Properties of Anchor Rods Removed

from San Francisco-Oakland Bay Bridge 

PUBLICATION NO. FHWA-HRT-15-057 AUGUST 2015

Research, Development, and Technology

Turner-Fairbank Highway Research Center

6300 Georgetown Pike

McLean, VA 22101-2296
FOREWORD

This report documents independent testing results of failed anchor rod material removed from 

the San Francisco-Oakland Bay Bridge at Pier E2. The work was conducted in a time period 

when the California Department of Transportation was in the midst of an investigation into the 

cause of the anchor rod failures, and the work conducted by the Federal Highway Administration 

was in support of that investigation. Testing included mechanical, chemical, and microstructural 

characterization of two pieces of anchor rod. 

This report would benefit those interested in high-strength steel bolts or rods used for the 

construction of steel bridges, including State transportation departments, researchers, and design 

consultants. 

Jorge E. Pagán-Ortiz

Director, Office of Infrastructure

Research and Development

Notice

This document is disseminated under the sponsorship of the U.S. Department of Transportation 

in the interest of information exchange. The U.S. Government assumes no liability for the use of 

the information contained in this document.

The U.S. Government does not endorse products or manufacturers. Trademarks or 

manufacturers’ names appear in this report only because they are considered essential to the 

objective of the document.

Quality Assurance Statement

The Federal Highway Administration (FHWA) provides high-quality information to serve 

government, industry, and the public in a manner that promotes public understanding. Standards 

and policies are used to ensure and maximize the quality, objectivity, utility, and integrity of its 

information. FHWA periodically reviews quality issues and adjusts its programs and processes to 

ensure continuous quality improvement.
TECHNICAL REPORT DOCUMENTATION PAGE

1. Report No.

FHWA-HRT-15-057

2. Government Accession No. 3. Recipient’s Catalog No.

4. Title and Subtitle

Properties of Anchor Rods Removed from San FranciscoOakland Bay Bridge

5. Report Date

August 2015

6. Performing Organization Code: 

7. Author(s)

Justin M. Ocel, Ph.D., P.E.; and Jason Provines

8. Performing Organization Report No. 

9. Performing Organization Name and Address

Federal Highway Administration

Bridge and Foundation Engineering Team (HRDI-40)

Turner-Fairbank Highway Research Center

6300 Georgetown Pike

McLean, VA 22101-2296

10. Work Unit No.

11. Contract or Grant No.

DTFH61-10-D-00017

12. Sponsoring Agency Name and Address

Office of Infrastructure Research and Development

Federal Highway Administration

6300 Georgetown Pike

McLean, VA 22101-2296

13. Type of Report and Period Covered

Final Report—July 2013 to January 2015

14. Sponsoring Agency Code

HRDI-40

15. Supplementary Notes

This staff study (HRDI-40) was conducted with support from Jason Provines of Professional Service Industries, 

Inc., (PSI) of Herndon, VA, working under the Federal Highway Administration’s Support Services for the 

Structures Laboratories contract. Justin Ocel (FHWA) managed the mechanical testing, and Mr. Provines (PSI) 

conducted the metallography. The Contracting Officer’s Representative was Fassil Beshah, HRDI-40.

16. Abstract

In March 2013, the construction contractor for the new self-anchored suspension bridge between San Francisco

and Oakland, CA, tensioned the threaded rods between the bearings/shear keys and the concrete pier cap. Within 

days of completion, it was discovered that one-third of the rods for the two shear keys on Pier E2 had fractured. 

An investigation began to determine the root cause for the fractures. The work reported herein was in support of 

that investigation at the request of the Federal Highway Administration California Division office. It includes 

data on the mechanical, chemical, and microstructural properties of two samples removed from Pier E2.

The testing showed a variation in material properties between the surface and core of the rods. It was concluded 

that improper heat treatment of the rods caused this variation. In addition, the tensile and hardness properties 

could have been judged to be in nonconformance depending on interpretation of the ASTM standards. It is 

recommended that the ASTM A354 and/or F606 standards be revised to provide more guidance on sampling for 

tensile and hardness properties for large-diameter products as well as guidance on impact toughness. 

17. Key Words

Anchor rod, Chemical analysis, Hardness testing, 

ASTM A354, Tensile testing, Impact testing, 

Fracture toughness 

18. Distribution Statement

No restrictions. This document is available through the 

National Technical Information Service;

Springfield, VA 22161.

http://www.ntis.gov/about/contact.aspx

19. Security Classif. (of this report)

Unclassified

20. Security Classif. (of this page)

Unclassified

21. No. of Pages

64

22. Price

N/A

Form DOT F 1700.7 (8-72) Reproduction of completed page authorized
ii

SI* (MODERN METRIC) CONVERSION FACTORS 

APPROXIMATE CONVERSIONS TO SI UNITS

Symbol When You Know Multiply By To Find Symbol 

LENGTH

in inches 25.4 millimeters mm 

ft feet 0.305 meters m 

yd yards 0.914 meters m 

mi miles 1.61 kilometers km 

AREA 

in2 square inches 645.2 square millimeters mm2

ft2 square feet 0.093 square meters m2

yd2 square yard 0.836 square meters m2

ac acres 0.405 hectares ha

mi2 square miles 2.59 square kilometers km2

VOLUME 

fl oz fluid ounces 29.57 milliliters mL 

gal gallons 3.785 liters L 

ft3 cubic feet 0.028 cubic meters m3 

yd3 cubic yards 0.765 cubic meters m3 

NOTE: volumes greater than 1000 L shall be shown in m3

MASS oz ounces 28.35 grams g

lb pounds 0.454 kilograms kg

T short tons (2000 lb) 0.907 megagrams (or "metric ton") Mg (or "t") 

