5 536.1 41.8 55.7 64.3 

75 753-02B S 24.8 320 50000 25 295.3 0.440 167.7 365.2 726.3 545.7 29.3 40.9 37.3 

75 752-05V S 24.8 320 50000 25 355.8 0.420 214.0 365.2 726.3 545.7 29.3 40.9 37.3 

75 752-02T S 24.8 350 10000 25 478.0 0.496 274.2 346.4 732.8 539.6 41.9 55.9 46.0 

75 752-04T S 24.8 350 30000 25 189.4 0.429 104.3 320.4 741.9 531.1 29.4 36.0 30.5 

75 751-06V S 24.8 350 30000 25 172.2 0.451 90.9 320.4 741.9 531.1 29.4 36.0 30.5 

75 751-03B S 24.8 400 2570 25 407.3 0.461 238.4 339.9 717.6 528.7 36.0 64.2 46.3 

75 751-01B S 24.8 400 10000 25 281.2 0.599 123.8 367.7 747.4 557.6 32.3 45.6 35.8 

75 751-01T S 24.8 400 10000 25 231.4 0.670 88.9 367.7 747.4 557.6 32.3 45.6 35.8 

75 751-03V S 24.8 400 10000 25 309.2 0.548 149.6 367.7 747.4 557.6 32.3 45.6 35.8 

75 753-06B S 24.8 400 10000* 25 277.8 0.334 181.5 367.7 747.4 557.6 32.3 45.6 40.5 

75 751-04T S 24.8 450 2570 25 348.1 0.563 170.4 313.2 733.8 523.5 28.6 40.0 51.1 

75 752-08B S 24.8 - Unage 290 583.3 0.453 436.8 194.2 472.8 333.5 28.3 54.1 164.8 

75 752-03V S 24.8 - Unage 290 600.0 0.347 493.4 194.2 472.8 333.5 28.3 54.1 164.8 

75 753-05B S 24.8 - Ann. 290 518.5 0.562 329.8 194.2 472.8 333.5 28.3 54.1 201.5 

75 752-07T S 24.8 320 30000 290 358.0 0.488 210.0 237.7 562.3 400.0 25.2 46.2 160.0 

75 753-02T S 24.8 320 50000 290 354.5 0.385 234.4 254.2 575.8 415.0 24.1 43.5 124.7 

75 752-03T S 24.8 350 10000 290 288.2 0.627 129.5 214.9 604.9 409.9 28.6 40.1 151.5 
B-12

Table B1. (Contd.)

Heat 

ID

Specimen 

ID Process

Calc. 

Ferrite 

(%)

Aging

Temp 

(°C)

Aging 

Time 

(h)

Test 

Temp 

(°C)

Coeff. 

C

Exponent

n Jic 

(kJ/m2)

Yield

Stress 

(MPa)

Ultimate 

Stress 

(MPa)

Flow 

Stress 

(MPa)

Elongation 

(%)

Red. 

in 

Area 

(%)

Charpy 

Impact 

Energy 

(J/cm2)

R

75 752-05T S 24.8 350 30000 290 262.6 0.669 108.4 233.5 604.8 419.2 24.5 31.4 111.9 

75 751-05T S 24.8 400 2570 290 301.9 0.571 150.2 203.2 591.1 397.2 26.4 41.0 115.5 

75 751-02T S 24.8 400 10000 290 274.2 0.462 156.1 207.5 612.8 410.1 24.5 36.9 135.8 

75 751-02V S 24.8 400 10000 290 363.6 0.320 262.0 207.5 612.8 410.1 24.5 36.9 135.8 

75 751-03T S 24.8 450 2570 290 230.1 0.577 107.1 208.2 602.2 405.2 24.9 28.9 82.0 

EK - S 28.0 350 30000 320 112.3 0.450 - - - - - - - 

EK - S 28.0 325 30000 320 241.7 0.450 - - - - - - - 

L-Hi - C 23.7 - - 325 574.2 0.592 356.0 220.5 501.5 361.0 30.0 - - 

L-Hi - C 23.7 450 13300 325 166.1 0.432 92.0 218.0 592.5 405.3 13.5 - 54.6 

L-Lo - C 11.4 - - 325 522.7 0.803 276.6 147.0 400.5 273.7 38.9 - - 

L-Lo - C 11.4 450 13300 325 329.0 0.578 173.7 161.5 500.5 331.0 24.5 - 143.4 

M-Hi - C 22.7 - - 325 487.4 0.577 300.0 201.0 448.5 324.8 35.0 - - 

M-Hi - C 22.7 450 13300 325 182.0 0.444 100.0 209.5 606.5 408.0 15.8 - 79.6 

CF-8M ≥10%Ni

Y1422 S 27.1 400 980 100 67.4 0.384 38.0 250.0 528.0 389.0 - - 26.0 

Y4331 - S 23.2 400 700 320 217.7 0.665 - - - - - - - 

Y4331 - S 23.2 400 700 320 228.6 0.528 - - - - - - - 

Y4331 - S 23.2 400 700 320 260.7 0.501 - - - - - - - 

Y4331 - S 23.2 400 700 320 283.6 0.857 - - - - - - - 

Y4331 - S 23.2 400 700 320 281.9 0.536 - - - - - - - 

Y4331 - S 23.2 400 700 320 328.6 0.684 - - - - - - - 

Y4331 - S 23.2 400 700 20 105.1 0.513 48.7 324.0 739.0 531.5 20.0 - 26.6 

Y4331 - S 23.2 400 700 100 97.6 0.418 - - - 

Y4331 - S 23.2 400 10000 20 74.1 0.366 42.7 333.0 672.0 502.5 11.0 - 17.5 

Y4331 - S 23.2 400 10000 100 109.4 0.520 - - - 

Y4331 - S 23.2 400 10000 320 123.3 0.541 56.4 225.0 565.0 395.0 - - - 

Y3296 - S 35.8 400 1000 320 91.3 0.478 44.6 276.0 679.0 477.5 - - - 

Y3296 - S 35.8 400 1000 320 112.4 0.342 68.6 276.0 679.0 477.5 - - - 

Y3296 - S 35.8 400 1000 320 88.6 0.541 39.1 276.0 679.0 477.5 - - - 

Y3296 - S 35.8 400 1000 320 82.7 0.333 50.4 276.0 679.0 477.5 - - - 

Y3296 - S 35.8 400 1000 320 72.5 0.457 36.2 276.0 679.0 477.5 - - - 
B-13

Table B1. (Contd.)

Heat 

ID

Specimen 

ID Process

Calc. 

Ferrite 

(%)

Aging

Temp 

(°C)

Aging 

Time 

(h)

Test 

Temp 

(°C)

Coeff. 

C

Exponent

n Jic 

(kJ/m2)

Yield

Stress 

(MPa)

Ultimate 

Stress 

(MPa)

Flow 

Stress 

(MPa)

Elongation 

(%)

Red. 

in 

Area 

(%)

Charpy 

Impact 

Energy 

(J/cm2)

R

Y3296 - S 35.8 400 1000 320 55.4 0.553 23.5 276.0 679.0 477.5 - - - 

Y3296 - S 35.8 400 1000 20 50.2 0.334 30.0 381.0 649.0 515.0 3.6 - 10.5 

Y3296 - S 35.8 400 1000 20 30.9 0.369 17.3 381.0 649.0 515.0 - - 10.5 

Y3296 - S 35.8 400 1000 100 37.0 0.290 - - - - - - - 

FK - C 15.4 - - 25 742.6 0.635 481.9 400.6 - 200.3 - - - 

FK - C 15.4 427 3000 25 383.2 0.441 304.0 510.8 - 255.4 - - 48.5 

FL - S 18.6 400 7500 25 179.8 0.431 108.0 539.8 - 269.9 - - 30.4 

FL - S 18.6 400 7500 200 276.8 0.407 156.7 473.0 - 236.5 - - - 

FL - S 18.6 400 7500 320 240.2 0.244 159.5 427.5 - 213.8 - - - 

CC - S 32.2 400 1000 320 76.1 0.589 30.9 276.0 679.0 477.5 - - - 

DI - S 20.4 400 10000 320 110.8 0.500 53.6 225.0 565.0 395.0 - - - 

DI - S 20.4 400 700 320 243.3 0.530 - - - - - - - 

A-A - C 11.3 - - 25 1698.0 0.606 2,311.0 249.9 539.9 394.9 - - 384.7 

A-A - C 11.3 400 30 25 250.0 540.5 395.2 - - 312.1 

A-A - C 11.3 400 3000 25 257.4 595.4 426.4 - - 127.4 

A-A - C 11.3 400 10000 25 507.8 0.679 242.7 250.3 634.3 442.3 - - 109.4 

A-A - C 11.3 400 20000 25 496.7 0.533 287.5 276.7 630.7 453.7 - - 83.0 

A-A - C 11.3 400 40000 25 625.0 0.450 427.3 281.5 649.5 465.5 - - 83.5 

A-A - C 11.3 - - 325 573.7 0.873 270.4 165.9 441.9 303.9 - - 363.5 

A-A - C 11.3 400 30 325 1097.8 0.688 1,248.9 160.0 460.7 310.3 - - 395.6 

A-A - C 11.3 400 3000 325 155.4 479.4 317.4 - - 261.1 

A-A - C 11.3 400 10000 325 493.7 0.619 291.4 150.3 492.3 321.3 - - 166.5 

A-A - C 11.3 400 20000 325 514.1 0.513 345.3 158.7 504.7 331.7 - - 158.6 

A-A - C 11.3 400 40000 325 632.1 0.430 498.0 163.5 501.5 332.5 - - 159.1 

B-C - C 11.3 - - 25 1725.7 0.663 - - - - - - - 

B-C - C 11.3 400 2211 25 797.6 0.744 - - - - - - - 

B-C - C 11.3 400 28028 25 450.2 0.485 - - - - - - - 

B-C - C 11.3 - - 316 1228.3 0.826 - 145.9 414.6 280.2 - - 317.4 

B-C - C 11.3 400 2211 316 720.4 0.490 601.2 162.9 448.9 305.9 - - 257.8 

B-C - C 11.3 400 28028 316 509.9 0.510 349.2 144.9 487.7 316.3 - - 146.3 
B-14

Table B2. Fracture Toughness J-R Curve data for unaged and aged CASS Materials.

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm

CF-3 Materials

I1S-03 25°C I1S-01 25°C I2S-01 25°C I1S-07 25°C I1S-06 25°C I1S-04 25°C I2S-03 25°C I1S-0

- - - - - - 320°C 30000 h 350°C 10000 h 350°C 10000 h 350°C 10000 h 350°

0.049 33.3 0.053 83.2 0.135 136.5 0.023 12.4 0.062 53.5 0.105 59.7 0.120 113.1 0.102 

0.111 89.9 0.199 149.8 0.062 179.8 0.086 58.2 0.104 137.0 0.195 72.7 0.151 169.8 0.086 

0.043 136.5 0.252 216.4 0.105 233.0 0.148 95.3 0.119 193.9 0.159 216.6 0.206 293.3 0.000 

0.061 209.7 0.299 352.9 0.153 296.3 -0.053 138.2 0.200 274.1 0.350 239.2 0.295 383.1 0.118 

0.139 273.0 0.431 412.8 0.361 532.6 0.130 178.5 0.231 324.2 0.314 342.9 0.400 439.5 0.000 

0.251 342.9 0.523 492.7 0.585 629.2 0.104 201.0 0.308 367.6 0.404 382.7 0.590 522.3 0.130 

0.294 416.1 0.644 569.2 0.788 805.6 0.220 245.6 0.315 431.2 0.513 459.1 0.738 598.5 0.104 

0.435 486.0 0.653 645.8 0.978 885.5 0.315 338.9 0.432 474.6 0.629 538.8 0.878 688.2 0.220 

0.600 555.9 0.789 719.0 1.079 988.7 0.409 385.8 0.513 531.3 0.847 624.8 1.096 794.2 0.227 

0.619 595.9 0.847 802.3 1.339 1,126.6 0.371 436.3 0.660 618.2 0.975 704.5 1.528 899.4 0.258 

0.829 659.1 1.002 915.4 1.810 1,264.2 0.581 523.2 0.869 705.0 1.170 817.3 1.701 1,022.4 0.35

0.916 755.7 1.230 1,018.6 2.081 1,405.0 0.762 601.9 1.056 788.4 1.535 956.2 2.253 1,138.7 0.318 

1.163 892.1 1.517 1,128.5 2.369 1,556.0 0.856 700.1 1.325 882.8 1.901 1,113.4 2.561 1,257.6 0.382 

1.362 1,025.3 1.726 1,238.3 2.711 1,728.7 1.145 791.9 1.614 998.3 2.331 1,296.8 3.107 1,402.2 0.58

1.576 1,160.2 1.749 1,381.5 3.233 1,903.2 1.362 856.4 1.875 1,123.9 3.089 1,467.3 3.714 1,536.7 0.656 

1.927 1,326.3 1.896 1,391.5 3.903 2,071.1 1.612 921.4 2.494 1,239.0 3.759 1,638.2 4.066 1,689.9 0.762 

2.237 1,510.7 2.221 1,544.6 4.386 2,240.5 1.738 956.0 2.757 1,357.9 4.327 1,822.1 4.661 1,820.9 0.839 

2.576 1,742.1 2.265 1,534.6 4.674 2,416.6 2.070 1,035.4 3.099 1,508.6 4.806 2,026.8 5.257 2,005.3 0.856 

3.216 1,980.3 2.831 1,698.6 5.071 2,555.2 2.373 1,115.3 3.639 1,659.0 5.591 2,257.1 5.736 2,163.3 1.213 

4.029 2,205.2 3.368 1,876.5 5.718 2,791.9 2.610 1,200.5 4.390 1,840.0 5.983 2,415.5 6.781 2,379.3 1.392 

4.183 2,213.6 3.793 2,045.9 6.350 3,028.7 2.982 1,272.1 5.120 2,021.0 6.186 2,434.7 7.928 2,628.3 1.512 

4.998 2,413.4 4.638 2,332.8 7.189 3,238.6 3.373 1,387.1 6.011 2,188.4 7.101 2,677.8 9.206 2,870.1 1.738 

5.439 2,589.2 5.498 2,636.5 7.850 3,461.9 3.664 1,413.2 6.784 2,389.6 8.132 2,940.4 10.034 3,073.5 1.954 

6.586 2,866.9 6.218 2,907.1 8.409 3,664.8 4.032 1,523.5 6.974 2,409.6 8.785 3,171.2 10.266 3,099.3 2.070 

7.528 3,130.9 6.321 2,913.9 9.159 3,881.4 4.169 1,561.4 8.040 2,576.9 8.959 3,210.5 11.021 3,276.4 2.337 

8.381 3,394.9 7.704 3,198.6 9.939 4,057.5 4.457 1,581.5 8.682 2,798.4 9.787 3,407.3 11.864 3,446.5 2.485 

9.101 3,604.7 8.660 3,523.3 10.807 4,213.5 4.800 1,642.3 9.295 2,972.8 10.760 3,670.1 12.038 3,479.2 2.610 

9.307 3,645.4 9.704 3,814.4 11.557 4,389.6 4.952 1,670.8 9.544 2,999.5 10.920 3,682.9 12.778 3,609.7 2.982 

10.102 3,828.3 11.013 4,139.5 12.308 4,552.2 5.080 1,705.0 10.216 3,140.2 11.805 3,899.4 12.924 3,629.2 3.373 

10.778 4,051.5 12.131 4,417.1 13.117 4,694.7 5.390 1,716.8 10.930 3,395.3 11.907 3,912.4 3.664 

11.984 4,322.5 12.264 4,471.2 14.279 4,790.2 5.730 1,721.9 11.909 3,616.5 12.924 4,101.9 4.027 

13.014 4,519.1 5.908 1,743.1 12.668 3,811.0 13.040 4,121.4 4.169 

13.191 4,526.0 6.021 1,775.6 12.799 3,831.1 4.489 

6.247 1,818.5 4.952 

6.441 1,843.4 5.390 

5.908 

6.44
B-15

Table B2. (Contd.) 

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm

I1S-02 290°C I1S-08 290°C I1S-05 290°C I2S-04 290°C P2B-03 25°C P2B-01 25°C P2T-01 25°C P2T-1

- - 320°C 30000 h 350°C 10000 h 350°C 10000 h - - - - - - 290°

0.049 36.9 0.018 15.2 0.073 60.4 0.043 20.1 0.231 185.3 0.108 97.1 0.108 97.1 0.046 

0.160 204.7 -0.001 42.5 0.116 104.0 0.105 62.1 0.468 652.9 0.522 670.6 0.522 670.6 0.139 

0.272 298.5 0.042 73.1 0.221 151.0 0.147 110.7 0.784 776.5 0.652 917.6 0.652 917.6 0.138 

0.488 375.4 0.040 111.7 0.279 203.0 0.154 154.4 0.868 917.6 0.783 1,023.5 0.783 1,023.5 0.178 

0.650 445.6 0.301 151.6 0.481 250.0 0.126 194.6 0.937 1,094.1 1.005 1,288.2 1.005 1,288.2 0.226 

0.973 505.4 0.221 194.3 0.504 305.4 0.145 209.7 1.083 1,270.6 1.166 1,500.0 1.166 1,500.0 0.319 

1.150 585.7 0.435 237.0 0.785 360.7 0.336 258.4 1.283 1,447.1 1.381 1,738.2 1.381 1,738.2 0.285 

1.296 666.1 0.487 281.9 1.218 439.6 0.539 315.4 1.560 1,694.1 1.635 1,976.5 1.635 1,976.5 0.266 

1.654 766.2 0.704 325.3 1.591 512.4 0.699 370.8 1.690 1,941.2 1.989 2,320.6 1.989 2,320.6 0.297 

2.253 872.4 0.659 366.6 1.992 588.6 0.991 426.2 1.990 2,170.6 2.381 2,761.8 2.381 2,761.8 0.394 

2.836 973.2 1.067 401.0 2.464 668.9 1.194 488.3 2.321 2,452.9 1.564 2,152.9 0.512 

3.371 1,065.5 1.183 438.2 2.849 746.0 1.433 553.4 2.513 2,708.8 1.888 2,408.8 0.496 

3.890 1,183.1 1.545 472.1 3.287 826.4 1.737 614.5 2.827 3,097.1 2.010 2,682.4 0.59

4.401 1,305.8 1.711 508.7 3.973 902.5 2.003 649.6 3.104 3,441.2 2.341 2,973.5 0.547 

5.225 1,422.1 2.002 542.5 4.502 979.3 2.411 730.0 3.158 3,317.6 2.679 3,247.1 0.570 

6.206 1,538.0 2.000 583.8 5.039 1,052.8 2.860 812.0 3.488 3,785.3 2.894 3,547.1 0.656 

2.401 614.4 5.038 1,086.2 3.324 892.4 3.850 4,138.2 3.295 3,802.9 0.844 

2.474 653.2 5.808 1,136.4 3.818 983.7 4.358 4,500.0 3.710 4,111.8 0.604 

2.774 684.6 6.606 1,233.3 5.022 1,129.7 4.820 4,879.4 3.910 4,402.9 0.857 

3.199 716.3 7.258 1,323.5 5.124 1,139.7 5.452 5,223.5 4.225 4,702.9 0.814 

3.354 757.5 7.998 1,417.1 5.908 1,219.9 6.000 5,417.6 4.734 5,002.9 0.893 

3.676 792.9 8.897 1,534.1 7.084 1,326.9 6.269 5,647.1 5.026 5,294.1 1.092 

3.944 828.2 9.014 1,544.1 7.808 1,443.9 6.330 5,797.1 5.519 5,602.9 1.153 

4.391 860.7 10.088 1,647.7 8.882 1,574.2 6.570 5,858.8 6.012 5,885.3 1.16

4.808 903.6 10.233 1,661.1 10.043 1,714.6 6.878 5,973.5 6.212 6,141.2 1.25

5.510 926.0 11.321 1,781.4 11.174 1,851.6 6.917 6,008.8 6.289 6,167.6 1.253 

5.923 963.5 12.366 1,905.1 11.305 1,861.6 0.231 185.3 6.413 6,202.9 1.42

6.423 1005.5 12.438 1,915.1 12.597 1,985.3 1.607 

6.878 1047.2 12.728 1,995.3 1.652 

7.717 1052.3 1.77

8.211 1077.2 1.807 

8.794 1093.2 1.878 

9.379 1102.5 1.987 

9.906 1112.3 2.167 
B-16

Table B2. (Contd.) 

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm

P2T-06 25°C P2B-07 25°C P2T-08 25°C P2T-10 25°C P2B-11 25°C P2B-06 25°C P2T-04 25°C P2T-0

350°C 3000 h 350°C 3000 h 350°C 10000 h 350°C 10000 h 350°C 30000 h 400°C 10000 h 400°C 10000 h - 

0.154 96.5 0.200 193.2 0.133 105.8 0.097 176.5 0.000 44.2 0.163 232.2 0.095 107.7 0.20

0.446 676.7 0.362 377.6 0.242 450.1 0.460 485.3 0.033 124.4 0.292 406.3 0.238 240.3 0.47

0.654 922.6 0.485 527.0 0.253 679.7 0.642 767.7 0.088 145.5 0.360 539.0 0.333 381.3 0.634 

0.992 1,291.5 0.793 895.9 0.616 1,032.7 0.653 909.0 0.113 156.1 0.448 663.4 0.421 472.4 0.82

1.277 1,642.9 0.962 1,018.8 0.834 1,270.9 0.835 997.2 0.186 179.7 0.659 812.4 0.599 455.4 1.06

1.570 1,959.1 0.977 1,141.9 1.004 1,535.7 0.871 1,129.6 0.117 218.9 0.741 629.5 0.789 612.7 1.353 

1.978 2,363.1 1.162 1,247.2 1.137 1,500.3 1.004 1,288.5 0.311 242.9 0.925 786.8 0.993 795.0 1.60

2.193 2,573.8 1.185 1,511.1 1.330 2,003.5 1.040 1,403.2 0.354 304.0 1.251 1,085.1 1.211 968.9 1.99

2.548 2,793.1 1.332 1,484.4 1.621 2,197.5 1.258 1,659.1 0.172 357.0 1.551 1,283.7 1.442 1,151.0 2.368 

2.956 3,056.2 1.431 1,660.2 2.373 2,700.3 1.404 1,800.3 0.391 438.2 1.728 1,482.6 1.762 1,357.9 2.71

2.987 3,161.7 1.632 1,818.2 2.505 3,071.1 1.621 2,232.8 0.312 499.9 2.082 1,681.1 2.048 1,523.4 2.80

3.134 3,223.0 1.670 1,967.7 2.578 3,230.0 1.924 2,471.0 0.486 525.7 2.173 1,808.3 2.219 1,744.2 3.235 

3.226 3,328.4 1.770 2,152.3 2.760 3,256.3 2.094 2,470.9 0.503 554.5 2.743 1,987.4 2.651 1,931.7 3.622 

3.311 3,425.0 1.847 2,319.4 2.929 3,424.0 2.288 2,682.7 0.547 583.5 2.912 2,135.9 3.077 2,127.8 

3.395 3,433.7 1.977 2,503.9 3.269 3,591.5 2.591 2,894.4 0.484 615.8 3.049 2,205.4 3.408 2,268.5 

2.154 2,661.9 3.572 3,829.7 2.675 3,229.9 0.440 648.9 3.303 2,307.5 3.696 2,409.3 

2.046 2,838.2 4.081 4,094.2 2.942 3,114.9 0.631 677.4 3.478 2,418.4 3.935 2,554.6 

2.177 3,022.7 4.652 4,358.7 3.331 3,335.4 0.575 707.8 3.825 2,574.0 4.577 2,763.1 

2.269 3,031.3 5.307 4,640.8 3.597 3,564.8 0.501 743.5 4.017 2,695.9 5.049 2,950.2 

2.238 3,198.6 5.937 4,922.9 4.191 3,873.4 0.616 778.3 4.380 2,862.6 5.823 3,223.0 

2.423 3,383.0 6.386 5,196.4 4.470 4,164.6 0.653 803.4 4.915 3,088.3 6.541 3,504.2 

2.438 3,567.8 7.102 5,478.4 5.076 4,437.9 0.671 857.2 5.580 3,292.0 7.711 3,994.9

2.676 3,743.3 7.988 5,813.3 5.950 4,799.3 0.877 947.9 6.038 3,501.4 8.542 4,365.0

2.792 3,769.4 8.521 6,095.5 6.799 5,160.7 1.040 980.2 6.587 3,765.5 9.503 4,779.0

2.815 3,927.8 8.606 6,157.3 7.600 5,486.9 1.149 1009.8 7.638 4,030.6 10.683 5,192.4

2.984 4,121.0 8.559 5,830.6 1.087 1052.9 8.498 4,241.0 11.674 5,508.7

3.231 4,314.1 9.433 6,041.9 1.235 1122.9 9.270 4,566.8 11.834 5,552.6

3.354 4,322.6 9.615 6,112.4 1.387 1242.0 9.867 4,848.9

3.601 4,506.9 1.420 1282.1 10.858 5,103.2

3.747 4,709.0 1.737 1303.2 11.237 5,314.9

4.086 4,910.7 1.760 1341.8 11.353 5,367.8

4.209 5,121.6 1.906 1375.5

4.279 5,112.7 1.726 1433.3

4.664 5,358.3 1.952 1499.6

5.173 5,638.8 2.305 1518.2

5.311 5,937.7 2.111 1625.1

5.835 6,174.2 2.575 1709.1

6.089 6,499.2
B-17

Table B2. (Contd.) 

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm

P2T-20 290°C P2B-17 290°C P2T-07 290°C P2T-09 290°C P2B-12 290°C P2T-05 290°C 692-08B 25°C 692-08

290°C 58000 h 320°C 55000 h 350°C 3000 h 350°C 10000 h 350°C 30000 h 400°C 10000 h - - - 

0.010 36.7 0.000 39.4 0.097 79.6 0.087 79.7 0.020 24.0 0.299 320.9 0.063 55.7 0.122 

0.000 62.4 0.000 97.6 0.127 186.1 0.251 139.2 0.059 62.9 0.340 381.8 0.110 38.4 0.22

0.000 118.8 0.000 128.4 0.264 325.5 0.289 325.5 0.047 119.0 0.421 486.9 0.125 72.3 0.334 

0.142 147.4 0.035 160.4 0.244 372.2 0.317 518.5 0.122 151.3 0.482 553.3 0.200 136.4 0.44

0.000 180.4 0.000 194.5 0.381 431.6 0.471 711.2 0.085 186.7 0.571 630.8 0.322 220.5 0.58

0.201 210.0 0.153 229.5 0.566 564.1 0.732 803.7 0.198 221.7 0.788 735.8 0.381 205.0 0.61

0.015 244.5 0.051 272.4 0.449 544.6 0.800 916.7 0.302 257.9 0.842 796.7 0.441 245.4 0.634 

0.000 280.2 0.175 315.6 0.712 716.7 1.052 969.3 0.412 293.5 0.972 890.7 0.524 292.4 0.75

0.177 312.7 0.179 360.6 0.810 809.6 1.109 1,049.0 0.278 335.2 1.074 951.5 0.524 292.4 0.974 

0.067 350.1 0.243 406.2 0.859 896.0 1.099 1,155.6 0.565 370.6 1.094 995.8 0.783 338.6 1.06

0.399 381.5 0.190 455.5 1.083 988.3 1.186 1,261.8 0.502 412.2 1.302 995.4 0.890 383.9 1.27

0.055 425.4 0.291 502.3 1.190 1,247.8 1.302 1,254.9 0.647 451.8 1.480 1,104.0 1.062 427.1 1.592 

0.201 500.8 0.194 555.1 1.326 1,220.5 1.592 1,387.3 0.595 495.7 1.711 1,250.1 1.354 496.8 2.00

0.435 535.6 0.612 594.0 1.473 1,346.5 1.843 1,586.3 0.578 540.8 2.155 1,404.7 1.660 581.8 2.258 

0.412 576.5 0.455 649.0 1.609 1,472.5 2.133 1,791.9 0.599 586.2 2.567 1,550.4 1.700 576.7 2.54

0.512 615.4 0.527 700.9 1.463 1,446.5 2.462 1,984.1 0.806 625.0 3.021 1,699.4 1.916 643.4 3.06

0.411 661.5 0.492 756.0 1.824 1,624.9 2.838 2,262.8 0.826 669.2 3.625 1,908.4 2.376 747.3 3.582 

0.240 711.0 0.889 794.6 2.087 1,777.0 3.535 2,520.6 0.997 709.7 4.203 2,098.4 2.612 785.9 3.508 

0.601 741.5 0.668 857.6 2.243 1,902.9 4.116 2,785.3 0.914 760.4 5.281 2,348.9 3.057 876.4 4.244 

0.568 785.3 0.842 907.7 2.437 1,915.3 4.997 3,056.0 1.034 804.0 5.910 2,604.4 3.903 1,029.0 4.362 

0.656 826.7 0.834 965.0 2.593 2,054.6 5.577 3,327.4 1.091 857.7 5.956 2,614.3 4.551 1,142.2 4.95

0.568 876.5 1.039 1011.7 2.690 2,060.8 6.458 3,571.4 1.062 917.4 6.967 2,829.6 5.316 1,251.2 5.804 

0.826 910.2 1.037 1070.2 2.992 2,239.4 7.019 3,849.5 1.146 981.3 7.699 3,065.8 6.081 1,360.3 6.59

0.671 964.1 1.170 1122.0 3.333 2,457.8 7.978 4,080.0 1.361 1053.5 7.818 3,079.0 6.184 1,352.3 7.393 

0.677 1011.9 1.193 1179.9 3.694 2,669.5 8.394 4,258.6 1.657 1137.4 8.618 3,252.5 6.978 1,465.3 8.188 

0.882 1047.8 1.149 1244.2 4.200 2,907.1 8.539 4,298.2 1.682 1239.0 8.767 3,285.8 7.670 1,590.2 9.013 

0.704 1105.4 1.211 1301.8 4.764 3,124.5 8.656 4,324.5 2.012 1320.5 9.568 3,486.5 8.582 1,703.1 9.99

1.058 1134.2 1.519 1339.2 5.387 3,308.2 2.242 1408.7 10.369 3,673.5 9.744 1,835.2 10.95

0.912 1189.4 1.571 1395.2 5.864 3,526.0 2.609 1484.0 11.066 3,854.2 11.170 1,947.4 12.19

1.255 1216.8 1.708 1446.5 6.331 3,717.2 2.613 1590.2 11.244 3,887.5 12.346 2,059.9 13.35

1.064 1278.1 1.825 1499.5 6.429 3,743.4 3.074 1654.3 11.808 4,007.5 13.655 2,148.6 

1.258 1365.6 2.041 1613.3 7.100 3,900.2 3.377 1729.2 11.926 4,027.5 

1.407 1456.6 2.445 1137.2 7.168 3,919.9 3.575 1815.9 

1.633 1487.3 2.786 1790.6 7.771 4,077.1 3.924 1902.1 

1.738 1529.2 3.024 1943.3 7.878 4,096.6 4.375 1969.4 

1.818 1574.6 3.390 1989.4 8.219 4,235.0 4.835 2047.3 

1.894 1570.1 3.721 2036.2 8.325 4,227.9 

8.394 4,280.9 
B-18

Table B2. (Contd.) 

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm

691-03B 25°C 692-05V 25°C 691-04B 25°C 691-01T 25°C 691-04T 25°C 691-03B 25°C 696-01T 25°C 691-05

320°C 50000 h 320°C 50000 h 350°C 2570 h 350°C 10000 h 350°C 30000 h 400°C 2570 h 400°C 10000 h 450°

0.000 61.4 0.000 58.2 0.032 28.1 0.014 44.64 0.000 23.4 0.070 31.9 0.001 39.87 0.03

0.119 108.7 0.075 102.6 0.127 33.4 0.003 85.71 0.000 69.7 0.114 53.8 0.077 54.72 0.04

0.085 159.5 0.140 150.5 0.083 92.9 0.106 138.86 0.058 103.9 0.082 53.7 0.010 85.91 0.10

0.134 215.0 0.115 201.6 0.004 127.1 0.143 173.51 0.000 145.1 0.055 95.7 0.000 103.82 0.00

0.221 270.3 0.250 254.0 -0.004 180.8 0.000 230.08 0.233 188.6 0.068 191.3 0.377 313.67 0.07

0.280 388.5 0.262 308.9 0.020 251.3 0.065 282.53 0.218 233.8 0.065 206.4 0.000 334.57 0.05

0.396 447.5 0.373 364.6 0.135 242.4 0.284 322.75 0.264 281.1 0.160 142.7 0.455 352.84 0.05

0.524 506.8 0.321 423.8 0.056 290.7 0.151 364.05 0.258 329.6 0.174 243.4 0.513 374.95 0.09

0.672 566.7 0.392 481.4 0.167 349.6 0.406 456.41 0.476 378.3 0.082 310.4 0.539 394.99 0.068 

0.775 626.5 0.474 540.1 0.095 400.7 0.560 507.03 0.430 427.6 0.161 300.4 0.580 414.8 0.082 

0.825 689.8 0.644 658.8 0.266 467.8 0.543 561.78 0.565 478.0 0.255 369.3 0.728 433.48 0.17

1.026 725.6 0.836 777.4 0.262 524.3 0.689 608.51 0.610 529.5 0.357 441.5 0.662 455.31 0.333 

1.179 773.2 0.980 836.5 0.440 577.2 0.797 711.33 0.796 577.4 0.615 544.0 0.707 479.14 0.50

1.479 814.9 1.022 899.5 0.416 642.3 1.026 758.96 1.000 625.0 0.656 545.7 0.851 497.41 0.634 

1.723 889.6 1.165 958.9 0.551 701.1 0.966 814.56 1.133 673.3 0.730 527.3 0.835 519.27 0.888 

1.908 923.0 1.283 1019.1 0.686 762.6 1.070 867.07 1.409 729.3 0.929 604.5 0.000 541.74 1.13

2.115 954.7 1.413 1076.8 0.777 827.2 1.317 911.52 1.620 785.1 1.181 673.5 1.069 565.91 1.405 

2.313 1029.6 1.620 1119.4 0.959 897.1 1.371 962.18 1.833 842.1 1.475 747.5 1.211 588.09 1.832 

2.580 1069.6 1.739 1167.2 1.114 969.9 1.860 1046.2 2.103 896.1 1.720 825.1 1.231 617.47 2.33

2.755 1111.7 1.826 1215.9 1.410 1,070.1 1.950 1096.1 2.946 967.8 2.013 896.6 1.394 636.43 2.794 

3.016 1159.2 2.161 1248.6 1.624 1,163.0 2.235 1135.6 3.302 1015.7 2.248 943.0 1.469 663.27 2.804 

3.296 1208.2 2.249 1306.1 1.909 1,252.9 2.573 1223.6 3.710 1074.5 2.566 1,015.2 1.553 689.09 3.324 

3.557 1258.3 2.431 1358.9 2.259 1,393.5 2.834 1313.0 4.237 1142.4 2.850 1,104.2 1.630 716.02 3.265 

3.934 1303.4 2.745 1402.0 2.327 1,379.1 3.241 1348.6 4.837 1199.0 3.651 1,286.4 1.741 740.19 4.00

4.307 1355.7 3.054 1504.4 2.765 1,509.6 3.625 1380.6 5.507 1264.7 4.226 1,416.8 1.897 761.68 4.32

4.814 1392.9 3.477 1552.5 3.180 1,644.4 4.175 1460.2 6.070 1332.4 4.683 1,551.7 1.963 800.38 4.472 

5.094 1446.2 3.799 1605.3 3.272 1,630.0 4.534 1509.5 6.895 1385.4 5.301 1,695.7 2.267 824.17 5.09

5.603 1480.6 4.217 1651.9 3.843 1,796.9 5.119 1617.6 7.688 1427.3 5.802 1,853.1 2.514 851.84 6.033 

5.911 1520.8 4.507 1698.2 4.238 1,870.1 5.616 1648.0 8.486 1476.6 7.040 2,042.0 2.877 913.99 6.88

6.269 1558.7 4.823 1745.7 5.243 2,129.5 6.396 1716.1 9.253 1525.1 8.027 2,239.9 3.158 973.22 7.785 

7.127 1628.8 5.555 1864.4 5.974 2,293.1 6.937 1746.4 9.863 1583.9 8.101 2,230.9 3.543 996.64 8.698 

7.590 1663.1 5.957 1912.2 7.093 2,512.9 7.742 1734.1 10.512 1655.1 9.325 2,388.3 3.787 1027.7 8.81

8.040 1692.3 6.499 1958.1 7.855 2,733.3 8.493 1805.4 11.296 1690.2 10.032 2,559.2 4.019 1063.2 9.92

8.518 1713.6 6.949 2013.0 8.915 2,941.8 9.314 1858.8 10.135 2,545.7 4.320 1092.2 10.83

9.001 1728.9 7.390 2058.3 10.183 3,172.7 9.792 1869.9 11.152 2,698.7 4.577 1121.6 11.73

9.406 1768.5 7.982 2096.8 10.287 3,172.5 10.392 1867.4 12.125 2,842.6 4.884 1143.5 11.86

9.915 1789.4 8.471 2140.7 11.272 3,398.3 10.970 1859.5 12.906 2,977.5 5.111 1174.9 12.82

12.466 3,623.6
B-19

Table B2. (Contd.) 