TEMPERATURE (exact degrees) o

F Fahrenheit 5 (F-32)/9 Celsius o

C 

or (F-32)/1.8 

ILLUMINATION 

fc foot-candles 10.76 lux lx

fl foot-Lamberts 3.426 candela/m2 cd/m2

FORCE and PRESSURE or STRESS 

lbf poundforce 4.45 newtons N 

lbf/in2 poundforce per square inch 6.89 kilopascals kPa 

APPROXIMATE CONVERSIONS FROM SI UNITS 

Symbol When You Know Multiply By To Find Symbol 

LENGTH mm millimeters 0.039 inches in 

m meters 3.28 feet ft 

m meters 1.09 yards yd 

km kilometers 0.621 miles mi 

AREA mm2 square millimeters 0.0016 square inches in2 

m2 square meters 10.764 square feet ft2 

m2 square meters 1.195 square yards yd2 

ha hectares 2.47 acres ac

km2 square kilometers 0.386 square miles mi2 

VOLUME 

mL milliliters 0.034 fluid ounces fl oz 

L liters 0.264 gallons gal 

m3 cubic meters 35.314 cubic feet ft3 

m3 cubic meters 1.307 cubic yards yd3 

MASS 

g grams 0.035 ounces oz

kg kilograms 2.202 pounds lb

Mg (or "t") megagrams (or "metric ton") 1.103 short tons (2000 lb) T 

TEMPERATURE (exact degrees) o

C Celsius 1.8C+32 Fahrenheit o

F 

ILLUMINATION 

lx lux 0.0929 foot-candles fc 

cd/m2 candela/m2 0.2919 foot-Lamberts fl

FORCE and PRESSURE or STRESS 

N newtons 0.225 poundforce lbf 

kPa kilopascals 0.145 poundforce per square inch lbf/in2

*SI is the symbol for the International System of Units. Appropriate rounding should be made to comply with Section 4 of ASTM E380. 

(Revised March 2003)
iii

TABLE OF CONTENTS

CHAPTER 1. INTRODUCTION................................................................................................ 1

SCOPE OF WORK .................................................................................................................. 2

CHAPTER 2. TESTING PLAN .................................................................................................. 7

CHAPTER 3. EXPERIMENTAL RESULTS.......................................................................... 11

TENSILE TESTING .............................................................................................................. 11

HARDNESS TESTING.......................................................................................................... 14

CHARPY IMPACT TESTING ............................................................................................. 20

CHEMICAL ANALYSIS....................................................................................................... 23

THREAD ROOT CRACKING ............................................................................................. 24

METALLOGRAPHIC EVALUATION............................................................................... 24

Polished Sample Analysis...................................................................................................... 25

Etched Sample Analysis........................................................................................................ 28

CHAPTER 4. CONCLUSIONS................................................................................................. 37

CHAPTER 5. RECOMMENDATIONS ................................................................................... 39

APPENDIX A. TABLES OF HARDNESS TESTING RESULTS......................................... 41

APPENDIX B. TABLES OF CHARPY TESTING RESULTS.............................................. 53

REFERENCES............................................................................................................................ 55
iv

LIST OF FIGURES

Figure 1. Schematic. Plan view of S2 shear key hole pattern..........................................................3

Figure 2. Schematic. Section Z-Z cross-sectional view of S2 shear key.........................................4

Figure 3. Photo. Received threaded sample after cleaning..............................................................4

Figure 4. Photo. Received unthreaded sample after cleaning..........................................................5

Figure 5. Schematic. Cutting plan for unthreaded sample...............................................................8

Figure 6. Schematic. Cutting plan for threaded sample...................................................................9

Figure 7. Schematic. Geometry of round bar tensile coupon ........................................................10

Figure 8. Graph. Engineering stress versus strain curves for all tensile specimens ......................12

Figure 9. Graph. Variation of yield and tensile properties through the rod radius........................13

Figure 10. Graph. Variation in area reduction and elongation through the rod radius..................13

Figure 11. Schematic. Location of hardness readings in unthreaded sample ................................15

Figure 12. Schematic. Location of hardness readings in threaded sample ....................................16

Figure 13. Graph. Bubble contour plot of hardness readings on unthreaded sample ....................17

Figure 14. Graph. Bubble contour plot of hardness readings on threaded sample ........................18

Figure 15. Graph. Constant radius average hardness of unthreaded sample .................................19

Figure 16. Graph. Constant radius average hardness of threaded sample .....................................19

Figure 17. Graph. Charpy energy results from unthreaded sample ...............................................21

Figure 18. Graph. Charpy percent-shear results from unthreaded sample ....................................21

Figure 19. Graph. Charpy energy results from threaded sample ...................................................22

Figure 20. Graph. Charpy percent-shear results from threaded sample. .......................................22

Figure 21. Photo. Unetched example of stringer inclusions near center of rod at 200×

magnification ...........................................................................................................................25

Figure 22. Photo. Unetched example of stringer inclusions near center of rod at 500×

magnification ...........................................................................................................................26

Figure 23. Photo. Electron beam image of inclusion 1 from SEM and associated images at 

same location taken with an EDX detector..............................................................................27

Figure 24. Photo. Electron beam image of inclusion 2 from SEM and associated images at 

same location taken with an EDX detector..............................................................................28

Figure 25. Photo. Mounted cross section of threaded rod etched with Marshall’s reagent...........29

Figure 26. Photo. Micrograph near thread root etched with Marshall’s reagent at 50×

magnification ...........................................................................................................................30

Figure 27. Photo. Micrograph near rod center etched with Marshall’s reagent at 50×

magnification ...........................................................................................................................30

Figure 28. Photo. Micrograph near thread root etched with Marshall’s reagent at 500×

magnification ...........................................................................................................................31

Figure 29. Photo. Micrograph near rod center etched with Marshall’s reagent 500×

magnification ...........................................................................................................................32

Figure 30. Photo. Micrograph near thread root etched with 10-percent potassium 

metabisulfite at 500× magnification ........................................................................................33

Figure 31. Photo. Micrograph near rod core etched with 10-percent potassium 

metabisulfite at 500× magnification ........................................................................................33

Figure 32. Photo. Macrograph of thread with micrograph overlays taken at thread root and 

crest, etched with 2-percent nital .............................................................................................34
v

Figure 33. Photo. Micrograph of typical delamination at thread surface etched with 

2-percent nital at 500× magnification ......................................................................................35
vi

LIST OF TABLES

Table 1. Results of tensile tests......................................................................................................11

Table 2. Chemical composition (percent by weight).....................................................................24

Table 3. Rockwell C hardness results for unthreaded sample. ......................................................41

Table 4. Rockwell C hardness results for threaded sample. ..........................................................47

Table 5. Raw data unthreaded sample Charpy specimens.............................................................53

Table 6. Raw data for threaded sample Charpy specimens. ..........................................................54
vii

LIST OF ABBREVIATIONS

AASHTO America Association of State Highway and Transportation Officials

AISI American Iron and Steel Institute

Caltrans California Department of Transportation

CVN Charpy V-Notch

EDM Electric Discharge Machining

EDX Energy-Dispersive X-Ray

FHWA Federal Highway Administration

HRC Rockwell C Hardness

LAST Lowest Anticipated Service Temperature

SAS Self-Anchored Suspension

SEM Scanning Electron Microscope

SSRC Structural Stability Research Council

TFHRC Turner-Fairbank Highway Research Center

1

CHAPTER 1. INTRODUCTION

On Labor Day, September 2, 2013, the California Department of Transportation (Caltrans)

opened the new San Francisco-Oakland Bay Bridge between Yerba Buena Island and Oakland, 

CA. The signature span of the bridge is a steel orthotropic box girder in a self-anchored 

suspension (SAS) configuration. This new bridge is a more robust replacement for the doubledeck steel truss bridge that had experienced a localized collapse of a deck portion during the 

1989 Loma Prieta earthquake.

Overall construction of the new bridge began in January 2002, but SAS construction did not 

begin until 2007. One of the key design elements of the SAS was the connection of the 

superstructure to Pier E2 through large bearings and shear keys. The four shear keys were meant 

to resist lateral seismic forces and prevent excessive lateral movement of the four main bearings.

Because of the massiveness of the bridge, the seismic forces would be quite large, thus requiring 

large connecting elements to clamp the bearings and shear keys to the pier cap. In this case, 

large-diameter, high-strength rods were used as the connecting element so large clamping forces 

could be developed. It was desired to specify a rod material with a 150-ksi minimum tensile 

strength, which is equivalent to a normal ASTM A490 high-strength structural bolt.(1) However, 

the required clamping forces necessitated the use of 3-inch-diameter rods, which is outside of the 

scope of ASTM A490. Thus, the material was specified as an ASTM A354 BD grade 

material.(1,2) This also came with a slight reduction on strength, because at this diameter, ASTM 

A354 BD sets a 140-ksi minimum tensile strength.(2) In addition, because the bridge is in a 

marine environment, the rods were specified to be galvanized for added corrosion resistance.

The other unique aspect of the shear key design is that two of the shear keys were directly over a

column supporting the pier cap. Unlike the bearings and the two interior shear keys that could be 

bolted to the pier cap with rods running all the way through the pier cap, those for the shear keys 

over the columns had to be dead-ended within the pier cap. This meant the rods had to be 

installed within the pier cap before it was cast, long before they would be tensioned. The shear 

key rods were fabricated in 2008 and were the first of many batches of galvanized ASTM A354 

BD rods fabricated for various portions of the SAS. References to the ASTM A354 standard

throughout this report are purposely made to the 2007 edition because these specifications were

enforced in the fabrication of the Pier E2 shear key anchor rods.