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm

693-01V 290°C 691-07T 290°C 691-03T 290°C 691-06T 290°C 691-02T 290°C 691-03T 290°C 691-05T 290°C 697-01

- - 320°C 30000 h 320°C 50000 h 350°C 2570 h 350°C 10000 h 350°C 30000 h 400°C 2570 h 400°

0.000 48.2 0.072 15.1 0.010 15.55 0.035 20.1 0.005 38.3 0.078 56.4 0.038 58.4 0.15

0.006 63.8 0.303 42.5 0.000 43.62 0.059 69.3 0.124 64.9 0.097 87.3 0.083 24.7 0.193 

0.003 80.6 0.032 74.1 0.085 75.73 0.126 49.0 0.068 92.7 0.187 118.3 0.085 83.1 0.000 

0.000 129.2 0.066 108.9 0.064 110.16 0.177 39.9 0.236 122.2 0.211 149.9 0.079 116.8 0.425 

0.302 152.4 0.223 144.3 0.246 146.07 0.040 109.6 0.160 153.4 0.400 182.8 0.064 193.1 0.312 

0.196 175.9 0.260 182.2 0.150 184.77 0.048 273.0 0.475 184.5 0.337 224.4 0.138 186.4 0.544 

0.291 199.1 0.158 221.5 0.557 221.17 0.020 324.6 0.456 217.5 0.543 266.4 0.168 143.7 0.816 

0.366 220.3 0.324 260.1 0.452 261.37 0.193 315.2 0.580 251.5 0.650 315.7 0.256 226.8 1.015 

0.490 273.8 0.136 303.1 0.925 298.18 0.276 353.1 0.834 283.8 0.950 363.8 0.247 269.5 1.056 

0.405 326.2 0.528 340.3 0.866 332.13 0.327 353.0 0.900 323.4 1.209 405.7 0.466 265.0 1.473 

0.636 352.5 0.349 384.4 0.734 370.71 0.347 417.9 0.894 356.0 1.562 442.9 0.605 305.4 1.727 

0.915 376.0 0.670 423.2 1.121 400.57 0.543 471.2 1.224 387.5 1.742 484.2 0.815 348.1 1.985 

0.969 403.8 0.921 459.3 1.139 434.34 0.645 466.5 1.103 426.8 1.857 528.3 1.047 391.8 2.143 

1.118 461.9 0.961 502.4 1.637 459.67 0.936 528.5 1.263 462.5 2.351 562.3 1.455 457.7 2.640 

1.294 486.3 1.440 534.2 1.768 490.28 1.254 595.0 1.458 496.4 2.449 603.5 1.889 518.9 2.876 

1.371 518.2 1.398 578.7 2.197 515.46 1.356 590.2 1.617 530.0 2.942 634.2 2.322 584.2 3.325 

1.610 541.6 1.772 614.2 2.207 550.16 1.661 652.4 1.938 559.7 3.199 670.2 3.047 667.3 3.579 

1.868 588.8 1.781 656.9 2.265 593.38 2.180 735.1 1.908 597.5 3.557 708.5 3.580 746.1 4.078 

1.994 610.3 2.124 690.2 2.814 618.81 2.842 839.4 2.318 624.3 3.852 748.1 3.669 750.0 4.474 

2.283 628.1 2.267 729.1 2.896 656.74 3.677 956.2 2.406 659.8 4.529 777.1 4.779 864.2 5.163 

2.496 675.5 2.743 761.9 3.474 691.9 4.571 1,077.5 2.822 683.7 4.983 809.9 4.897 868.1 5.862 

2.886 718.8 3.219 791.0 3.819 731.76 5.914 1,228.4 2.900 714.5 5.459 848.4 5.859 970.5 6.590 

3.158 741.2 3.262 848.1 4.469 756.23 7.302 1,355.6 3.220 739.7 6.079 882.7 7.324 1,112.2 7.400 

3.427 763.2 3.762 882.6 4.987 781.51 8.823 1,506.6 3.451 775.1 6.849 901.2 7.413 1,112.2 7.71

3.477 804.1 4.083 937.2 5.527 816.91 10.255 1,661.5 3.846 809.6 7.642 922.8 9.012 1,265.7 8.746 

3.740 832.8 4.912 971.4 6.221 840.02 10.329 1,657.6 4.183 851.4 8.485 933.3 9.130 1,265.6 9.344 

4.153 853.4 5.366 1023.2 6.651 874.06 11.731 1,773.0 4.696 897.2 9.210 945.9 10.758 1,391.4 9.913 

4.521 876.0 6.140 1049.2 7.241 896.09 12.912 1,900.1 5.205 938.8 9.785 965.9 12.490 1,540.9

5.006 891.3 6.618 1103.0 7.743 930.77 5.797 985.4 10.380 979.4

5.263 916.9 7.317 1134.7 8.415 947.15 6.518 1016.9

5.610 943.3 7.821 1176.7 9.017 962.55 7.112 1049.1

6.069 957.9 8.444 1203.5 7.801 1068.9

6.466 986.6 8.935 1235.6 8.522 1079.0

6.881 1024.0 9.571 1246.1 9.028 1101.9

8.128 1068.2 10.297 1235.9 9.630 1112.9

9.277 1123.3 10.164 1135.8
B-20

Table B2. (Contd.) 

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm

CF-8 Materials

683-05B 25°C 683-05T 25°C 683-03V 25°C 683-06T 25°C 682-06T 25°C 683-02B 25°C 682-05V 25°C 681-04

- - - - - - Annealed - 320°C 30000 h 320°C 52600 h 320°C 52600 h 350°

0.216 122.3 0.181 77.8 0.076 89.0 0.000 54.4 0.000 57.1 0.008 32.5 0.000 31.8 0.043 

0.329 115.5 0.292 253.5 0.165 146.8 0.000 111.3 0.045 103.7 0.000 92.5 0.000 89.5 0.072 

0.266 151.2 0.423 293.5 0.188 191.3 0.000 160.2 0.009 143.3 0.078 161.6 0.081 155.2 0.10

0.353 298.0 0.453 375.9 0.291 302.5 0.027 215.1 0.071 190.6 0.135 215.9 0.172 206.4 0.115 

0.457 389.2 0.570 335.7 0.450 346.9 0.029 273.8 0.167 230.8 0.129 272.9 0.098 260.7 0.22

0.686 429.1 0.632 380.2 0.508 331.3 0.000 334.6 0.090 332.7 0.112 332.3 0.196 316.1 0.31

0.779 455.8 0.845 444.6 0.585 415.8 0.145 393.7 0.267 439.4 0.220 391.4 0.349 370.9 0.28

0.863 513.6 1.046 524.6 0.686 440.3 0.258 455.8 0.208 487.5 0.135 454.1 0.384 427.1 0.39

1.092 566.9 1.409 620.1 0.976 495.7 0.154 518.1 0.388 531.9 0.312 514.1 0.478 485.1 0.41

1.040 622.6 1.934 756.2 1.002 564.7 0.313 581.1 0.447 587.7 0.519 572.0 0.580 541.9 0.46

1.036 640.4 2.402 883.3 1.374 651.3 0.388 644.9 0.526 644.0 0.604 632.3 0.745 596.7 0.56

1.358 700.3 3.002 1,017.1 1.672 753.5 0.321 714.7 0.514 703.9 0.666 695.7 0.864 652.1 0.643 

1.660 786.9 3.730 1,172.1 2.201 949.1 0.343 782.8 0.814 753.7 0.791 758.1 1.184 701.4 0.76

1.985 866.8 4.359 1,325.7 2.594 977.0 0.571 843.8 0.866 809.6 0.947 816.5 1.331 753.8 0.828 

2.135 946.9 5.196 1,496.0 3.145 1,113.0 0.559 912.5 0.947 868.7 1.010 879.6 1.463 809.3 0.842 

2.589 1,032.8 6.062 1,634.9 3.820 1,266.9 0.755 975.3 1.129 920.2 1.074 944.7 1.602 863.9 1.04

2.911 1,108.6 6.986 1,791.8 4.521 1,392.8 0.760 1045.4 1.397 1028.8 1.216 1,004.4 2.081 901.0 1.153 

3.443 1,217.9 7.705 1,948.6 5.489 1,536.3 0.943 1108.6 1.625 1088.2 1.441 1,059.5 2.326 942.6 1.26

3.714 1,351.7 7.970 1,939.7 6.561 1,702.2 1.046 1172.9 1.709 1136.0 1.637 1,114.7 2.565 986.1 1.38

4.403 1,491.2 8.953 2,096.6 7.236 1,854.5 1.225 1235.0 1.850 1185.8 1.798 1,171.1 2.801 1049.5 1.503 

5.108 1,625.7 9.907 2,240.1 7.926 1,997.9 1.103 1317.6 2.153 1216.3 1.884 1,239.7 3.106 1107.7 1.722 

5.812 1,778.0 10.494 2,387.9 8.630 2,132.3 1.461 1366.5 2.479 1289.7 2.102 1,281.1 3.551 1151.4 1.785 

6.707 1,912.5 10.978 2,567.0 9.525 2,298.1 1.484 1435.6 2.811 1374.4 2.563 1,375.1 3.946 1215.7 1.83

7.471 2,055.9 11.140 2,567.1 10.318 2,477.4 1.548 1507.5 3.028 1478.4 2.876 1,414.0 4.202 1288.9 2.124 

8.263 2,194.9 12.182 2,710.6 11.067 2,647.6 1.581 1579.0 3.320 1530.8 3.165 1,474.5 4.668 1343.8 2.458 

8.850 2,356.1 12.417 2,710.6 11.800 2,782.0 1.767 1639.1 3.812 1596.0 3.345 1,542.4 5.395 1362.4 2.758 

9.892 2,522.0 12.769 2,952.4 1.999 1689.8 4.264 1644.5 3.879 1,597.1 5.970 1385.5 3.13

11.008 2,692.3 2.192 1753.5 4.715 1684.1 4.470 1,740.3 6.446 1437.1 3.55

11.962 2,835.8 2.282 1828.9 5.102 1732.1 5.114 1,790.6 6.722 1509.4 4.10

13.019 2,961.4 2.640 1886.1 5.454 1780.2 5.633 1,842.7 7.258 1552.1 4.68

13.136 2,961.4 3.018 1948.3 5.774 1848.4 6.155 1,888.2 8.034 1563.7 5.39

3.071 2036.3 6.108 1914.8 6.932 1,905.8 8.798 1558.0 6.518 

3.429 2089.9 6.958 2021.3 7.550 1,933.3 9.310 1583.9 7.384 

3.746 2173.3 7.351 2078.7 8.243 1,943.9 8.352 

4.087 2261.1 7.874 2125.1 8.759 1,976.1 9.21

4.764 2327.4 8.342 2191.2 9.164 2,023.8 10.15

8.625 2285.6 10.27
B-21

Table B2. (Contd.) 

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm

682-04T 25°C 681-06V 25°C 681-03B 25°C 681-01T 25°C 681-03V 25°C 682-08B 25°C 681-04T 25°C 681-05

350°C 30000 h 350°C 30000 h 400°C 2570 h 400°C 10000 h 400°C 10000 h 400°C 10000 h 450°C 2570 h 450°

0.017 29.8 0.049 40.1 0.035 24.3 0.000 27.1 0.044 35.0 Annealed - 0.046 30.6 0.13

0.135 58.6 0.000 68.8 0.101 28.6 0.007 60.3 0.031 60.3 400°C 10000 0.147 190.6 0.058 

0.169 102.8 0.061 100.7 0.140 143.8 0.063 93.2 0.002 75.5 0.000 62.9 0.247 190.3 0.208 

0.219 125.9 0.174 134.4 0.221 148.1 0.136 117.1 0.142 118.8 0.000 112.2 0.270 242.9 0.35

0.399 150.4 0.190 175.9 0.210 192.4 0.000 141.4 0.186 144.3 0.000 166.2 0.375 295.3 0.47

0.208 174.9 0.354 218.6 0.260 254.4 0.131 168.2 0.308 170.9 0.129 222.4 0.587 353.9 0.51

0.284 201.9 0.550 260.4 0.225 298.7 0.279 193.2 0.302 197.0 0.098 280.8 0.675 430.4 0.633 

0.443 227.0 0.662 303.2 0.299 345.1 0.177 220.4 0.420 234.6 0.255 340.3 0.868 515.5 1.023 

0.516 252.1 0.880 345.2 0.427 398.1 0.229 274.4 0.473 272.7 0.386 400.1 0.949 462.5 1.35

0.554 278.7 1.161 384.8 0.462 460.1 0.376 302.6 0.447 301.9 0.532 459.7 1.092 519.1 1.678 

0.571 308.1 1.489 422.3 0.474 378.1 0.451 329.2 0.518 331.4 0.646 509.8 1.574 596.6 2.32

0.624 332.6 1.762 459.4 0.598 515.3 0.679 377.4 0.576 360.3 0.762 559.5 1.898 683.4 3.044 

0.704 359.6 2.093 494.7 0.804 570.3 0.586 411.9 0.642 389.8 1.007 606.5 2.408 767.3 3.44

0.719 396.4 2.300 531.7 0.983 663.1 0.743 450.7 0.838 426.7 1.169 684.5 3.018 872.9 3.964 

0.867 432.0 2.685 573.5 1.177 744.7 0.947 512.9 1.049 461.6 1.326 722.9 3.355 986.9 4.592 

1.050 465.8 3.070 621.1 1.469 835.1 1.213 543.7 1.301 497.2 1.490 768.1 3.927 1,091.5 4.91

1.232 499.5 3.523 672.2 1.721 925.5 1.523 570.3 1.575 532.1 1.702 813.3 4.661 1,227.7 5.665 

1.490 529.6 4.073 724.5 2.133 1,040.0 1.697 596.9 1.651 567.5 2.036 850.5 5.322 1,359.9 6.58

1.737 560.2 4.597 781.0 2.473 1,166.8 1.847 629.4 1.826 603.3 2.275 889.0 9.308 1,462.9 7.41

2.222 617.7 7.065 749.9 2.909 1,313.7 2.364 672.3 2.201 632.3 2.642 921.0 10.448 1,527.3 8.27

2.524 642.6 8.128 740.1 3.750 1,491.5 2.523 693.9 2.385 674.8 2.952 962.8 11.210 1,619.1 9.595 

2.696 679.4 9.028 756.3 4.533 1,672.4 2.790 725.9 2.606 717.8 3.301 1,002.7 11.752 1,711.5 10.63

3.021 712.3 5.149 1,860.4 2.997 753.2 2.740 772.9 3.739 1,032.5 12.908 1,829.3 11.93

3.248 746.2 5.838 2,076.2 3.175 782.8 2.923 827.2 4.263 1,054.8 13.63

3.597 784.6 6.673 2,291.6 3.630 812.9 3.229 874.6 4.710 1,073.0 13.95

3.816 835.5 7.639 2,551.3 3.666 839.0 3.588 937.3 5.059 1,100.0

4.269 883.4 8.475 2,800.1 3.928 866.7 3.895 998.3 5.461 1,132.3

4.762 923.5 9.442 3,076.5 4.112 895.0 4.664 1047.5 6.034 1,149.9

5.185 963.4 10.715 3,329.9 4.205 930.6 5.369 1087.9 6.750 1,147.8

5.692 1026.5 10.817 3,329.7 4.458 953.0 6.319 1120.6 7.276 1,157.9

6.379 988.1 4.640 980.4 6.952 1186.7 7.702 1,177.9

6.888 1031.7 5.218 982.1 7.572 1250.2 8.097 1,216.8

7.225 1110.7 5.561 1051.6 8.697 1263.5 8.421 1,260.8

7.642 1173.9 5.869 1082.3 9.901 1258.9 8.729 1,304.6

8.181 1250.8 6.133 1115.5 10.959 1264.4 9.104 1,338.9

6.754 1171.1 9.597 1,353.1

7.083 1192.7 9.981 1,371.7
B-22

Table B2. (Contd.) 