In March 2013, the contractor erecting the bridge began to tension the 96 rods for the 2 shear 

keys on Pier E2 over the pier columns. Within days, they discovered that 32 of the rods had 

fractured. With the bridge fully erected, these rods were impossible to replace because they were 

dead-ended in the pier cap. At the time this report was written, the investigation was still 

ongoing, but a variety of factors are believed to have contributed to the fractures, such as 

improper heat treatment, poor raw material, and most likely hydrogen embrittlement. To date, all 

fractures have been isolated to the 2008 batch of rods (96 in total). More detailed information on 

the bridge design and preliminary investigation into the failure mechanism(s) of the rods can be 

found in the Toll Bridge Program Oversight Committee’s Report on the A354 Grade BD HighStrength Steel Rods on the New East Span of the San Francisco-Oakland Bay Bridge With 

Findings and Decisions.

(3)
2

SCOPE OF WORK

In June 2014, the Federal Highway Administration (FHWA) California Division Office 

requested that Turner-Fairbank Highway Research Center (TFHRC) perform material testing and 

analytical work on two rod samples obtained from the 2008 batch of rods. The purpose of the 

testing was to supply Caltrans with unbiased, independent results.

Two samples were shipped to TFHRC. One was approximately 3 inches long and was from a 

threaded portion of the E8 rod of the S2 shear key. Figure 1 shows the alphanumeric grid system 

used to identify the 48 anchor rods holding the S2 shear key to Pier E2; the circle with the black 

fill represents the E8 location. Figure 2 shows an elevation view of the S2 shear key showing that 

the 3-inch-long sample was taken from approximately the middle portion of the threaded region

on the top side of the rod. The second sample was approximately 13.5 inches long and was from 

an unthreaded portion of a rod from an unknown location. It was verbally communicated that this 

larger sample was from the 2008 batch of rods. Pictures of the two rod samples are shown in

figure 3 and figure 4.

TFHRC was asked to test impact toughness, hardness, strength, and elongation, in addition to 

conducting microscopic inspection of thread roots for cracks. TFHRC was free to suggest 

additional tests if there was remaining material.
3

Figure 1. Schematic. Plan view of S2 shear key hole pattern.

A B C D E F G H

1

2

3

4

5

6

7

8

N

Z

Threaded

Sample

Location
4

Figure 2. Schematic. Section Z-Z cross-sectional view of S2 shear key.

Figure 3. Photo. Received threaded sample after cleaning.
5

Figure 4. Photo. Received unthreaded sample after cleaning.

7

CHAPTER 2. TESTING PLAN

The unthreaded sample offered the greatest opportunity because of the volume of material 

provided. TFHRC staff removed three separate portions of this piece, as shown in the cutting 

plan of figure 5. A 0.38-inch-thick portion was removed for hardness testing. A 3.75-inch-long 

portion was used to make tensile testing coupons and Charpy specimens as shown in section A-A

of the figure, where the circles represent the tensile specimens, and the squares represent Charpy 

specimens (with the hatched region in the square representing the location of the Charpy notch).

A 2.25-inch-long piece was used exclusively for Charpy specimens as shown in section B-B of 

the figure. The Charpy and tensile specimens were rough cut out with a wire electric discharge 

machining (EDM) machine to maximize the number of specimens that could come from each 

portion. 

The threaded sample was too short to perform any tensile testing, and this piece was devoted to 

assessing Charpy impact toughness, hardness, visual inspection of macro sections, and 

microstructural characterization. It was cut according to the schematic shown in figure 6. A 

0.38-inch-thick portion was removed for hardness testing. Three longitudinal cross sections were 

removed, represented by the hatched area in section C-C of figure 6. These would be used for 

microstructural characterization and examination of the thread roots. The remainder of the 

section was turned into Charpy specimens, also shown in section C-C.

The tensile specimens were ASTM E8 round bar specimens with 0.25-inch reduced diameters 

and 1-inch gauge lengths as shown in figure 7.

(4) The idea behind using a small specimen was to 

explore the variation in strength through the rod. As can be seen in the sampling plan, tensile 

specimens were taken at four different distances away from center of the rod cross section. This 

process allowed for assessment of the uniformity of tensile properties through the cross section.

The Charpy specimens followed a similar approach in that sampling was performed at different 

distances from the center of the rod cross section. Many Charpy specimens were needed to 

develop full transition curves by testing specimens at multiple temperatures.
8

Note: All units shown in the figure are in inches.

Figure 5. Schematic. Cutting plan for unthreaded sample.
9

Note: All units shown in the figure are in inches.

Figure 6. Schematic. Cutting plan for threaded sample.
10

Note: All units shown in the figure are in inches.

Figure 7. Schematic. Geometry of round bar tensile coupon.
11

CHAPTER 3. EXPERIMENTAL RESULTS

TENSILE TESTING

The testing was performed in a digitally controlled servovalve hydraulic test frame with 

hydraulic grips. The specimens were loaded initially at a slow rate of approximately 36 ksi/min, 

whereas the standard allows for a range between 10 and 100 ksi/min. Once yielding had 

occurred, the loading rate was incrementally increased until it achieved approximately 

0.07 strain/min, where the standard allows for a range of 0.05 to 0.50 strain/min. Strain was 

measured with a clip-on extensometer.

The pertinent results are reported in table 1, and plots of the stress versus strain results are shown 

in figure 8. In three locations, duplicate specimens from the same radial location were extracted 

and tested, although only one specimen could be made from the core of the rod. In figure 8, 

duplicates are plotted using the same line type, and the fracture point of each specimen is labeled 

with the specimen name from table 1. With each plot, note the three pauses shortly after the yield 

was exceeded. This is an artifact of the testing procedure used by TFHRC, and this is related to a 

Structural Stability Research Council (SSRC) recommendation in the Guide to Stability Design 

Criteria for Metal Structures.

(5) SSRC recommends three pauses in loading after yielding to 

observe the load drop as the material relaxes under zero strain rate (i.e., static conditions). Holds 

were maintained for 90 s. The static yield is reported as the intersection of the best-fit line 

through the three static holds intersecting the 0.02-percent offset line, and it is reported for 

informational purposes only.

Table 1. Results of tensile tests.

Specimena

Modulus

(ksi)

0.2-Percent

Offset 

Yield 

Stressb

(ksi)

Static 

Yield 

Stress

(ksi)

Tensile 

Strengthc

(ksi)

Extensometer 

Percent 

Elongation

Percent 

Reduction 

in Area

Distance 

From 

Core of 

Rod

(inches)

T1 29,670 159.7 149.9 174.3 14.8 50.1 1.225

T7 30,165 157.0 158.6 172.0 14.7 49.5 1.225

T2 29,640 145.1 153.7 168.6 11.0d 41.0 1.023

T6 29,826 151.8 158.5 174.9 11.4d 35.9e 1.023

T3 30,014 127.0 137.2 156.6 12.7d 33.8e 0.613

T4 29,642 127.0 136.9 157.7 16.1 37.9e 0.613

T5 30,506 119.8 132.2 151.4 12.7d 33.5e 0.000 a

Specimen names correlate to the locations shown in section A-A of figure 5. b

ASTM A354 grade BD requires a minimum of 115 ksi.

(2)

c

ASTM A354 grade BD requires a minimum of 140 ksi.

(2)

d

Failed to meet minimum 14-percent elongation in a 2-inch gauge length in accordance with ASTM A354 grade BD.

(2)

e

Failed to meet minimum reduction in area of 40 percent in accordance with ASTM A354 grade BD.

(2)
12

Figure 8. Graph. Engineering stress versus strain curves for all tensile specimens.

All the specimens met the yield and tensile strength requirements of ASTM A354 grade BD.(2)

However, four specimens could not achieve the elongation requirement, and four (not all the 

same) could not achieve the reduction in area requirement. ASTM A354 requires a minimum 

reduction of area of 40 percent and minimum elongation of 14 percent on a 2-inch gauge length. 

The TFHRC specimens used a 1-inch gauge length but maintained the 4:1 aspect ratio assumed 

by ASTM E8; therefore, the measured elongation value is comparable to the standard value.(4)

The property variation through the radius of the rod is shown in figure 9 and figure 10; in 

particular, yield strength, tensile strength, and area reduction all showed a trend toward 

decreasing values moving toward the core of the rod. 
13

Figure 9. Graph. Variation of yield and tensile properties through the rod radius.

Figure 10. Graph. Variation in area reduction and elongation through the rod radius.
14

HARDNESS TESTING

Hardness testing was performed on 0.38-inch-thick cross sections removed from each of the 

threaded and unthreaded samples. Hardness testing was performed with a diamond indenter and 

the Rockwell C scale. Figure 11 shows the locations of the 237 hardness readings taken on the 

unthreaded rod. Generally, the locations were laid out in a polar coordinate system, with 

measurements taken every one-eighth of an inch radially away from the core and every 

15 degrees clockwise around the circle. According to the ASTM E18 standard, hardness readings 

must be spaced more than 3 indent diameters away from other indents, or 2.5 diameters from an 

edge.(6) This restricted measurement spacing in the core region to every 30 or 45 degrees at the

same radial distance. The same philosophy was used for the threaded sample, although the 

“edge” was considered to be the thread root, which led to only 205 total measurements.

Figure 12 shows the locations of the measurements of the threaded rod. All the individual 

hardness measurements for both rods are reported in appendix A.
15

Note: All units shown in the figure are in inches.

spa. = Spaces.

Figure 11. Schematic. Location of hardness readings in unthreaded sample.
16

Note: All units shown in the figure are in inches.

spa. = Spaces.

Figure 12. Schematic. Location of hardness readings in threaded sample.

All hardness data for each of the rods were condensed into one bubble contour plot for each of 

the samples, as shown in figure 13 and figure 14. In these plots, a bubble is plotted in a Cartesian 

system matching the measurement locations shown in figure 11 and figure 12, and the diameter 

and color fill of each bubble is scaled to the hardness reading. Such plots can help visualize any 

spacial anomalies associated with the hardness readings. Both rods show the same linear 

decreasing trend in the hardness traversing from the surface of the rod to the core. The 

unthreaded sample showed more anomalous readings, with low readings intermixed near the 

surface and high readings near the core. This may be due to normal scatter in hardness readings 

or an indication of a rod with more inclusions within it. The threaded sample did not have the 
17

same anomalous readings, although it demonstrated a trend of slightly higher hardness at the 

surface in the upper left quadrant of the plot than the rest of the perimeter. These readings may 

suggest nonuniform heat treatment of this particular rod. 