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm

C341 54°C 683-07T 290°C 683-06B 290°C 682-07T 290°C 683-02T 290°C 681-06T 290°C 682-03T 290°C 682-05

350°C 138000 h - - Annealed - 320°C 30000 h 320°C 52600 h 350°C 2570 h 350°C 10000 h 350°

0.43 307.6 0.038 51.2 0.028 28.0 0.154 15.8 0.000 44.6 0.077 24.4 0.158 67.4 0.000 

0.65 386.7 0.063 211.4 0.107 93.2 0.081 99.1 0.389 77.2 0.043 55.4 0.010 128.1 0.028 

1.03 494.4 0.039 282.6 0.138 131.6 0.221 128.7 0.015 112.3 0.125 139.7 0.345 159.9 0.068 

1.43 591.5 0.093 311.5 0.071 175.5 0.000 160.2 0.431 148.9 0.149 172.9 0.105 193.1 0.190 

1.89 692.4 0.073 347.1 0.007 215.2 0.295 190.6 0.222 192.2 0.129 206.2 0.357 226.0 0.065 

2.37 782.1 0.010 456.2 0.157 259.9 0.299 221.4 0.497 239.9 0.148 239.5 0.120 262.2 0.003 

2.90 873.6 0.132 574.1 0.082 301.7 0.469 253.1 0.438 280.7 0.240 279.4 0.555 293.7 0.219 

3.67 994.4 0.272 609.6 0.386 342.2 0.537 286.0 0.000 329.7 0.288 310.4 0.524 328.1 0.090 

0.411 649.6 0.526 384.8 0.783 316.8 0.600 356.0 0.370 341.5 0.663 363.0 0.366 

0.461 689.7 0.572 430.5 0.816 350.9 0.661 387.8 0.432 381.4 0.678 399.9 0.398 

0.620 729.6 0.739 475.1 0.880 385.6 0.818 421.4 0.606 419.1 0.920 432.5 0.584 

0.844 789.6 0.827 520.7 1.040 418.5 1.149 449.9 0.698 452.3 1.094 466.1 0.59

1.162 856.2 1.126 562.1 1.214 450.8 1.492 477.2 0.795 492.2 1.161 503.4 0.825 

1.193 856.2 1.203 607.6 1.281 485.6 1.811 532.9 0.765 529.9 1.476 533.2 0.739 

1.425 909.4 1.452 649.6 1.510 516.3 2.096 554.2 0.799 589.8 1.739 602.8 1.089 

1.766 967.1 1.626 692.9 1.609 549.3 2.257 577.7 0.837 589.8 1.842 638.4 1.444 

1.940 1,037.3 1.797 737.3 1.951 575.9 2.189 609.1 0.948 645.2 2.092 669.0 1.723 

2.236 1,093.1 2.025 780.0 2.058 608.4 2.665 630.0 1.219 702.9 2.338 697.9 1.940 

2.530 1,160.0 1.886 836.6 2.368 634.2 3.054 649.5 1.499 787.1 2.510 730.8 2.004 

2.899 1,235.8 2.310 868.8 2.544 663.6 3.225 684.6 1.843 853.7 2.681 763.2 2.323 

3.276 1,316.1 2.563 906.7 2.789 691.5 3.657 709.2 2.248 937.0 2.866 806.9 2.739 

3.660 1,387.4 2.749 948.0 3.160 745.7 3.986 734.8 2.820 1,022.5 3.145 844.5 2.930 

4.198 1,491.2 3.018 992.8 3.539 779.9 4.359 765.1 3.512 1,139.4 3.365 897.8 3.259 

4.667 1,589.8 3.269 1,037.5 3.935 815.3 4.768 791.3 4.284 1,288.4 3.674 943.6 3.440 

5.416 1,683.9 3.362 1,106.7 4.311 865.5 5.216 818.5 5.330 1,443.8 4.265 986.0 3.825 

6.135 1,782.6 3.805 1,151.0 4.755 909.1 5.690 843.2 6.609 1,571.0 4.651 1036.8 4.179 

6.928 1,845.5 4.121 1,216.7 5.517 928.0 6.127 866.8 8.134 1,725.3 5.116 1094.6 4.716 

7.427 1,939.6 4.505 1,276.3 6.020 972.6 6.626 885.3 9.341 1,872.1 5.675 1141.3 5.212 

8.234 2,033.8 4.928 1,343.0 6.643 1003.3 6.948 912.3 10.387 2,023.0 6.272 1178.8 5.84

9.129 2,141.4 5.549 1,387.1 7.167 1036.2 7.476 923.8 11.433 2,119.3 6.978 1200.9 6.349 

9.760 2,240.0 5.915 1,450.8 7.787 1058.2 7.776 947.0 12.320 2,258.6 7.436 1239.8 6.858 

10.303 2,325.2 6.336 1,509.5 8.192 1093.3 8.311 953.0 13.366 2,366.6 8.067 1260.0 7.245 

10.920 2,414.9 6.780 1,562.5 8.709 1116.3 8.447 985.9 8.658 1276.9 7.574 

11.463 2,495.6 7.052 1,630.0 9.356 1122.0 8.964 990.1 9.048 1312.1 8.183 

11.947 2,598.6 9.869 1131.7 9.341 1000.1 9.639 1322.3 8.79

12.167 2,630.0 10.351 1142.5 9.657 1014.9 10.126 1335.2 9.238 

12.534 2,706.2 10.011 1024.1 10.26
B-23

Table B2. (Contd.) 

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm

681-02T 290°C 681-03T 290°C C1B-03 25°C C1B-01 25°C C1B-02 23°C C1B-18 25°C C1B-08 25°C C1B-1

400°C 10000 h 450°C 2570 h - - - - - - 320°C 30000 h 350°C 10000 h 350°

0.000 29.2 0.031 22.3 0.115 31.2 0.069 44.4 0.053 32.9 0.000 19.5 0.000 51.8 0.000 

0.086 70.8 0.093 51.2 0.130 90.4 0.064 95.3 0.149 75.6 0.000 53.8 0.037 88.9 0.000 

0.015 118.6 0.018 174.1 0.191 141.3 0.148 123.2 0.160 110.1 0.025 92.2 0.113 128.6 0.11

0.000 144.9 0.107 227.5 0.228 185.7 0.129 151.2 0.206 126.5 0.259 132.5 0.090 168.8 0.110 

0.171 170.8 0.255 267.4 0.293 223.4 0.213 207.0 0.325 179.1 0.263 174.9 0.214 210.4 0.119 

0.243 195.8 0.286 305.3 0.231 246.4 0.312 246.4 0.405 197.2 0.320 219.0 0.334 252.5 0.279 

0.347 222.6 0.555 342.8 0.297 257.9 0.443 284.2 0.443 231.7 0.365 264.7 0.518 295.0 0.372 

0.502 248.4 0.726 427.4 0.442 299.0 0.438 326.9 0.493 271.1 0.436 310.6 0.666 337.1 0.496 

0.629 275.0 0.765 387.1 0.488 343.4 0.726 369.7 0.600 289.2 0.570 356.6 0.946 377.5 0.696 

0.620 303.5 0.874 471.8 0.587 387.7 0.972 405.8 0.700 330.2 0.813 400.9 1.180 418.0 0.835 

0.463 335.5 1.185 509.2 0.663 453.5 1.160 453.5 0.753 349.9 1.017 445.7 1.455 456.7 0.919 

0.788 360.5 1.384 555.7 0.830 517.7 1.521 497.8 0.768 369.7 1.202 482.4 1.806 493.5 1.170 

0.866 388.1 1.481 598.0 1.023 588.9 1.785 538.9 0.880 389.4 1.282 521.4 2.125 528.0 1.214 

1.093 412.4 1.781 599.7 1.254 662.7 2.162 580.0 0.964 412.4 1.524 556.9 2.486 561.5 1.28

1.231 437.6 2.170 663.8 1.461 755.8 2.826 642.4 1.006 430.4 1.814 589.3 2.718 606.5 1.68

1.539 489.7 2.539 730.7 1.913 855.9 3.384 688.4 1.087 451.8 1.842 629.1 2.995 650.0 1.714 

1.850 542.0 2.874 810.6 2.017 847.6 1.527 492.8 1.125 474.8 2.230 658.0 3.331 698.1 1.954 

2.006 575.3 4.003 882.5 2.396 940.6 1.787 541.2 1.224 496.2 2.431 699.5 3.666 744.2 2.228 

2.371 597.7 4.091 886.4 2.678 1,042.9 2.158 581.0 1.359 515.9 2.688 739.0 4.027 788.6 2.442 

2.681 622.5 4.864 967.6 2.718 1,033.4 2.826 640.0 1.394 534.8 3.073 771.8 4.486 825.8 3.095 

2.890 651.5 5.301 1,025.7 3.188 1,152.0 3.383 686.6 1.562 555.3 3.551 798.1 4.963 860.6 3.536 

3.286 679.4 5.885 1,103.2 3.730 1,276.4 4.101 731.8 1.587 579.7 3.843 829.5 6.004 878.4 3.827 

3.672 713.0 7.197 1,207.3 4.471 1,425.1 4.324 774.6 1.677 609.5 4.212 866.9 6.863 885.3 4.206 

4.151 747.7 8.757 1,322.9 5.189 1,562.1 5.089 826.0 1.783 649.7 4.603 901.3 7.226 922.0 4.61

4.602 781.2 10.055 1,442.7 6.162 1,699.0 5.775 885.9 2.035 686.6 4.948 944.4 7.408 990.0 5.075 

4.990 830.3 11.397 1,574.1 7.008 1,823.1 6.317 924.4 2.178 733.6 5.519 970.1 7.880 1,036.3 5.258 

5.491 870.9 12.695 1,701.6 7.773 1,947.2 6.477 928.7 2.463 775.0 6.117 988.2 8.302 1,079.4 5.706 

5.841 916.8 8.635 2,122.7 6.955 984.3 2.641 817.0 6.647 1,006.8 8.738 1,117.4 6.10

6.551 935.9 9.433 2,251.1 7.466 1,027.1 3.193 917.6 7.139 1,041.0 9.308 1,138.4 6.45

7.106 957.1 9.640 2,276.7 8.072 1,095.6 3.826 1,017.4 7.928 1,047.0 10.192 1,114.0 6.83

7.639 979.2 10.533 2,388.0 8.869 1,168.3 4.485 1,117.0 8.543 1,056.5 7.40

8.300 986.0 11.491 2,537.8 9.858 1,258.2 5.012 1,219.7 9.032 1,076.0 7.920 

8.664 1012.0 11.634 2,559.2 10.639 1,339.5 5.985 1,356.6 9.530 1,091.5 8.674 

9.171 1027.9 13.468 2,636.2 10.735 1,339.5 6.878 1,493.6 10.036 1,101.8 9.084 

9.657 1034.3 13.595 2,653.4 12.043 1,433.7 7.788 1,656.2 9.543 

10.098 1045.4 12.824 1,532.1 9.367 1,835.9 10.03

10.551 1051.5 12.968 1,540.7 9.830 1,930.1 10.51

10.755 2,092.7
B-24

Table B2. (Contd.) 

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm

C1B-05 290°C C1B-19 290°C C1B-09 290°C C1B-12 290°C P1B-03 25°C P1B-01 25°C P1T-01 25°C P1T-1

- - 320°C 30000 h 350°C 10000 h 350°C 30000 h - - - - - - 290°

0.042 19.1 0.128 14.9 0.035 35.0 0.000 21.4 0.107 78.5 0.512 464.8 0.275 353.8 0.036 

0.053 50.4 0.283 37.4 0.011 58.6 0.165 43.9 0.260 229.1 0.642 497.3 0.343 471.8 0.040 

0.088 27.2 0.217 62.5 0.282 82.8 0.052 68.5 0.405 307.5 0.909 719.9 0.870 864.4 0.139 

0.111 42.2 0.191 89.8 0.234 109.2 0.320 94.1 0.557 536.9 1.146 903.1 1.008 1,021.6 0.095 

0.068 83.1 0.182 117.9 0.328 136.3 0.031 122.5 0.726 635.0 1.268 955.3 0.984 1,166.1 0.072 

0.140 128.1 0.466 146.0 0.254 165.8 0.158 150.5 0.656 746.7 1.337 1,007.6 1.160 1,310.1 0.144 

0.213 160.8 0.284 177.3 0.319 194.7 0.108 180.1 1.001 844.4 1.406 1,079.7 1.266 1,493.6 0.298 

0.327 216.6 0.692 205.4 0.590 222.0 0.038 216.1 1.031 916.5 1.528 1,125.3 1.511 1,676.8 0.274 

0.312 243.9 0.455 239.1 0.603 252.4 0.253 249.6 1.237 1,060.4 1.674 1,177.5 1.663 1,879.9 0.406 

0.461 256.1 0.824 268.1 0.848 281.1 0.431 283.6 1.597 1,230.2 1.781 1,242.9 1.908 2,082.8 0.315 

0.552 288.8 0.881 299.9 0.771 314.6 0.722 316.4 2.082 1,469.3 1.903 1,308.2 2.053 2,082.5 0.422 

0.621 287.4 0.995 332.5 0.753 348.5 0.871 351.8 2.531 1,592.7 2.311 1,501.8 2.374 2,259.3 0.564 

0.747 335.1 1.212 363.0 0.957 378.3 1.029 387.6 2.877 1,739.3 2.627 1,651.8 2.634 2,462.2 0.616 

0.976 375.9 1.222 397.8 0.951 412.0 1.240 422.2 3.183 1,832.2 3.079 1,832.4 3.094 2,737.3 0.584 

1.320 435.8 1.663 423.8 1.460 434.4 1.753 438.1 3.545 1,956.9 3.543 2,015.1 3.546 3,026.7 0.649 

1.645 497.0 1.663 458.4 1.708 460.7 1.600 480.6 3.764 2,086.1 4.146 2,211.9 4.081 3,289.5 0.784 

1.921 563.3 2.085 483.1 2.154 482.3 2.178 506.3 4.156 2,207.5 4.855 2,397.4 4.774 3,557.5 0.912 

2.420 646.6 2.079 518.3 2.257 512.3 2.188 545.1 4.495 2,364.0 5.586 2,595.0 5.361 3,911.6 0.952 

2.777 730.7 2.462 543.8 2.688 545.2 2.643 572.1 4.789 2,518.5 6.463 2,816.5 6.011 4,234.7 0.906 

3.432 829.3 2.556 576.3 2.836 585.5 2.840 611.4 5.307 2,708.8 7.319 3,036.9 6.643 4,576.5 1.007 

3.950 926.7 2.731 607.3 3.160 620.3 3.243 644.0 5.785 2,884.9 8.100 3,285.8 7.287 4,909.5 1.200 

4.783 1,025.9 3.185 632.2 3.443 655.1 3.538 678.4 6.243 3,128.0 8.413 3,356.1 7.931 5,250.1 1.26

5.475 1,120.1 3.433 663.7 4.057 686.2 4.099 712.3 7.016 3,369.6 8.602 5,574.6 1.215 

5.616 1,120.1 3.851 688.4 4.422 724.9 4.365 757.4 7.818 3,597.8 9.131 5,839.0 1.424 

6.138 1,211.1 4.050 720.6 4.998 752.0 4.845 791.8 8.304 3,798.2 1.647 

7.099 1,337.8 4.658 739.3 5.329 789.2 5.119 834.1 9.014 3,965.2 1.656 

8.087 1,474.2 4.705 783.2 5.819 816.2 5.830 860.8 9.555 4,167.7 1.62

8.228 1,487.2 5.170 819.0 6.261 842.9 6.372 892.5 10.229 4,370.1 1.738 

9.570 1,607.5 5.626 850.8 6.675 870.5 6.889 922.6 1.980 

10.728 1,721.2 6.135 875.8 7.011 901.4 7.411 949.6 2.008 

10.884 1,737.5 6.523 905.3 7.343 931.4 7.841 980.0 2.397 

12.000 1,841.5 7.119 917.6 7.677 959.5 8.220 1,000.8 2.517 

12.861 1,958.5 7.689 927.1 8.178 971.8 8.623 1,029.0 2.923 

12.917 1,965.0 8.355 924.0 8.648 982.9 9.194 1,048.1 3.295 

8.649 948.7 8.932 1,007.7 9.623 1,075.4 3.574 

9.578 963.5 9.375 1,018.6 9.375 1,018.6 3.998 

10.114 960.7 9.689 1,035.2 9.689 1,035.2 4.450 
B-25

Table B2. (Contd.) 

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm

P1B-14 25°C P1T-08 25°C P1B-06 25°C P1T-06 25°C P1B-09 25°C P1B-05 25°C P1T-04 25°C P1B-0

320°C 55000 h 350°C 10000 h 350°C 10000 h 350°C 10000 h 350°C 30000 h 400°C 10000 h 400°C 10000 h - 

0.000 33.1 0.035 46.4 0.136 189.3 0.106 84.8 0.000 53.2 0.106 71.8 0.355 261.2 0.10

0.000 92.2 0.042 96.1 0.157 391.9 0.212 215.3 0.134 82.9 0.174 182.7 0.522 313.6 0.032 

0.074 125.5 0.143 129.0 0.225 463.7 0.394 332.7 0.198 131.7 0.409 215.7 0.705 352.9 0.01

0.102 159.3 0.251 244.9 0.293 574.7 0.385 476.5 0.223 172.3 0.477 333.0 1.130 431.8 0.064 

0.089 194.4 0.324 321.0 0.326 274.0 0.590 567.7 0.285 247.0 0.596 561.2 1.214 412.4 0.195 

0.029 231.1 0.763 425.8 0.384 639.9 0.811 665.3 0.322 306.3 1.001 451.1 1.503 517.1 0.348 

0.206 267.5 0.938 549.5 0.583 561.1 1.486 1,200.2 0.325 368.9 1.388 529.9 1.959 583.0 0.578 

0.089 305.4 1.318 660.0 0.635 691.8 1.835 1,369.6 0.347 437.0 1.479 627.8 2.409 643.6 0.545 

0.136 344.4 1.631 784.5 0.871 730.6 2.323 1,631.8 0.521 502.4 1.563 621.4 3.031 721.2 0.72

0.176 421.9 1.816 883.7 0.946 959.2 2.736 1,723.7 0.674 569.7 1.968 722.9 3.495 801.0 0.80

0.230 502.2 2.097 972.7 1.121 1,004.7 3.354 1,962.1 0.871 625.4 2.708 780.9 4.280 867.7 1.048 

0.366 541.0 2.080 1,073.2 1.173 1,135.3 4.174 2,244.6 0.896 668.7 3.236 856.3 5.358 945.6 1.135 

0.481 578.8 2.270 1,104.9 1.516 1,226.3 4.938 2,532.2 0.998 741.5 3.837 927.4 6.224 999.4 1.31

0.541 618.7 2.526 1,221.3 1.878 1,355.7 5.809 2,869.8 1.245 828.7 4.418 1,011.6 6.759 1,065.1 1.66

0.506 662.2 2.835 1,350.3 2.261 1,539.0 6.677 3,186.0 1.322 850.6 4.890 1,078.2 6.995 1,075.0 1.955 

0.607 702.1 3.136 1,478.6 2.532 1,730.1 7.382 3,480.4 1.427 868.9 5.605 1,178.8 7.397 1,113.3 2.228 

0.675 742.4 3.420 1,616.5 3.220 1,879.6 8.198 3,806.2 1.515 912.8 6.287 1,268.4 8.252 1,156.8 2.60

0.620 787.9 3.799 1,747.2 3.861 2,040.1 9.560 4,265.2 1.588 935.4 7.063 1,376.6 9.321 1,199.8 2.895 

0.695 831.1 4.499 1,952.4 10.251 4,496.8 1.746 995.6 7.834 1,493.5 10.255 1,269.1 3.37

0.927 864.5 4.861 2,061.8 10.420 4,548.3 1.915 1029.0 8.324 1,593.4 10.808 1,347.4 3.84

0.970 995.4 5.179 2,218.0 11.238 4,797.0 2.169 1104.5 8.496 1,593.3 11.284 1,425.7 4.08

1.102 1033.7 5.323 2,350.7 12.522 5,062.6 2.616 1175.4 9.182 1,697.7 11.779 1,521.5 4.535 

1.207 1118.2 5.917 2,514.8 12.719 5,122.7 2.786 1211.2 9.411 1,732.5 4.885 

1.352 1156.3 6.351 2,678.8 3.028 1217.6 10.173 1,828.1 5.344 

1.470 1191.7 6.234 2,850.4 3.214 1250.7 11.508 1,940.9 5.858 

1.691 1220.5 6.639 2,967.6 3.371 1263.2 12.385 2,053.9 6.503 

1.778 1257.7 7.103 3,123.8 3.578 1298.5 7.40

1.902 1294.6 7.624 3,272.3 3.811 1367.8 8.05

2.250 1379.5 8.276 3,483.3 4.062 1404.6 8.538 

2.569 1464.8 9.116 3,678.7 4.216 1424.6 9.172 

2.952 1499.0 9.680 3,913.0 4.394 1447.1 9.774 

3.400 1611.1 10.317 4,123.9 4.845 1505.1 

4.278 1693.4 10.722 4,342.6 5.307 1567.4

5.317 1800.8 11.359 4,553.5 5.872 1602.1

6.045 2020.1 12.171 4,709.9 6.233 1646.6

7.130 2184.8 12.316 4,725.6 6.947 1712.8

8.294 2286.0 7.366 1763.7

7.703 1775.9
B-26

Table B2. (Contd.) 

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm

P1T-18 290°C P1B-12 290°C P1B-15 290°C P1B-07 290°C P1T-07 290°C P1B-10 290°C P1T-05 290°C CA4-0

290°C 58000 h 320°C 30000 h 320°C 55000 h 350°C 10000 h 350°C 10000 h 350°C 30000 h 400°C 10000 h 264°

0.117 14.8 0.000 39.7 0.000 41.4 0.057 38.1 0.156 125.2 0.000 53.4 0.055 67.0 0.116 

0.078 68.6 0.000 69.2 0.100 72.2 0.080 111.6 0.079 171.4 0.168 74.9 0.106 75.8 0.05

0.268 99.6 0.029 100.0 0.000 104.8 0.084 204.1 0.088 277.5 0.078 96.6 0.130 116.1 0.09

0.072 132.4 0.114 137.9 0.168 138.7 0.164 266.7 0.102 348.3 0.171 120.1 0.122 152.0 0.008 

0.193 165.9 0.135 178.3 0.000 176.0 0.221 307.5 0.201 389.1 0.138 144.1 0.157 174.3 0.108 

0.000 238.8 0.297 218.9 0.150 212.1 0.283 315.7 0.353 440.9 0.000 170.6 0.224 230.1 0.067 

0.350 295.5 0.000 264.8 0.085 250.1 0.435 370.2 0.405 498.0 0.171 194.8 0.417 292.1 0.144 

0.654 323.4 0.368 305.8 0.200 314.8 0.439 419.2 0.676 560.8 0.257 219.3 0.570 354.3 0.258 

0.338 360.6 0.218 351.9 0.395 371.5 0.710 490.1 0.695 596.1 0.353 244.8 0.830 420.5 0.330 

0.626 390.1 0.415 389.0 0.304 403.4 1.020 547.3 0.757 623.4 0.297 271.7 1.098 484.5 0.320 

0.462 426.3 0.478 427.1 0.522 455.0 1.286 610.1 1.066 702.4 0.499 303.8 1.338 557.5 0.43

0.329 464.7 0.547 466.6 0.730 507.0 1.519 667.3 1.122 811.3 0.531 338.0 1.659 622.9 0.445 

0.830 487.5 0.760 502.3 0.468 545.1 1.918 754.6 1.260 786.9 0.254 377.9 2.086 692.1 0.522 

0.896 519.3 0.939 538.4 0.862 565.0 2.416 835.3 1.665 876.9 0.677 408.6 2.569 762.2 0.566 

1.084 550.2 1.121 575.0 0.787 594.7 2.819 942.0 1.664 901.3 0.463 446.4 2.880 832.8 0.630 

0.802 593.9 1.230 613.4 1.097 615.8 3.600 1,066.7 2.051 977.0 0.861 475.4 3.238 905.5 0.753 

1.023 625.5 1.243 655.4 0.893 651.1 4.255 1,189.9 2.465 1,086.5 0.876 510.5 3.701 998.4 0.804 

0.950 701.6 1.615 685.5 1.003 682.7 4.846 1,313.1 2.972 1,200.0 1.147 541.2 4.195 1,093.3 1.075 

1.176 731.6 1.837 718.5 1.273 698.8 5.768 1,477.4 3.544 1,338.2 1.174 578.1 4.597 1,170.7 1.280 

1.300 763.5 1.959 755.3 1.210 731.0 7.185 1,664.6 4.520 1,566.8 1.463 605.5 4.701 1,188.9 1.436 

1.599 825.8 2.294 828.7 1.377 755.9 5.279 1,675.4 1.581 639.2 5.207 1,248.0 1.673 

1.633 863.6 2.603 856.4 1.479 782.3 6.985 1,976.6 1.939 701.1 5.937 1,348.0 1.790 

1.903 889.2 2.692 893.9 1.635 805.7 7.085 1,987.6 2.250 728.9 6.622 1,420.6 1.946 

2.035 920.1 3.035 926.6 1.764 830.3 8.259 2,174.7 2.162 768.6 6.741 1,420.6 1.985 

2.163 952.4 3.295 961.7 1.660 865.5 9.146 2,356.1 2.618 830.3 7.232 1,497.9 2.186 

2.429 1,015.6 3.372 1015.4 2.167 899.3 10.119 2,581.3 3.119 850.9 7.753 1,584.3 2.415 

2.631 1,050.6 3.626 1074.4 2.470 915.0 11.164 2,768.3 3.292 884.7 8.646 1,693.4 2.502 

2.701 1,092.9 3.772 1137.9 2.890 997.3 11.293 2,795.8 3.786 954.4 9.524 1,811.6 2.827 

2.881 1,128.5 4.330 1184.8 3.327 1,052.1 12.323 2,960.8 4.143 987.3 10.492 1,943.4 3.144 

2.913 1,181.5 4.851 1227.1 3.987 1,154.1 12.481 2,999.3 4.503 1,022.6 11.281 2,066.2 3.57

3.307 1,208.7 5.551 1248.4 4.390 1,182.2 5.033 1,060.3 12.501 2,216.1 3.822 

3.690 1,305.2 6.229 1263.0 5.293 1,251.3 5.709 1,080.6 4.168 

4.146 1,425.7 7.017 1271.3 5.870 1,267.5 6.001 1,140.4 4.850 

4.634 1,458.9 7.606 1294.6 6.710 1,315.9 6.667 1,168.4 5.279 

5.349 1,539.7 8.013 1,335.0 7.305 1,331.3 7.984 1,202.5 5.902 

6.016 1,618.5 8.465 1,366.2 8.023 1,369.6 9.247 1,221.9 6.796 

6.579 1,703.2 9.053 1,375.6 8.758 1,406.4 10.113 1,268.0 7.464 
B-27

Table B2. (Contd.) 

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm

CA4-01B 290°C CA4-02B 290°C MA1-01T 25°C MA1-01B 290°C MA9-01I 25°C MA9-02O 25°C MA9-01O 290°C MA9-0

Annealed - 264°C 113900 h 264°C 113900 h 264°C 113900 h - - 400°C 10000 h - - 400°

0.000 9.4 0.055 20.6 0.028 30.8 0.138 49.2 0.026 16.8 0.009 39.2 0.000 36.1 0.005 

0.161 28.6 0.080 51.6 0.000 92.9 0.193 73.0 0.017 46.2 0.030 73.6 0.172 59.6 0.000 

0.051 53.6 0.035 90.3 0.000 137.3 0.214 98.2 0.096 78.4 0.145 110.4 0.033 88.6 0.072 

0.035 85.4 0.000 113.2 0.130 179.8 0.103 129.6 0.199 112.4 0.140 149.6 0.509 117.7 0.143 

0.053 118.8 0.259 134.8 0.240 224.7 0.068 161.9 0.039 147.4 0.127 190.2 0.091 151.2 0.000 

0.190 152.9 0.094 159.0 0.167 272.5 0.107 199.4 0.057 184.4 0.084 232.7 0.326 184.0 0.228 

0.083 188.9 0.248 181.7 0.110 323.0 0.200 237.0 0.141 219.8 0.202 275.0 0.346 213.4 0.158 

0.379 223.4 0.035 213.9 0.168 372.5 0.154 277.4 0.114 270.4 0.148 319.7 0.076 246.5 0.19

0.254 261.9 0.376 271.9 0.303 421.0 0.316 316.2 0.190 321.7 0.191 379.7 0.255 275.8 0.334 

0.566 296.9 0.255 304.3 0.236 473.8 0.237 359.1 0.244 386.9 0.142 443.3 0.073 309.7 0.392 

0.594 336.3 0.450 334.1 0.376 524.4 0.449 398.3 0.231 455.9 0.203 505.9 0.334 338.2 0.194 

0.719 373.6 0.562 364.7 0.163 601.7 0.277 434.0 0.124 529.2 0.347 550.6 0.171 373.7 0.365 

0.824 411.7 0.766 394.1 0.279 660.2 0.357 466.9 0.322 596.7 0.347 591.1 0.614 399.2 0.384 

0.961 450.0 0.762 427.8 0.332 723.9 0.563 495.4 0.379 668.6 0.407 631.5 0.234 440.8 0.544 

1.020 490.0 0.913 458.9 0.419 784.0 0.312 535.6 0.274 748.5 0.408 683.0 0.549 469.5 0.505 

1.262 526.0 0.921 493.7 0.495 846.7 0.624 562.2 0.410 820.7 0.350 736.1 0.293 511.5 0.743 

1.107 572.9 1.289 519.4 0.518 913.5 0.384 615.6 0.399 899.5 0.535 781.9 0.407 582.4 0.677 

1.518 604.2 1.351 551.9 0.608 976.9 0.750 650.5 0.465 977.7 0.537 833.3 0.195 626.9 0.988 

1.285 654.4 1.337 588.7 0.738 1039.1 0.905 691.0 0.465 1,059.1 0.629 882.8 0.366 659.8 0.868 

1.763 681.4 1.623 615.4 0.738 1109.2 0.993 735.4 0.577 1,137.5 0.642 936.4 0.208 703.8 1.365 

1.644 728.5 1.578 652.2 0.889 1170.3 1.214 781.0 0.676 1,214.2 0.699 987.5 0.586 728.0 1.350 

2.135 753.2 2.061 671.7 1.009 1232.8 1.189 838.1 0.579 1,307.2 0.849 1033.7 0.506 770.8 1.899 

2.149 795.0 2.121 703.5 1.066 1300.0 1.408 889.5 0.738 1,382.2 0.915 1084.4 0.766 799.0 2.168 

2.659 815.6 2.649 765.7 1.141 1367.2 1.511 944.8 0.866 1,459.7 1.025 1133.6 0.672 842.1 2.643 

2.829 849.3 3.066 794.9 1.347 1423.3 2.131 980.6 0.949 1,523.4 1.161 1197.5 0.913 872.3 3.015 

3.122 878.7 3.114 840.3 1.464 1486.3 2.732 1012.1 1.282 1,612.1 1.380 1247.3 0.787 919.2 3.123 

3.415 906.4 3.550 867.3 1.472 1558.6 2.781 1079.8 1.117 1,724.8 1.514 1301.4 0.987 950.9 3.444 

3.960 975.3 3.862 909.2 1.654 1617.2 3.520 1096.9 1.384 1,813.7 1.948 1395.2 0.870 998.5 3.68

4.181 1023.9 4.206 949.1 1.836 1673.3 4.043 1124.5 1.730 1,886.3 2.282 1437.9 0.892 1040.9 3.934 

4.590 1070.7 4.651 991.9 2.125 1715.2 4.298 1173.3 1.974 1,969.5 2.834 1457.7 1.111 1116.2 3.976 

5.036 1112.6 5.006 1037.7 2.368 1761.5 4.636 1215.5 2.342 2,041.9 3.213 1507.9 1.298 1145.9 4.290 

5.379 1158.1 5.643 1070.8 2.539 1813.3 4.870 1265.6 2.638 2,110.1 3.763 1542.0 1.422 1193.9 4.346 

5.839 1205.3 6.118 1110.9 2.677 1870.7 5.129 1313.8 3.097 2,161.1 4.215 1577.4 1.594 1241.1 4.634 

6.348 1243.0 6.585 1149.0 2.929 1933.1 5.427 1355.3 4.713 1624.8 1.872 1369.5 4.983 

6.789 1283.5 7.058 1183.5 2.961 2021.3 5.867 1379.6 5.127 1677.2 2.340 1419.7 5.317 

7.358 1307.4 7.506 1217.9 3.592 2157.1 6.360 1393.6 5.884 1784.7 2.784 1545.8 5.594 

7.778 1342.8 8.114 1231.0 3.996 2204.5 6.473 1817.3 3.580 1649.6 5.936 
B-28

Table B2. (Contd.) 

∆a 

(mm)

J 

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm

PVI-02 25°C PVO-01 25°C PVI-01 290°C PVC-02 25°C PVO-02 25°C VRI-01 25°C VRO-02 25°C VRO-0

264°C 113900 h 400°C 10000 h Annealed - 264°C 113900 h 400°C 10000 h - - 400°C 10000 h - 

0.042 20.0 0.043 39.2 0.000 37.74 0.061 7.3 0.000 26.6 0.030 58.57 0.082 11.7 0.055 

0.029 67.9 0.094 75.3 0.123 69.98 0.000 41.1 0.075 49.8 0.023 101.65 0.003 37.6 0.000 

0.077 121.3 0.105 114.7 0.103 104.73 0.048 82.2 0.000 75.0 0.014 147.89 0.070 75.9 0.054 

0.129 177.3 0.113 156.5 0.037 142.15 0.047 104.6 0.062 101.3 0.127 195.51 0.185 117.7 0.000 

0.132 252.0 0.036 185.9 0.094 180.34 0.000 162.3 0.000 133.8 0.136 245.2 0.410 160.4 0.187 

0.106 330.7 0.113 215.3 0.117 220.16 0.008 191.0 0.113 167.1 0.191 295.06 0.687 195.5 0.255 

0.151 410.6 0.133 244.8 0.000 265.35 0.000 223.0 0.144 201.8 0.247 345.61 0.873 223.4 0.314 

0.179 502.3 0.146 283.0 0.190 302.31 0.226 249.5 0.224 237.1 0.348 396.55 1.081 251.5 0.397 

0.151 580.7 0.183 321.9 0.000 352.24 0.228 313.5 0.267 268.4 0.291 450.7 1.205 280.8 0.515 

0.400 661.3 0.357 360.3 0.005 393.18 0.209 346.3 0.499 303.3 0.484 502.46 1.383 301.7 0.62

0.317 753.8 0.351 398.5 0.170 436.99 0.400 376.9 0.349 339.5 0.414 558.59 1.603 329.6 0.890 

0.282 849.1 0.549 428.0 0.307 478.1 0.293 413.7 0.588 373.6 0.572 611.42 1.737 358.2 0.840 

0.510 933.7 0.504 461.1 0.383 524.44 0.615 442.0 0.539 408.4 0.550 666.75 1.966 385.1 1.068 

0.572 1027.1 0.608 491.9 0.198 579.19 0.354 483.1 0.754 444.5 0.699 719.31 2.181 412.9 1.177 

0.679 1118.3 0.595 525.1 0.316 626.43 0.603 514.3 0.785 484.3 0.759 783.71 2.430 436.0 1.454 

0.925 1205.5 0.914 550.2 0.096 684.65 0.957 531.6 1.061 518.3 0.938 844.04 2.648 467.4 1.422 

0.993 1298.1 0.986 579.7 0.535 719.86 0.393 557.8 1.178 556.7 1.031 908.45 3.077 494.3 1.924 

1.038 1401.5 1.067 610.5 0.503 775.72 0.405 596.2 1.302 597.4 1.196 969.29 3.393 526.0 2.060 

1.224 1487.9 1.222 639.1 0.698 817.41 0.255 636.9 1.521 629.2 1.325 1031.3 3.721 558.1 2.412 

1.391 1579.5 1.408 666.0 0.838 863.97 0.492 666.9 1.523 664.7 1.480 1092.6 4.118 601.7 2.438 

1.470 1676.7 1.508 695.2 0.811 919.98 0.393 708.9 2.014 687.7 1.712 1148.0 5.080 616.3 2.752 

1.672 1765.2 1.492 730.4 1.083 960.19 0.621 738.9 2.095 725.3 1.822 1209.9 5.853 628.7 2.670 

1.993 1837.7 1.637 767.7 0.986 1019.2 0.754 771.9 2.477 757.7 2.084 1262.0 6.494 645.6 3.143 

2.190 1922.1 1.724 807.2 1.345 1053.1 0.870 806.0 2.649 797.3 2.187 1323.6 7.048 664.5 3.564 

2.377 2007.9 1.859 853.5 1.701 1084.0 0.734 851.1 2.965 830.1 2.408 1376.9 7.382 694.0 4.029 

2.624 2085.3 2.113 892.9 2.065 1114.2 1.188 884.8 3.049 886.9 2.780 1484.7 7.765 720.3 4.38

2.856 2183.1 2.211 939.5 2.126 1167.1 1.410 950.1 3.459 925.5 3.012 1535.5 8.136 744.7 4.779 

3.230 2261.7 2.468 1030.3 2.238 1214.4 1.512 984.0 3.941 955.3 3.271 1591.7 8.448 769.9 5.284 

3.469 2354.8 2.819 1114.4 2.504 1250.6 1.817 1006.9 4.244 994.0 3.551 1638.2 8.910 783.8 5.840 

3.818 2430.1 3.205 1192.2 2.704 1290.7 1.838 1052.2 4.698 1021.5 3.855 1703.8 9.382 791.6 6.246 

4.464 2449.8 3.797 1283.5 3.086 1317.1 2.160 1081.2 5.015 1067.0 4.101 1773.5 9.843 796.7 6.777 

4.468 1355.9 3.400 1360.5 2.671 1211.9 5.630 1087.2 4.365 1862.1 10.251 803.5 7.077 

5.422 1421.3 3.878 1385.9 2.827 1260.2 6.267 1098.2 4.653 1944.3 10.563 817.1 7.732 

6.019 1517.8 4.237 1421.1 3.075 1306.8 6.616 1131.5 5.018 2013.0 8.285 

6.686 1592.7 4.437 1469.7 3.536 1420.0 7.133 1160.4 5.375 2097.0 8.513 

7.314 1663.4 5.049 1510.0 4.154 1668.4 7.759 1172.8 5.777 2171.4 8.994 

8.251 1707.6 5.230 1543.7 6.185 2255.1
B-29

Table B2. (Contd.) 