Figure 13. Graph. Bubble contour plot of hardness readings on unthreaded sample.

-1.5

-1

-0.5

0

0.5

1

1.5

-1.5 -1 -0.5 0 0.5 1 1.5 2 2.5

Y-Coordinate (in.)

X-Coordinate (in.)

39< HRC <40

38< HRC <39

37< HRC <38

36< HRC <37

35< HRC <36

34< HRC <35

33< HRC <34

32< HRC <33

31< HRC <32

30< HRC <31

HRC <30
18

Figure 14. Graph. Bubble contour plot of hardness readings on threaded sample.

To better illustrate the variation of hardness through each rod, the two graphs in figure 15 and 

figure 16 were constructed by averaging all the hardness readings at a common radial distance. 

Each plot shows the outer surface of the rod as a vertical line. Red and blue dashed lines indicate 

the maximum and minimum hardness specified for ASTM A354 grade BD material, and in the 

case of the threaded rod, the thread root is shown as a vertical gray line. The actual data shown 

with green points and a green line represent the average of all the readings taken at a common 

radius. The reading taken at the exact core was neglected because it was only a single point 

measurement. Error bars are shown for each of the data points, and they represent the 

one standard deviation spread from all the measurements at each common radius. Each has a 

core hardness (Rockwell C Hardness (HRC)) in the low 30s, with an increasing trend to about 

1 inch away from the core. From this point out to the surface, each rod appears to be uniformly 

hardened with average hardness ranging from about 37 to 38 HRC. In the sense of average 

hardness (solid green line), neither rod exceeded the maximum hardness of 39 HRC specified in 

ASTM A354; however, near the core region, each did go below the minimum ASTM A354 

hardness of 31 HRC. The location for hardness testing to ensure conformance to the ASTM 

A354 standard is defined by the ASTM F606 standard.(7) However, the hardness measurement 

locations outlined in ASTM F606 are ambiguous for this particular product diameter. In the case 

of arbitration, four equidistant measurements are taken at the mid-radius. If the arbitration 

locations were used, each of the two rod samples tested met the hardness standard of ASTM 

A354 grade BD material; however, many individual readings near the core were lower than the 

minimum specified hardness, and some individual readings near the surface were in excess of the 

maximum specified hardness.

-1.5

-1

-0.5

0

0.5

1

1.5

-1.5 -1 -0.5 0 0.5 1 1.5 2 2.5

Y-Coordinate (in.)

X-Coordinate (in.)

39< HRC <40

38< HRC <39

37< HRC <38

36< HRC <37

35< HRC <36

34< HRC <35

33< HRC <34

32< HRC <33

31< HRC <32

30< HRC <31

HRC <30
19

Figure 15. Graph. Constant radius average hardness of unthreaded sample.

Figure 16. Graph. Constant radius average hardness of threaded sample.

0

5

10

15

20

25

30

35

40

45

0 0.25 0.5 0.75 1 1.25 1.5 1.75

Average HRC

Distance From Rod Core (in.)

Maximum HRC for ASTM A354 Grade BD = 39

Minimum HRC for ASTM A354 Grade BD = 31

Surface of Rod
20

CHARPY IMPACT TESTING

Specimens were roughed out of the rods using an EDM machine and then finished to its final 

dimensions by surface grinding to remove the heat affected zone caused by the EDM machine. A 

notch was cut into the specimens according to the “type A” geometry from the ASTM E23 

standard.

(8) When numerous specimens were available from the same radial location within the 

sample, they were tested at a variety of temperatures to develop a full temperature–toughness 

transition curve. Testing was performed at temperatures ranging from approximately -60 to 

200 °F to find the upper and lower shelves. When specimens were not replicated, testing was 

performed at approximately 70 °F. A constant temperature bath was used to maintain the

temperature of the specimens until they could be tested. For cold temperatures, the bath used 

denatured ethanol, and for temperatures above 70 °F, ethyl glycol was used.

The raw data for all the Charpy specimens can be found in appendix B. The data are plotted in 

figure 17 through figure 20, respectively, for the unthreaded and threaded samples and for both 

the fracture energy and the percent-shear fracture. When multiple samples were taken from an 

equidistant location away from the rod surface and tested at a variety of temperatures, a 

regression was performed on all that particular data. The regression was a least-square fit to a 

four-parameter hyperbolic tangent function. This four-parameter function looks like a step 

function with a gradual transition where the four parameters define the lower shelf energy, upper 

shelf energy, transition temperature, and transition temperature range. The regression represents 

the average through all the data, and it was plotted with a solid line of the same color as the 

individual data points. A couple observations can be made regarding the four figures compared 

with normal structural steels. First, the material exhibits a toughness transition over a wide 

temperature range (about 120 to 140 °F). Second, there is not a large disparity in the lower and 

upper shelf energies. Third, the material closer to the core of the rods shows a similar shaped

transition curve to that from the surface, although it is shifted downward on the energy axis.