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm

KRB-01C 25°C KRB-06C 25°C KRB-04C 25°C KRB-05R 290°C

284°C 68000 h 284°C 68000 h Annealed - 284°C 68000 h

0.025 4.0 0.011 46.0 0.135 5.6 0.000 11.5

0.029 15.0 0.093 88.4 0.083 60.3 0.103 43.8

0.174 39.5 0.117 109.0 0.204 118.0 0.028 97.6

0.070 57.9 0.123 132.9 0.122 187.4 0.000 137.6

0.133 77.8 0.081 162.6 0.059 222.3 0.284 177.9

0.187 104.3 0.097 191.3 0.063 291.2 0.114 223.0

0.067 144.0 0.153 217.3 0.057 363.6 0.000 318.1

0.103 188.3 0.202 248.0 0.292 431.7 0.078 388.4

0.180 250.7 0.216 282.3 0.391 513.2 0.190 437.0

0.176 291.5 0.268 318.9 0.607 612.7 0.261 536.9

0.293 331.0 0.499 354.5 0.802 710.0 0.394 612.1

0.491 369.6 0.567 391.7 1.037 780.7 0.572 713.1

0.647 404.1 0.616 433.7 1.068 805.9 0.819 782.5

0.362 448.3 0.804 474.0 1.037 834.4 1.560 833.8

0.485 492.1 0.809 519.9 0.934 867.0 1.806 908.3

0.463 547.1 0.843 565.1 1.047 890.5 2.092 1006.6

0.655 600.8 0.909 609.7 1.336 903.1 2.736 1103.1

0.897 662.5 1.043 650.9 1.062 940.9 3.079 1187.7

1.172 715.0 1.011 697.3 1.106 969.6 3.216 1203.1

1.482 845.3 1.218 735.2 1.183 993.2 3.604 1198.1

1.788 899.7 1.444 874.4 1.346 1016.9 3.590 1224.2

1.926 958.5 1.425 922.0 1.490 1036.6 3.997 1257.4

2.192 1009.7 1.578 982.9 1.290 1074.7 4.414 1253.0

2.359 1068.7 1.791 1028.7 1.366 1101.1 4.676 1300.8

2.744 1119.8 1.945 1079.2 1.516 1119.9 5.060 1343.1

3.060 1148.5 2.027 1182.3 1.519 1146.4 5.638 1370.0

3.373 1273.7 2.400 1311.9 1.569 1172.5 5.865 1393.1

3.666 1352.5 2.427 1361.9 1.930 1301.3 6.404 1431.4

4.067 1425.5 2.734 1394.8 2.714 1592.9 6.987 1473.5

4.819 1456.1 3.088 1527.4 3.591 1815.4 7.099 1509.9

5.566 1441.5 3.407 1675.5 4.197 2047.5 7.773 1533.8

6.082 1470.0 3.541 1820.7 5.115 2262.4 9.105 1572.0

6.580 1511.2 3.863 1873.4 5.887 2451.7

4.152 1928.5 6.686 2602.9

4.586 2031.5

4.946 2062.8

5.631 2146.4
B-30

Table B2. (Contd.)

∆a 

(mm)

Jd

(kJ/m2)

∆a

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm

CF-8M Materials

205-25C 25°C 207-09C 290°C 207-10C 290°C 205-24C 290°C 758-02C 25°C 758-03C 25°C 758-01C 290°C 743-05

400°C 18000 h - - - - 400°C 18000 h 400°C 18000 h 400°C 18000 h 400°C 18000 h - 

0.000 30.6 0.000 6.7 0.077 56.8 0.100 9.93 0.017 30.3 0.070 29.2 0.000 4.3 0.08

0.095 69.5 0.000 94.1 0.043 72.5 0.121 15.66 0.000 52.9 0.000 45.9 0.070 7.7 0.09

0.052 103.7 0.000 109.2 0.185 101.8 0.040 25.88 0.176 95.6 0.145 76.1 0.050 36.1 0.08

0.149 156.4 0.000 160.7 0.108 134.4 0.063 38.77 0.352 124.5 0.303 115.4 0.113 66.8 0.09

0.271 215.5 0.040 207.6 0.219 184.2 0.063 53.93 0.429 147.0 0.431 159.2 0.049 83.4 0.155 

0.245 262.8 0.049 242.2 0.096 238.0 0.415 85.77 0.588 168.6 0.638 182.1 0.187 107.6 0.235 

0.475 329.6 0.000 349.2 0.128 256.7 0.082 101.93 0.844 190.0 0.727 204.2 0.235 140.4 0.322 

0.521 386.7 0.192 375.6 0.189 273.1 0.170 121.79 1.855 205.8 0.931 227.5 0.311 170.8 0.42

0.851 422.7 0.315 441.1 0.325 308.2 0.169 140.08 1.271 222.5 1.074 249.8 0.540 201.1 0.59

1.057 499.5 0.274 538.2 0.288 326.8 0.194 159.55 1.461 252.4 1.382 293.8 0.619 232.5 0.65

1.253 545.5 0.505 566.6 0.446 362.7 0.456 175.89 1.601 273.1 1.591 316.5 1.054 262.2 0.86

1.383 623.7 0.955 620.8 0.532 426.7 0.157 195.88 1.770 289.2 1.779 337.8 1.177 283.5 1.09

1.756 679.6 0.799 648.6 0.409 493.0 0.496 229.33 1.931 308.1 1.845 360.8 1.404 306.4 1.298 

2.068 739.7 1.023 725.2 0.756 503.7 0.828 263.53 2.114 328.0 2.124 381.4 1.513 331.9 1.763 

2.349 780.0 1.065 757.5 0.654 547.1 0.852 300.44 2.264 349.6 2.441 408.9 1.797 347.4 1.88

2.587 847.2 1.298 782.9 0.742 587.1 0.926 336.99 2.474 374.0 2.852 453.4 1.996 364.6 2.20

2.910 885.0 1.406 811.5 0.795 606.5 1.072 373.23 2.645 396.2 3.420 488.9 2.274 381.3 2.643 

3.175 954.3 1.543 839.7 0.942 622.6 1.394 387.14 3.075 423.9 3.868 522.1 2.469 398.3 3.04

3.304 978.1 1.867 856.8 1.022 663.0 1.577 421.74 3.576 463.6 4.008 524.2 2.734 415.8 3.778 

3.691 1,021.5 1.814 929.4 1.063 703.6 1.938 476.56 3.844 487.1 4.345 535.6 2.765 434.3 4.358 

4.621 1,133.4 2.068 972.7 1.333 735.8 2.027 494.86 4.413 524.9 4.778 548.0 3.223 450.4 4.88

4.938 1,201.3 2.077 1,015.3 1.565 790.4 2.294 531.68 4.607 542.7 5.422 557.4 3.296 470.2 5.698 

5.390 1,254.2 2.645 1,050.5 1.876 884.7 2.918 560.76 4.967 567.5 5.827 557.3 3.575 488.7 6.672 

5.632 1,279.6 3.154 1,167.7 2.210 910.8 3.146 580.29 5.281 598.5 6.415 556.7 3.908 503.6 7.84

6.413 1,356.3 3.312 1,239.9 2.702 1008.8 3.361 602.16 6.204 610.8 6.868 559.6 4.212 526.2 8.814 

6.752 1,375.1 4.287 1,262.9 3.242 1123.9 3.782 617.94 6.653 622.6 7.238 566.5 4.598 545.4 9.773 

7.127 1,408.8 4.854 1,369.9 4.019 1209.9 4.145 636.02 7.146 635.0 7.603 579.3 5.008 562.7 10.96

7.439 1,427.2 5.394 1,395.1 4.455 1230.3 4.812 680.97 7.995 626.1 7.818 583.6 5.395 586.9 11.70

7.768 1,438.0 5.792 1,493.8 4.590 1278.2 5.715 719.45 8.462 627.1 8.094 594.0 5.952 616.1 12.58

8.349 1,463.6 6.134 1,523.7 4.934 1309.3 5.969 746.85 8.961 631.3 8.352 603.2 6.325 632.3

8.676 1,500.1 6.634 1,531.6 5.854 1395.7 6.440 771.6 9.325 640.7 8.639 611.1 6.683 659.7

9.365 1,515.2 7.017 1,567.9 6.419 1448.6 7.042 789.41 9.704 648.5 9.004 621.8 7.456 706.4

9.629 1,524.8 7.900 1,597.0 7.211 1470.1 8.036 840.01 10.138 651.3 9.280 634.1 8.427 749.5

9.849 1,539.0 8.257 1,628.2 7.782 1510.6 9.043 873.14 10.486 656.0 9.751 659.6 9.339 762.7

10.170 1,549.2 9.254 1,605.6 8.895 1539.2 9.758 918.54 10.842 658.9 10.751 651.2 10.662 774.7

10.449 1,555.7 10.755 1,493.5 9.625 1560.6 10.251 925.28 11.575 639.2 11.896 773.3
B-31

Table B2. (Contd.)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm

743-03V 25°C 745-03V 25°C 747-03V 25°C 743-03B 25°C 744-02V 25°C 741-06T 25°C 742-05T 25°C 741-03

- - - - - - 320°C 50000 h 320°C 50000 h 350°C 2570 h 350°C 30000 h 400°

0.037 28.8 0.000 51.8 0.037 28.83 0.000 58.7 0.000 18.4 0.073 190.9 0.000 38.0 0.00

0.106 76.4 0.000 86.2 0.106 76.37 0.000 121.9 0.004 50.6 0.043 240.9 0.000 60.8 0.05

0.111 129.4 0.081 122.6 0.111 129.39 0.031 156.2 0.006 86.3 0.082 286.4 0.141 97.4 0.07

0.074 175.0 0.064 152.4 0.074 174.98 0.049 191.1 0.008 126.9 0.215 347.7 0.172 124.5 0.05

0.144 194.8 0.134 191.7 0.069 222.83 0.120 264.1 0.113 169.3 0.209 411.4 0.197 168.8 0.118 

0.069 222.8 0.274 230.3 0.215 275.67 0.196 301.6 0.329 211.6 0.274 472.7 0.317 215.1 0.174 

0.215 275.7 0.160 320.1 0.199 332.28 0.365 337.8 0.518 253.5 0.339 515.9 0.544 261.6 0.17

0.246 303.6 0.340 367.3 0.369 397.1 0.457 364.8 0.679 296.8 0.401 568.2 0.625 308.4 0.25

0.395 363.4 0.372 403.7 0.544 427.77 0.552 392.4 1.047 336.4 0.502 627.3 0.865 369.8 0.414 

0.369 397.1 0.512 444.6 0.699 493.31 0.676 450.4 1.787 366.4 0.582 688.6 1.134 400.7 0.544 

0.544 427.8 0.562 485.9 0.831 559.31 0.797 476.8 2.378 392.6 0.641 747.7 1.202 448.5 0.71

0.699 493.3 0.639 518.6 0.897 592.15 0.866 504.9 2.809 419.4 0.804 804.5 1.518 494.5 0.993 

0.710 527.3 0.701 586.6 1.003 624.32 1.061 530.8 3.272 447.1 0.931 861.4 1.773 537.8 1.12

0.831 559.3 0.831 625.3 1.172 652.89 1.195 556.6 3.630 475.9 1.086 927.3 1.912 584.6 1.474 

0.897 592.2 0.931 664.4 1.417 707.22 1.236 584.9 4.075 500.3 1.282 988.6 2.329 624.5 1.773 

1.003 624.3 1.124 709.5 1.543 735.61 1.442 639.4 4.353 528.6 1.418 1,047.7 2.709 658.4 2.05

1.172 652.9 1.247 756.1 1.739 767.63 1.639 662.4 4.594 558.0 1.617 1,143.3 3.166 698.4 2.54

1.417 707.2 1.442 799.4 1.881 795.14 1.711 688.9 4.915 591.1 1.898 1,237.5 3.815 729.8 3.14

1.739 767.6 1.625 842.6 2.170 818.01 1.958 710.6 5.252 622.5 2.247 1,324.7 4.313 776.0 3.82

1.881 795.1 1.881 890.2 2.424 869.61 1.932 739.5 5.614 666.1 2.969 1,436.7 4.972 838.0 4.664 

2.170 818.0 2.179 933.4 2.607 893.7 2.059 766.0 5.893 711.6 3.777 1,559.8 5.482 893.9 5.404 

2.424 869.6 2.541 970.2 2.789 916.55 2.369 832.6 6.201 753.3 4.181 1,673.0 6.182 956.6 6.07

2.607 893.7 3.033 1004.4 3.051 951.01 2.632 862.4 6.583 788.5 4.719 1,768.8 6.999 996.0 7.09

3.051 951.0 3.452 1038.7 3.283 985.26 2.877 886.7 7.123 808.0 5.138 1,899.1 7.820 1040.1 8.18

3.283 985.3 4.045 1078.4 3.819 1045.8 3.113 911.9 7.625 824.1 5.661 2,017.7 8.475 1088.1 9.015 

3.606 1013.3 4.610 1107.0 4.074 1091.5 3.465 930.7 8.436 810.4 6.229 2,193.3 9.251 1113.6 10.15

4.074 1091.5 5.070 1142.3 4.389 1132.2 3.710 950.1 8.905 815.1 7.110 2,339.8 9.912 1140.6 11.14

4.389 1132.2 5.554 1175.5 4.684 1171.1 4.163 978.7 9.256 830.5 7.723 2,486.8 10.607 1155.1 12.33

4.684 1171.2 6.009 1204.6 5.018 1204.3 4.914 1087.8 9.573 848.1 8.947 2,666.8 11.413 1144.6

5.018 1204.4 6.495 1228.3 5.364 1234.2 5.720 1163.7 9.993 2,835.7

5.364 1234.2 7.089 1251.0 5.885 1259.3 6.108 1202.3 10.814 2,988.0

5.885 1259.3 7.775 1253.5 6.215 1298.1 6.740 1228.0 11.904 3,174.0

6.215 1298.2 8.357 1259.7 6.613 1328.6 7.308 1250.5 12.533 3,372.2

6.613 1328.7 8.860 1270.7 6.893 1367.3 7.969 1256.6

6.893 1367.4 9.366 1276.9 7.240 1398.2 8.542 1266.1

7.240 1398.3 9.894 1275.0 7.562 1426.9 9.084 1289.6

7.562 1426.9 10.425 1267.6 9.687 1303.1
B-32

Table B2. (Contd.)

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm)

Jm

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm

741-03T 25°C 741-05B 25°C 743-08T 290°C 74x-xxx 290°C 741-05T 290°C 741-02T 290°C 741-04T 290°C 752-08

450°C 2570 h 450°C 2570 h - - 320°C 50000 h 400°C 2570 h 400°C 10000 h 450°C 3000 h - 

0.073 50.1 0.026 25.0 0.044 127.3 0.037 28.8 0.000 36.7 0.000 11.0 0.117 18.8 0 

0.043 143.3 0.110 4.7 0.252 216.9 0.106 76.4 0.050 84.6 0.030 29.9 0.174 31.4 0.009

0.178 193.5 0.043 75.1 0.329 367.8 0.111 129.4 0.000 109.1 0.000 67.9 0.000 52.9 0.012

0.290 239.1 0.108 116.1 0.516 315.8 0.074 175.0 0.068 133.1 0.194 92.2 0.261 81.0 0.086

0.328 298.2 0.134 163.8 0.681 386.5 0.144 194.8 0.000 157.7 0.000 117.4 0.239 103.3 0.111

0.517 350.8 0.246 216.3 1.043 452.3 0.069 222.8 0.100 197.1 0.276 150.3 0.457 126.1 0.171

0.612 407.7 0.391 282.4 1.207 532.4 0.215 275.7 0.195 260.2 0.186 183.8 0.436 150.3 0.229

0.735 467.0 0.424 271.1 1.526 546.5 0.246 303.6 0.338 294.3 0.415 218.6 0.668 174.6 0.087

0.966 517.4 0.651 326.0 1.669 654.9 0.395 363.4 0.540 325.5 0.575 253.4 0.648 200.1 0.290

1.223 579.1 0.873 380.9 1.789 621.8 0.369 397.1 0.610 352.2 0.749 288.3 0.973 224.0 0.234 

1.541 643.9 1.080 440.3 2.097 692.4 0.544 427.8 0.799 377.9 0.878 324.6 1.034 248.8 0.215

1.898 701.4 1.406 495.3 2.459 753.6 0.699 493.3 0.669 408.2 0.976 361.5 1.336 271.9 0.343

2.515 783.8 1.686 555.6 2.931 805.2 0.710 527.3 1.124 429.2 1.261 394.0 1.498 295.8 0.403

4.658 1,054.7 2.148 637.5 3.414 880.5 0.831 559.3 1.008 458.4 1.416 429.1 1.651 319.8 0.345

5.248 1,173.2 2.708 726.8 3.996 950.9 0.897 592.2 1.317 481.8 1.732 460.5 1.930 341.8 0.518

6.296 1,297.1 3.168 812.4 4.775 1,002.5 1.003 624.3 1.276 511.3 1.949 492.9 2.186 362.9 0.619

7.300 1,404.0 4.113 942.0 5.247 1,030.5 1.172 652.9 1.680 558.6 2.197 524.7 2.674 390.8 0.707

8.141 1,522.4 5.072 1,082.8 6.081 1,124.5 1.417 707.2 2.022 607.7 2.527 552.6 2.778 406.9 0.729

9.218 1,646.3 5.957 1,201.2 6.981 1,199.5 1.739 767.6 2.231 630.4 2.928 576.9 3.198 429.9 0.917

10.843 1,747.3 6.768 1,359.0 7.453 1,241.8 1.881 795.1 2.496 650.4 3.153 609.1 3.435 453.6 1.018

12.083 1,837.3 7.949 1,494.2 8.211 1,331.0 2.170 818.0 2.618 674.5 3.593 629.1 4.000 480.1 1.254 

13.102 1,910.3 9.071 1,629.4 2.424 869.6 2.998 704.6 3.804 662.3 4.338 506.1 1.321

10.414 1,781.4 2.607 893.7 3.242 737.6 4.270 696.3 4.953 533.9 1.408

11.638 1,956.1 3.051 951.0 3.527 768.6 4.727 726.1 5.550 557.4 1.536

12.879 2,068.6 3.283 985.3 3.844 796.4 5.239 758.1 5.972 585.4 1.665

3.606 1013.3 4.287 831.3 5.926 776.2 6.860 603.1 1.978

4.074 1091.5 4.748 862.0 6.477 797.6 7.590 617.7 2.378

4.389 1132.2 5.210 890.9 7.043 829.0 8.453 620.5 3.066

4.684 1171.2 5.724 912.7 7.698 850.6 9.165 626.2 3.927

5.018 1204.4 6.142 937.9 8.211 876.7 9.849 629.6 5.357

5.364 1234.2 6.443 984.7 8.740 899.5 10.448 633.6 6.277

5.885 1259.3 6.981 1010.8 9.262 918.4 7.462

6.215 1298.2 7.798 1018.8 9.896 922.6 8.711

6.613 1328.7 8.200 1053.6 10.312 939.2 9.876

6.893 1367.4 8.808 1071.0 10.79

7.240 1398.3 9.272 1095.2

7.562 1426.9 10.183 1134.8
B-33

Table B2. (Contd.)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm

751-07T 25°C 752-06T 25°C 753-02T 25°C 752-05V 25°C 75-02T 25°C 752-04T 25°C 751-06V 25°C 751-03

290°C 30000 h 320°C 30000 h 320°C 50000 h 320°C 50000 h 350°C 10000 h 350°C 30000 h 350°C 30000 h 400°

0.000 43.0 0.000 31.9 0.000 16.2 0.000 21.9 0.054 56.6 0.000 23.19 0.000 18.4 0.000 

0.011 86.5 0.000 69.3 0.000 46.4 0.000 85.6 0.011 91.0 0.045 39.62 0.045 42.3 0.000 

0.000 111.7 0.057 101.8 0.163 72.5 0.015 115.0 0.048 134.2 0.117 72.38 0.111 61.0 0.037 

0.057 139.0 0.100 133.5 0.035 98.7 0.113 145.0 0.167 146.0 0.168 93.05 0.245 81.1 0.017 

0.014 169.1 0.075 172.0 0.000 127.9 0.197 176.3 0.261 174.2 0.297 113.97 0.277 108.2 0.067 

0.134 202.1 0.202 212.7 0.380 156.3 0.298 207.8 0.264 209.2 0.563 136.08 0.468 124.4 0.175 

0.106 241.0 0.194 254.0 0.102 185.1 0.383 239.4 0.285 254.4 0.593 158.9 0.667 145.6 0.28

0.259 279.1 0.399 297.9 0.348 217.0 0.484 261.4 0.339 284.4 0.862 182.95 1.008 167.3 0.399 

0.198 317.6 0.471 335.8 0.450 246.7 0.583 294.0 0.372 323.3 1.209 204.08 1.183 186.3 0.608 

0.266 367.9 0.547 379.9 0.384 280.8 0.745 314.8 0.669 357.1 1.492 224.7 1.689 208.7 0.679 

0.345 417.9 0.840 419.1 0.694 309.9 0.841 335.6 0.810 399.8 1.763 245.47 2.006 224.1 0.94

0.438 467.0 0.787 463.3 0.878 338.8 0.998 355.8 0.936 466.5 2.162 267 2.580 241.0 1.255 

0.467 540.4 1.003 508.1 1.105 368.1 1.155 375.2 1.181 492.0 2.495 284.95 3.051 258.2 1.302 

0.653 600.5 1.217 546.4 1.350 396.3 1.268 394.6 1.290 543.9 2.842 304.49 3.420 277.8 1.530 

0.713 663.2 1.475 584.4 1.590 423.5 1.505 413.0 1.301 571.0 3.372 324.33 4.058 295.5 1.909 

0.988 719.3 1.608 622.7 2.128 444.6 1.592 432.0 1.524 594.2 3.920 340.49 4.754 316.2 2.062 

1.100 777.8 1.740 665.4 2.125 474.0 1.756 451.0 1.579 619.1 4.386 359.56 5.442 333.9 2.320 

1.380 886.2 2.062 700.8 2.525 499.9 1.942 469.5 1.702 646.9 4.846 383.55 6.199 346.0 2.64

1.593 941.6 2.371 730.9 2.629 526.8 2.127 486.0 2.013 699.4 5.220 407.19 6.991 363.0 3.085 

1.785 996.9 2.580 768.3 2.895 552.8 2.346 503.0 2.113 727.5 5.718 427.33 7.591 380.0 3.605 

1.927 1055.0 2.920 836.9 3.526 580.6 2.613 527.0 2.563 772.5 6.265 451.1 8.291 403.7 4.173 

2.184 1106.3 3.566 882.7 3.874 613.0 3.069 544.3 2.995 793.4 6.760 472.38 8.861 438.7 5.082 

2.384 1157.4 4.291 913.2 4.649 629.6 3.470 559.4 3.185 819.0 7.103 497.58 9.590 469.0 5.893 

2.745 1208.7 5.077 943.0 4.967 656.8 3.795 576.6 3.748 842.6 7.374 525.17 10.711 479.6 6.817 

3.113 1267.9 5.607 981.8 5.630 672.6 4.434 613.8 3.976 857.5 7.669 560.22 11.499 495.2 7.72

3.452 1338.2 6.598 1007.8 5.896 699.3 4.777 635.9 4.499 897.7 8.037 591.45 8.812 

3.882 1409.6 7.567 1015.3 6.366 720.6 5.096 658.2 4.639 910.2 8.522 619.65 9.349 

4.318 1473.3 8.795 989.3 6.529 751.1 5.392 680.7 6.296 951.2 8.987 643.02 9.84

4.884 1540.6 9.619 1000.3 7.147 774.5 5.855 714.9 6.715 954.5 9.675 647.2 10.85

5.335 1611.0 10.187 1031.1 7.545 803.5 6.403 739.8 7.116 963.8 10.098 658.92 11.54

5.758 1703.0 10.610 1074.4 8.301 818.3 7.121 748.4 7.635 997.6 10.650 668.61

6.349 1766.1 8.759 845.0 7.911 746.2 8.879 1025.5 11.054 681.05

7.089 1814.9 9.507 848.2 8.448 768.8 9.725 1046.3

7.942 1825.6 9.996 863.3 8.996 791.7 10.344 1067.1

8.859 1810.4 9.960 781.2 10.798 1099.1

9.593 1793.6 10.693 770.0 11.403 1134.1

10.197 1778.1 11.903 1168.3
B-34

Table B2. (Contd.)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm

751-01T 25°C 751-03V 25°C 753-06B 25°C 751-04T 25°C 752-08B 290°C 753-03V 290°C 753-05B 290°C 752-07

400°C 10000 h 400°C 10000 h 400°C 10000 h 450°C 2570 h - - - - Annealed - 320°

0.000 16.12 0.000 9.3 0.014 21.0 0.000 11.4 0.000 17.7 0.031 18.9 0.000 31.7 0.000 

0.074 45.26 0.066 18.4 0.018 63.4 0.034 24.4 0.004 36.6 0.000 83.1 0.014 79.2 0.027 

0.153 90.09 0.097 29.7 0.046 106.6 0.000 40.9 0.015 73.5 0.126 154.8 0.089 112.1 0.059 

0.414 129.81 0.045 39.8 0.129 154.4 0.142 56.3 0.000 96.0 0.164 192.2 0.254 180.8 0.294 

0.501 146.14 0.050 55.6 0.348 204.3 0.119 72.3 0.000 123.0 0.080 210.6 0.270 217.0 0.338 

0.511 161.56 0.146 82.1 0.700 233.7 0.105 92.6 0.000 176.5 0.000 252.9 0.294 254.2 0.505 

0.668 187.52 0.162 102.9 0.817 249.7 0.109 113.6 0.113 204.1 0.137 272.7 0.341 292.3 0.506 

0.863 217.34 0.159 127.4 1.031 279.9 0.236 137.5 0.222 230.5 0.235 311.7 0.487 329.4 0.947 

1.078 252.14 0.288 153.3 1.342 307.3 0.295 161.7 0.052 253.6 0.173 332.2 0.516 368.6 1.14

1.208 267.63 0.388 179.2 1.517 335.1 0.269 196.3 0.126 275.4 0.236 374.6 0.619 407.6 1.334 

1.477 283.22 0.539 207.7 1.841 361.8 0.426 225.2 0.192 297.3 0.418 414.4 0.764 446.5 1.88

1.572 298.92 0.533 237.1 2.182 387.0 0.557 254.4 0.162 320.1 0.140 462.2 0.879 485.2 1.912 

1.856 319.16 0.759 267.9 2.488 411.0 0.746 283.7 0.162 343.1 0.634 473.3 1.061 523.2 2.256 

2.113 334.31 0.887 296.8 2.780 435.1 0.847 314.3 0.302 367.3 0.287 501.9 1.158 561.9 2.449 

2.453 351.02 0.994 327.0 3.064 457.3 0.951 349.4 0.406 385.2 0.567 536.8 1.281 601.4 2.90

2.640 364.11 1.338 357.5 3.345 491.5 1.198 387.1 0.278 407.3 0.810 576.6 1.495 637.5 3.107 

2.784 380.68 1.636 384.1 3.744 523.0 1.477 424.5 0.615 423.7 1.041 621.4 1.557 678.0 3.663 

3.011 400.37 2.095 418.3 4.245 544.2 1.924 470.4 0.595 442.7 1.161 662.5 1.779 715.3 3.913 

3.229 419.57 2.459 450.0 4.613 566.9 2.143 504.5 0.721 481.5 1.686 717.8 2.079 808.2 4.722 

3.516 435.85 3.304 494.1 5.032 587.5 2.542 538.3 0.633 504.5 1.886 761.0 2.112 849.6 5.230 

3.830 454.31 3.930 520.8 5.360 610.6 2.869 569.1 0.920 520.8 2.093 778.0 2.369 882.6 5.61

4.278 472.09 4.804 542.2 5.961 632.5 3.379 605.6 0.703 547.6 2.131 838.1 2.449 921.2 6.239 

4.571 487.03 5.490 568.4 6.636 642.1 3.756 639.7 0.934 589.6 2.630 888.4 2.714 954.2 6.726 

5.377 498.36 6.102 594.1 7.182 661.1 4.315 669.4 1.148 610.2 3.527 924.3 2.908 991.1 7.616 

5.853 503.19 6.606 624.1 7.885 670.8 5.013 693.9 1.274 659.3 4.097 984.6 3.300 1023.8 8.239 

6.280 511.19 7.524 650.8 8.546 683.4 5.637 715.7 1.458 705.2 4.631 1063.8 3.794 1090.4 8.727 

6.583 520.53 8.240 673.5 9.336 682.9 6.137 741.7 1.773 754.2 4.975 1106.6 4.164 1128.6 9.326 

6.884 533.46 8.788 699.6 10.103 683.8 6.971 757.5 2.021 775.7 5.616 1116.4 4.532 1184.8 9.839 

7.481 536.11 9.639 704.3 7.779 764.1 2.433 824.9 5.767 1162.6 5.087 1222.9 10.43

7.861 535.41 10.356 708.0 8.513 773.6 2.987 871.8 6.194 1185.7 5.630 1254.1

8.584 550.54 11.026 717.2 9.370 772.7 3.676 950.3 6.956 1230.7 6.137 1285.7

9.058 549.92 10.099 769.1 4.714 1073.9 7.352 1248.4 6.861 1369.4

9.645 557.94 10.853 760.7 5.880 1173.6 8.323 1255.8 7.390 1387.2

9.870 563.51 6.938 1219.0 7.782 1414.6

10.361 574.87 7.836 1265.0 8.661 1452.9

10.852 594.49 9.408 1421.3

11.388 598.15 10.292 1449.5
B-35

Table B2. (Contd.)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm)

Jd

(kJ/m2)

∆a 

(mm

752-05T 290°C 751-05T 290°C 751-02T 290°C 751-02V 290°C 751-03T 290°C

350°C 30000 h 400°C 2570 h 400°C 10000 h 400°C 10000 h 450°C 2570 h

0.083 16.6 0.017 13.7 0.229 17.7 0.000 14.4 0.000 14.6

0.066 48.7 0.000 50.7 0.075 62.9 0.000 49.0 0.000 55.3

0.241 67.6 0.231 83.6 0.264 91.2 0.000 74.8 0.119 86.1

0.191 86.6 0.018 119.2 0.137 116.2 0.000 102.0 0.172 120.4

0.360 107.3 0.295 157.1 0.443 143.1 0.011 130.8 0.603 156.7

0.286 128.5 0.522 194.4 0.218 155.3 0.096 160.5 0.580 186.0

0.506 158.5 0.595 226.1 0.525 184.1 0.049 192.0 0.944 216.4

0.491 188.8 0.807 257.6 0.500 212.0 0.088 225.3 1.132 245.9

0.792 219.1 0.894 290.8 0.841 240.1 0.285 253.9 1.342 276.7

0.930 248.2 1.152 322.4 0.763 269.1 0.441 282.1 1.613 305.6

1.210 278.5 1.227 355.2 1.277 295.4 0.694 309.3 1.821 335.0

1.132 310.7 1.551 387.3 1.342 321.8 0.733 338.5 2.567 354.7

1.485 342.1 1.881 412.9 1.833 346.1 0.988 366.7 3.083 373.3

1.656 371.1 2.122 441.8 1.976 375.0 1.341 393.4 3.914 394.0

1.968 397.1 2.495 467.5 2.488 400.1 1.511 419.2 4.288 418.4

2.249 424.3 2.742 493.6 2.567 429.0 1.807 443.3 5.261 437.7

2.595 448.2 3.139 517.0 3.121 451.5 1.971 468.4 5.772 458.7

2.872 473.6 3.418 548.1 3.397 482.4 2.449 499.3 6.589 473.6

3.188 496.7 3.814 570.0 3.828 511.7 2.786 522.6 7.239 486.6

3.844 517.7 4.332 599.7 4.327 535.0 3.144 543.8 8.075 493.4

4.284 548.6 4.929 632.6 4.809 555.8 3.478 572.3 8.635 505.3

4.952 577.9 5.645 662.0 5.341 580.2 3.917 596.4 9.325 522.6

5.634 610.1 6.191 693.5 5.901 600.3 4.569 617.6 10.060 533.7

6.299 636.7 6.911 713.4 6.490 617.9 5.004 642.1

7.003 657.7 7.472 735.5 7.170 641.0 5.447 666.8

7.628 676.1 8.200 746.7 7.995 652.1 6.212 688.0

8.326 686.6 8.734 763.2 8.698 661.4 6.931 703.7

8.936 702.7 9.258 778.7 9.260 676.0 7.585 718.1

9.421 712.7 9.789 791.1 9.808 690.6 8.073 739.4

10.013 718.7 10.228 806.0 10.400 695.9 8.550 759.2

8.988 779.0

9.374 800.4

9.853 811.8

10.335 818.5
B-36

Table B3. Results from fracture toughness J-R curves conducted at MEA on seven heats of CASS materials.

Specimen 

ID

Heat Orientation Test Temp. 

(°C)

Deformation J Modified J Flow Stress 

(MPa)

JIc (kJ/m2) C n JIc (kJ/m2) C n

I1S-03 I C-L 25 508.4 781.5 0.637 498.0 796.0 0.682 411.2 

I1S-01 I L-C 25 624.0 861.5 0.591 639.4 896.5 0.638 411.2 

I2S-01 I L-C 25 544.7 811.6 0.630 551.3 840.7 0.675 411.2 

I1S-06 I C-L 25 497.8 741.1 0.522 476.8 771.1 0.611 466.8 

I1S-04 I L-C 25 455.7 705.8 0.539 409.7 733.9 0.671 466.8 

I2S-03 I L-C 25 408.3 684.2 0.593 408.6 710.1 0.635 466.8 

I1S-02 I L-C 290 386.2 512.6 0.459 364.5 534.3 0.586 284.2 

I2S-02 I L-C 290 397.2 536.9 0.503 406.6 557.0 0.539 284.2 

I1S-05 I L-C 290 250.1 385.5 0.480 223.4 402.2 0.614 303.7 

I2S-04 I L-C 290 274.6 425.0 0.512 266.3 443.2 0.586 303.7 

P2B-03 P2 C-L 25 1,304.2 1,250.6 0.773 1,335.2 1,256.5 0.828 381.0 

P2B-01 P2 L-C 25 1,289.0 1,241.6 0.837 1,240.6 1,225.2 0.896 381.0 

P2T-01 P2 L-C 25 1,365.5 1,274.3 0.754 1,569.5 1,315.3 0.854 381.0 

P2T-06 P2 L-C 25 950.3 1,178.3 0.796 1,041.5 1,236.9 0.853 421.7 

P2B-07 P2 L-C 25 1,340.2 1,346.2 0.821 1,533.2 1,400.0 0.879 421.7 

P2T-08 P2 L-C 25 1,035.9 1,221.9 0.711 1,086.7 1,261.8 0.762 436.8 

P2T-10 P2 L-C 25 1,456.6 1,426.5 0.630 1,602.7 1,487.1 0.675 436.8 

P2B-06 P2 L-C 25 747.1 1,053.6 0.765 888.8 1,097.5 0.645 426.4 

P2T-04 P2 L-C 25 559.0 867.3 0.687 567.3 901.9 0.736 426.4 

P2B-02 P2 L-C 290 1,483.6 1,080.9 0.691 1,749.1 1,102.3 0.765 268.5 

P2T-02 P2 L-C 290 892.3 873.7 0.694 949.8 891.5 0.782 268.5 

P2T-07 P2 L-C 290 1,050.3 980.8 0.650 1,124.4 1,004.8 0.696 288.2 

P2T-09 P2 L-C 290 1,017.2 964.9 0.635 1,147.4 1,013.5 0.680 286.8 

P2T-05 P2 L-C 290 874.6 893.1 0.484 916.9 920.0 0.590 288.6 

692-08B 69 H-H 25 204.3 405.4 0.597 202.2 421.6 0.638 435.5 

692-08T 69 H-H 25 322.1 552.9 0.566 320.1 571.9 0.606 435.5 

691-04B 69 H-H 25 702.9 888.8 0.425 686.2 925.5 0.527 467.7 

691-03B 69 H-H 25 455.0 614.2 0.368 368.3 639.4 0.596 469.1 

691-05B 69 H-H 25 495.0 661.4 0.375 448.1 690.3 0.522 472.7 

693-07T 69 H-H 290 700.1 756.3 0.312 701.8 785.8 0.460 301.4 

693-01V 69 V-H 290 266.2 424.8 0.540 252.4 439.5 0.621 301.4 

691-06T 69 H-H 290 450.9 523.7 0.259 408.3 550.0 0.465 312.2 

691-05T 69 H-H 290 255.1 368.5 0.412 232.6 384.7 0.536 304.4 

691-03T 69 H-H 290 261.8 376.0 0.395 254.2 392.3 0.466 327.6 
B-37

Table B3. (Contd.)