Fourth, despite coming close to the upper shelf in terms of fracture energy, the majority of the 

specimens attained less than 40-percent shear on the fracture surface; more ductile steel would 

exhibit closer to 100-percent shear on the upper shelf.
21

Figure 17. Graph. Charpy energy results from unthreaded sample.

Figure 18. Graph. Charpy percent-shear results from unthreaded sample.

0

5

10

15

20

25

30

35

40

-80 -60 -40 -20 0 20 40 60 80 100 120 140 160 180 200 220

Fracture Energy (ft-lb)

Temperature (°F)

Notch 0.14 in. from rod surface

Notch 0.38 in. from rod surface

Notch 0.60 in. from rod surface

Notch 0.84 in. from rod surface

Notch at core of rod

Regressed curve fit for 

specimens with notches 

0.14 in. from rod surface

Regressed curve fit for 

specimens with notches 

0.84 in. from rod surface

0

10

20

30

40

50

60

70

80

90

100

-80 -60 -40 -20 0 20 40 60 80 100 120 140 160 180 200 220

Percent Shear

Temperature (°F)

Notch 0.14 in. from rod surface

Notch 0.38 in. from rod surface

Notch 0.60 in. from rod surface

Notch 0.84 in. from rod surface

Notch at core of rod

Regressed curve fit for 

specimens with notches 

0.14 in. from rod surface

Regressed curve fit for 

specimens with notches 

0.84 in. from rod surface
22

Figure 19. Graph. Charpy energy results from threaded sample.

Figure 20. Graph. Charpy percent-shear results from threaded sample.

ASTM A354 has no established metrics of notch toughness. For reference, the American 

Association of State Highway and Transportation Officials (AASHTO) has established notch 

toughness requirements to mitigate fracture in welded steel bridges fabricated from hot-rolled 

steel.(9) The AASHTO toughness requirements ensure materials are not on the lower shelf of 

toughness at the possible lowest anticipated service temperature (LAST).(10) The popular 

0

5

10

15

20

25

30

35

40

-80 -60 -40 -20 0 20 40 60 80 100 120 140 160 180 200 220

Fracture Energy (ft-lb)

Temperature (°F)

Notch 0.33 in. from rod surface

Notch at core of rod

Regressed curve fit for 

specimens with notches 

0.33 in. from rod surface

Regressed curve fit for 

specimens with notches 

at core

0

10

20

30

40

50

60

70

80

90

100

-80 -60 -40 -20 0 20 40 60 80 100 120 140 160 180 200 220

Percent Shear

Temperature (°F)

Notch 0.33 in. from rod surface

Notch at core of rod

Regressed curve fit for 

specimens with notches 

0.33 in. from rod surface

Regressed curve fit for 

specimens with notches at core
23

minimum toughness of 15 ft-lb1 was used by AASHTO, although it is higher for some grades 

and for members without redundancy.(11) The toughness requirements were also paired with a 

test temperature that relied on a temperature shift concept to equate the low dynamic toughness 

from a Charpy V-notch (CVN) test to that of a static plain strain fracture test because most 

bridges operate at near static conditions. Once the material yield strength exceeds 140 ksi, there 

is no temperature shift, and this must be considered when choosing a test temperature for a highstrength anchor rods. The LAST for San Francisco would be about 22 °F,2 and based on the 

strength of the rods, there would be little to no temperature shift in the toughness requirements, 

so the LAST defines the CVN temperature. 

This report does not purport to establish a CVN requirement for anchor rods. As the prior 

discussion points outs, existing bridge CVN requirements have been established for welded, hotrolled product, and a threaded fastener is different because it does not have the same residual 

stress or notch acuity as a welded object would have. However, if 15 ft-lb at 22 °F is used, the 

data collected for the threaded and unthreaded samples do not pass this criterion. The threaded 

sample demonstrated less than 15 ft-lb of energy throughout the rod at 22 °F, and the unthreaded 

sample would pass at the surface, but not at its core.

CHEMICAL ANALYSIS

Three spent Charpy specimen halves and extra material from machining of a fourth Charpy 

specimen were sent to an independent metallurgical laboratory for a standard nine-element 

compositional analysis. Two specimens were selected from both the threaded sample (F1 and F4) 

and the unthreaded sample (A1 and D0). For each rod, the two samples were taken from near the 

surface and near the core to see whether there was any evidence of segregation. The results of the 

chemical analysis are shown in table 2. According to quality control documentation, the rods 

were made from a grade 4140 alloy furnished under the ASTM A322 specification.(12) Three of 

the four samples were in conformance of ASTM A322 chemical requirements. The exception 

was the sample from location A1, which slightly exceeded the range for carbon and chromium.

The results show all four specimens meet the ASTM A354 chemical requirements for a product 

analysis.(2) Generally, the four samples had very similar composition, and the chemical analysis 

did not suggest evidence of segregation within the rods, except for the higher carbon and 

chromium content in the A1 sample taken near the surface of the unthreaded rod.