Specimen 

ID

Heat Orientation Test Temp. 

(°C)

Deformation J Modified J Flow Stress 

(MPa)

JIc (kJ/m2) C n JIc (kJ/m2) C n

C1B-03 C1 C-L 25 347.3 549.0 0.564 349.8 569.8 0.604 356.2 

C1B-01 C1 L-C 25 291.9 404.6 0.361 276.3 422.5 0.456 356.2 

C1B-02 C1 L-C 25 220.4 416.5 0.614 217.3 431.3 0.658 356.2 

C1B-04 C1 L-C 290 - - - 238.0 384.5 0.595 241.1 

C1B-05 C1 L-C 290 236.5 362.4 0.527 221.6 380.3 0.639 241.4 

P1B-03 PI C-L 25 605.9 866.5 0.629 617.2 898.0 0.673 413.8 

P1B-01 PI L-C 25 499.8 776.1 0.635 502.6 803.4 0.680 416.5 

P1T-01 PI L-C 25 734.3 1,017.4 0.733 740.6 1,045.3 0.785 416.5 

P1T-08 PI C-L 25 210.3 526.3 0.804 202.0 546.4 0.861 439.8 

P1B-06 PI L-C 25 716.8 945.8 0.527 737.7 982.0 0.565 458.1 

P1T-06 PI L-C 25 521.3 837.6 0.654 521.6 866.5 0.701 458.1 

P1B-05 PI L-C 25 242.8 445.0 0.541 241.2 462.2 0.579 481.8 

P1T-04 PI L-C 25 203.7 368.0 0.499 203.0 382.7 0.535 481.8 

PIB-02 PI L-C 290 554.5 664.1 0.448 557.8 691.7 0.540 295.8 

PIT-02 PI L-C 290 630.6 733.8 0.488 646.2 771.2 0.604 295.8 

PIB-07 PI L-C 290 400.7 529.9 0.424 389.2 559.7 0.537 315.8 

PIT-07 PI L-C 290 542.3 663.3 0.435 526.4 691.7 0.565 315.8 

PIT-05 PI L-C 290 293.7 451.7 0.505 298.6 470.0 0.599 324.2 

683-05B 68 H-H 25 334.4 552.8 0.562 334.4 572.9 0.602 400.2 

683-05T 68 H-H 25 282.6 485.5 0.554 243.2 504.1 0.698 400.2 

683-03V 68 V-H 25 312.1 526.0 0.562 294.7 546.3 0.645 400.2 

681-04B 68 H-H 25 798.0 1,037.7 0.608 832.0 1,075.5 0.636 444.3 

681-03B 68 H-H 25 408.4 648.6 0.531 412.6 673.6 0.672 467.8 

681-04T 68 H-H 25 294.5 467.7 0.448 283.1 486.1 0.515 471.7 

681-05B 68 H-H 25 293.0 532.9 0.578 290.1 551.9 0.619 471.7 

683-07T 68 H-H 290 753.4 783.0 0.271 740.5 795.3 0.459 282.2 

681-06T 68 H-H 290 446.1 592.8 0.475 459.4 617.0 0.509 318.8 

681-05T 68 H-H 290 335.3 464.9 0.431 323.4 487.9 0.528 312.2 

681-03T 68 H-H 290 312.5 454.9 0.446 316.6 475.1 0.486 338.5 

743-05B 74 H-H 25 610.3 795.4 0.481 573.4 826.1 0.618 405.1 

743-05T 74 H-H 25 577.1 710.6 0.355 584.4 746.0 0.422 405.1 

741-06T 74 H-H 25 692.1 852.6 0.439 725.0 895.6 0.476 410.5 

741-03B 74 H-H 25 389.0 556.5 0.420 374.0 578.7 0.500 429.6 

741-03T 74 H-H 25 238.8 404.0 0.483 210.2 418.0 0.603 438.5 

741-05B 74 H-H 25 312.9 502.9 0.488 308.6 514.8 0.523 438.5 

C-1

APPENDIX C: EXPERIMENTAL AND ESTIMATED 

CHARPY-IMPACT DATA FOR AGED CASS MATERIALS

The RT Charpy-impact energy of a specific heat of CASS materials as a function of aging time 

and temperature can be obtained from the estimated saturation RT Charpy-impact energy, 

CVsat, and the kinetics of embrittlement. The value of CVsat is estimated from Eqs. 18–26 

described in Section 2.4.1 of the report and the kinetics of embrittlement are estimated from 

Eqs. 11–17 described in Section 2.3 of the report. Information regarding the initial RT Charpyimpact energy of the unaged material and the aging time and temperature is needed for these 

estimations. The RT Charpy-impact energy for a specific time and temperature condition is 

estimated in three steps. First, the aging time and temperature are converted to an equivalent 

value of Parameter P. Next, the tanh function of the term [(P – θ)/α] is determined; two sets of 

tanh function values are obtained, one using the experimental value of θ and the second with an 

assumed value of 2.9 for θ. The CV for the specific time and temperature is then calculated 

from Eq. 13 from Section 2.3 of the report. A single value of θ is assumed in this report. 

However, the existing data suggests that θ varies with the material composition. 

A comparison of the estimated and experimental values of RT Charpy-impact energy for several 

heats of CF-3, CF-8, and CF-8M CASS materials are shown in Figs. C1 and C2. These figures 

are an updated version of Figs. 19 and 20 of NUREG/CR-4513 Rev. 1. The solid and dash 

lines represent the estimated values using, respectively, the experimental value or assumed 

value of θ. 

The results indicate that the estimated values of RT CVsat are either accurate or slightly 

conservative for all grades and heats of CASS materials. The two exceptions are the static cast 

CF-3 Heat 47 and static cast CF-3M Heat FD. For these two heats, the estimated values are 

significantly higher than the experimental values. The reason for such a large difference for two 

heats out of more than 130 heats of materials is not known. The results also indicate that the 

estimates of the change in RT Charpy-impact energy for materials aged at low-temperature (i.e., 

290-320°C) are in good agreement with the experimental values for most materials and are 

conservative for a few. The only exception is static cast CF-8M Heat 75. The estimates for high 

temperature (i.e., 350-400°C) aged materials show good agreement for most of the materials 

and are quite conservative for the rest. The exceptions are static cast CF-3 Heat 47 and the 

EPRI heat, centrifugally cast CF-8 Heat P1 and CF-8M heat P4, and the static cast CF-8M 

Heat FB. As discussed earlier, the agreement between the estimated and experimental values 

of RT Charpy-impact energy can be further improved by using a θ value that varies with the 

material composition and ferrite content, and activation energy for thermal embrittlement that 

varies with aging temperature. 
C-2

Figure C1. RT Charpy–impact energy for 16 ANL heats and 1 EPRI heat, observed experimentally (solid lines) 

(dashed lines) from the composition and initial impact energy of the materials aged at 290–400°C. 
C-3

Figure C1. (Contd.) 
C-4

Figure C1. (Contd.) 
C-5

Figure C1. (Contd.) 
C-6

Figure C1. (Contd.) 
C-7

Figure C2. RT Charpy–impact energy for the GF, FRA and EdF heats, observed experimentally (solid lines) an

lines) from the composition and initial impact energy of the materials aged at 300–400°C. 
C-8

Figure C2. (Contd.) 
C-9

Figure C2. (Contd.) 

D-1

APPENDIX D: REFERENCES

The source of the experimental data on Charpy-impact, tensile, and fracture toughness 

properties of unaged and aged but non-irradiated CASS materials are listed below according to 

the organization/institution where it was obtained. 

Argonne National Laboratory, Argonne, IL, USA

A1. Chopra, O.K., and A. Sather, Initial Assessment of the Mechanisms and Significance of 

Low-Temperature Embrittlement of Cast Stainless Steels in LWR Systems, NUREG/CR5385, ANL-89/17, August 1990. 

A2. Chopra, O.K., A. Sather, and L.Y. Bush, "Long Term Embrittlement of Cast Stainless 

Steels in LWR Systems: Semiannual Report, April-September 1989," NUREG/CR-4744, 

Vol. 4, No. 2, ANL-90/49, June 1991.

A3. Chopra, O.K., "Long-Term Embrittlement of Cast Duplex Stainless Steels in LWR 

Systems, Semiannual Report Oct. 1990 – March 1991, NUREG/CR-4744, Vol. 6, No. 1, 

ANL-91/22, August 1992.

A4. Chopra, O.K., "Long-Term Embrittlement of Cast Duplex Stainless Steels in LWR 

Systems, Semiannual Report Oct. 1991 – March 1992, NUREG/CR-4744, Vol. 7, No. 1, 

ANL-92/42, May 1993.

A5. Chopra, O.K., “Estimation of Fracture Toughness of Cast Stainless Steels during Thermal 

Aging in LWR Systems,” NUREG/CR-4513, Rev. 1, ANL-93/22, August 1994. 

A6. Michaud, W.F., P.T. Toben, W.K. Soppet, and O.K. Chopra, “Tensile-Property 

Characterization of Thermally Aged Cast Stainless Steels,” NUREG/CR-6142, ANL-93/35, 

February 1994. 

A7. Chopra, O.K. and W.J. Shack, “Mechanical Properties of Thermally Aged Cast Stainless 

Steels from Shippingport Reactor Components,” NUREG/CR-6275, ANL-94/37, April 

1995.

Central Electricity Generating Board, UK (The British Electricity Industry 1957-1990)

A8. Pumphrey, P.H., and K.N. Akhurst, “Aging Kinetics of CF3 Cast Stainless Steel in 

Temperature Range 300-400°C,” Mater. Sci. Technol. 6, 211–219, 1990.

Electricité de France (EdF), France

A9. Bonnet, S., J. Bourgoin, J. Champredonde, D. Guttmann, and M. Guttmann, “Relationship 

between Evolution of Mechanical Properties of Various Cast Duplex Stainless Steels and 

Metallurgical and Aging Parameters: An Outline of Current EDF Programmes,” Mater. Sci. 

Technol. 6, 221–229, 1990.

A10. Jayet-Gendrot, S., P. Ould, and T. Meylogan, "Fracture Toughness Assessment of InService Aged Primary Circuit Elbows Using Mini-CT Specimens Taken from Outer Skin," 

Nucl. Eng. and Design 184, 3–11, 1998. 
D-2

A11. Jayet-Gendrot, S., P. Ould, and P. Balladon, "Effect of Fabrication and Test Parameters 

on the Fracture Toughness of Aged Cast Duplex Stainless Steels," Fontevaraud III, Vol. 1, 

pp. 90–97, French Nuclear Energy Society, 1994.

A12. Le Delliou, P., G. Bezdikian, P. Ould, and N. Safa, "Full-Scale Test on an Aged Cast 

Duplex Stainless Steel Lateral Connection: Results and Analysis," PVP2006-IVPVT-11-

94005, in Proc. of 2006 ASME Pressure Vessel and Piping Conf., July 23–27, 2006, 

Vancouver, BC, Canada, 2006.

Electric Power Research Institute 

A13. McConnell, P., and J.W. Sheckherd, “Fracture Toughness Characterization of Thermally 

Embrittled Cast Duplex Stainless Steel, Report NP-5439, Electric Power Research 

Institute, Palo Alto, CA, September 1987.

Framatome, 

A14. Meyzaud, Y., P. Ould, P. Balladon, M. Bethmont, and P. Soulat, “Tearing Resistance of 

Aged Cast Austenitic Stainless Steel,” presented at Int. Conf. on Thermal Reactor Safety 

(NUCSAFE 88), Avignon, France, October 1988.

A15. Slama, G., P. Petrequin, and T. Mager, “Effect of Aging on Mechanical Properties of 

Austenitic Stainless Steel Castings and Welds,” presented at SMIRT Post-Conference 

Seminar 6, Assuring Structural Integrity of Steel Reactor Pressure Boundary Components,

Monterey, CA, Aug. 29–30, 1983.

General Electric Global Research, Niskayuna, NY, USA

A16. Morra, M., "Program on Technology Innovation: Scoping Study of Low Temperature Crack 

Propagation for 182 Weld Metal in BWR Environments and for Cast Austenitic Stainless 

Steel in PWR Environments (Revision 1)," EPRI 1020957, Electric Power Research 

Institute, Palo Alto, CA, May 2010.

George Fischer, Switzerland 

A17. Trautwein, A., and W. Gysel, “Influence of Long Time Aging of CF-8 and CF-8M Cast 

Steel at Temperatures between 300 and 500°C on the Impact Toughness and the 

Structure Properties,” in Spectrum, Technische Mitteilungen aus dem+GF+Konzern, 

No. 5, May 1981; also in Stainless Steel Castings, V.G. Behal and A.S. Melilli, eds., 

STP 756, pp. 165–189, 1982.

Japan Nuclear Energy Safety Organization, Japan 

A18. JNES (Japan Nuclear Energy Safety Organization), “Investigation Report on the Integrity 

of Thermally-Embrittled Cast Stainless Steel Pipe,” JNES-SS-0602, Nuclear Energy 

System Safety Division, April 2006. 
D-3

The Kansia Electric Power Co., Inc., Japan 

A19. Tanaka, T., S. Kawaguchi, N. Sakamoto, and K. Koyama, “Thermal Aging of Cast Duplex 

Stainless Steels,” Joint ASME/JSME Pressure Vessel and Piping Conference – Structural 

Integrity of Pressure Vessels, Piping, and Components, Honolulu, HI, July 23–27, pp. 

141–146, 1995. 

Materials Engineering Associates, Inc., 

A20. Hiser, A.L., “Tensile and J-R Curve Characterization of Thermally Aged Cast Stainless 

Steels,” NUREG/CR-5024, MEA-2229, Nuclear Regulatory Commission, Washington DC, 

September 1988. 

Mitsubishi Heavy Industry, Japan 

A21. Suzuki, I., M. Koyama, S. Kawaguchi, H. Mimaki, M. Akiyama, T. Okuba, Y. Mishima, and 

T.R. Mager, "Long Term Thermal Aging of Cast Duplex Stainless Steels," Intl. Conf. on 

Nucl. Eng. (ICONE-4), American Society of Mechanical Engineers, New York, NY, 

pp. 253–257, 1996.

A22. Kawaguchi, S., T. Nagasaki, and K. Koyama, “Prediction Method of Tensile Properties and 

Fracture Toughness of Thermally Aged Cast Duplex Stainless Steel Piping," The 5th Intl. 

Conf. on Nucl. Eng. (ICONE-5), ICONE5-2379, May 26–30, American Society of 

Mechanical Engineers, New York, NY, 1997. 

Ringhals Nuclear Power Plant, Sweden 

A23. Jansson, C., “Degradation of Cast Stainless Steel Elbows after 15 Years in Service,” 

presented at Fontevraud II Intl. Symp., Royal Abbey of Fontevraud, France, September 

10–14, 1990. 

The Welding Institute, UK

A24. Hale, G.E., and S.J. Garwood, “The Effect of Aging on the Fracture Behaviour of Cast 

Stainless Steel and Weldments,” Mater. Sci. Technol. 6, 230–235, 1990.

Westinghouse, 

A25. Landerman, E.I., and W.H. Bamford, “Fracture Toughness and Fatigue Characteristics of 

Centrifugally Cast Type 316 Stainless Steel Pipe after Simulated Thermal Service 

Conditions,” in Ductility and Toughness Considerations in Elevated-Temperature Service,

MPC 8, pp. 99–127, ASME, New York, NY, 1978.

A26. Bamford, W. H., and A.J. Bush, “Fracture Behavior of Stainless Steels,” Elastic-Plastic 

Fracture, STP-668, ASTM, Philadelphia, PA, pp. 553–577, 1979.

General References

A27. Hiser, A.L., F.J. Loss, and B.H. Menke, “J-R Curve Characterization of Irradiated Low 

Upper Shelf Welds,” NUREG/CR-3506, MEA-2028, Materials Engineering Associates Inc., 

April 1984. 
D-4

A28. Saxena, A., and S.J. Hudak, Jr., “Review and Extension of Compliance Information for 

Common crack Growth Specimen,” Int. J. Fracture 5, Vol. 14, 453–468, !978. 

A29. Loss, F.J., B.H. Menke, and R.A. Gray Jr., "Development of J-R Curve Procedures." NRLEPRI Research Program (RP 886-2). Evaluation and Prediction of Neutron Embrittlement in 

Reactor Pressure Vessel Materials Annual Progress Report for FY 1978, J.R. Hawthorn. ed., 

NRL Report 8327, Naval Research Laboratory, August 1979.

A30. Ernst, H.A. “Material Resistance and Instability Beyond J-Controlled Crack Growth,"

Elastic-Plastic Fracture: Second Symp. Vol. I: Inelastic Crack Analysis, ASTM STP 803, 

American Society for Testing and Materials, Philadelphia, PA, 1983.

A31. Hutchinson, J.W., and P.C. Paris, "The Theory of Stability Analysis of J-Controlled Crack 

Growth," in Elastic Plastic Fracture, ASTM STP 668, pp. 37-64, American Society for 

Testing and Materials, Philadelphia, PA, 1983.
E-1

APPENDIX E: PREVIOUS DOCUMENTS OF SERIES

Initial Assessment of the Mechanisms and Significance of Low-Temperature Embrittlement of 

Cast Stainless Steels in LWR Systems, NUREG/CR-5385, ANL-89/17 (August 1990)

Estimation of Fracture Toughness of Cast Stainless Steels during Thermal Aging in LWR 

Systems, NUREG/CR-4513, ANL-90/42 (June 1991)

Estimation of Fracture Toughness of Cast Stainless Steels during Thermal Aging in LWR 

Systems, NUREG/CR-4513, Rev. 1, ANL-93/22 (August 1994) 

Tensile-Property Characterization of Thermally Aged Cast Stainless Steels, NUREG/CR-6142, 

ANL-93/35 (February 1994)

Mechanical Properties of Thermally Aged Cast Stainless Steels from Shippingport Reactor 

Components, NUREG/CR-6275, ANL-94/37 (April 1995)





NUREG/CR-4513

Revision 2

Estimation of Fracture Toughness of Cast Stainless Steels during Thermal 

Aging in LWR Systems