 

1

The 15 ft-lb requirement dates back to analysis of the Liberty ship fractures where most fractures were 

prevented if plates had 10 ft-lb of toughness, and 15 ft-lb was established as a higher performance standard. 2

Determined using a type I extreme value probability distribution input with annual extreme minimum 

temperatures recorded at the San Francisco International Airport from 1948 to 2014. The 22 °F value is based on a 

return period of 300 years, or 0.33 percent chance of exceedance. 
24

Table 2. Chemical composition (percent by weight).

Element

ASTM A322

Requirements

ASTM A354 

Requirements

Location

A1a

Location

D0a

Location

F1b

Location

F4b

Carbon 0.38–0.43 0.33–0.55 0.48c 0.40 0.41 0.38

Manganese 0.75–1.00 — 0.96 0.92 0.99 0.99

Phosphorus 0.035 max 0.040 max 0.015 0.012 0.013 0.012

Sulfur 0.040 max 0.045 max 0.034 0.032 0.036 0.036

Silicon 0.15–0.35 — 0.31 0.27 0.31 0.30

Nickel — — 0.11 0.10 0.11 0.10

Chromium 0.80–1.10 — 1.12c 1.00 1.00 1.04

Molybdenum 0.15–0.25 — 0.15 0.14 0.15 0.15

Copper — — 0.22 0.20 0.21 0.20

— Not specified. 

Max = Maximum.

a

Specimen names correlate to the locations shown in section A-A and section B-B in figure 5. b

Specimen names correlate to the locations shown in section C-C in figure 6. c

Outside the range of ASTM A322.

THREAD ROOT CRACKING

Figure 6 showed three hatched areas that were removed from the threaded portion as longitudinal 

cross sections. The two smaller ones were removed to perform thread root examination, and the 

larger one was removed for the metallographic examination described in the next section. One of 

the smaller sections was damaged by the EDM machine when the specimen dropped during 

cutting and could not be used for evaluation. The second smaller one was sprayed with red dye 

penetrant and allowed to dwell for 1 h before being exposed with a white developer. The goal 

was to highlight any possible indications at the thread root, and after the developer had dried, the 

roots were examined under a stereo zoom microscope. No indications were found on the one 

cross section with red dye.

Ideally, the entire threaded portion should have been examined by wet magnetic particle

inspection before the mechanical test specimens were extracted from it. For timing reasons, that 

did not occur. However, the intact remnants of the threaded portions (i.e., parts left over once the 

Charpy specimens were removed) were eventually inspected using wet fluorescent magnetic 

particle inspection using a black light. Again, no crack indications could be found with the wet 

magnetic particles.

METALLOGRAPHIC EVALUATION

The large longitudinal section removed from the threaded rod, referenced in figure 6, was cut 

into two equal, full-width sections using an abrasive cut-off wheel. Both samples were then 

prepared for metallographic evaluation in accordance with ASTM E3.

(13) The samples were 

thoroughly cleaned and then mounted in a castable epoxy. Once the epoxy had cured, the 

exposed surface of each sample was prepared using a sequence of grinding and polishing. 

Grinding was conducted on a belt grinder using a series of increasingly finer silicon carbide 

grinding papers: 120, 240, 400, and 600 grit. The samples were then polished on a rotating wheel 

polisher using a 1-micron diamond compound on a red felt cloth. Between each grinding and 
25

polishing step, samples were washed with water, cleaned with ethanol, and dried with a warm air 

blower.

Polished Sample Analysis

At this stage, the samples were examined in the as-polished condition under a compact inverted 

metallurgical microscope. Figure 21 and figure 22 show micrographs taken at the rod core at 

magnifications of 200× and 500×, respectively. By examining the samples in the as-polished or 

unetched condition, the large amount of non-metallic stringer inclusions became apparent. 

Although these two micrographs were taken at the rod core, they represent the typical size and 

prevalence of stringers located throughout the entire cross section of the rod. All of the stringers 

were oriented such that they were elongated in the rolling direction of the threaded rod.

Figure 21. Photo. Unetched example of stringer inclusions near center of rod at

200× magnification.
26

Figure 22. Photo. Unetched example of stringer inclusions near center of rod at

500× magnification.

The polished samples were then placed in a scanning electron microscope (SEM) for further 

analysis of inclusions with the energy dispersive X-ray (EDX) detector. Figure 23 and figure 24

show the results of two randomly selected inclusions from within the rod. The electron beam 

image is similar to that obtained from the inverted microscope. However, the EDX detector has 

the ability to transform that image into a domain of elemental composition. For the first 

inclusion, based on the element signatures, this particular inclusion has small nodules of 

manganese sulfide within a matrix of calcium silicate, or slag. The second inclusion appears to 

be simply manganese sulfide. Other inclusions were examined throughout the rod, and all were 

determined to be either manganese sulfides or slag. 
27

Figure 23. Photo. Electron beam image of inclusion 1 from SEM and associated images at 

same location taken with an EDX detector.
28

Figure 24. Photo. Electron beam image of inclusion 2 from SEM and associated images at 

same location taken with an EDX detector.

Etched Sample Analysis

Once the unetched samples were examined, the samples were then freshly polished, and each 

sample was uniquely etched according to ASTM E407.(14) The two etchants selected were 

Marshall’s reagent (ASTM E407, Etchant #223) and 10-percent potassium metabisulfite 

(ASTM E407, Etchant #78).(14) Marshall’s reagent was chosen over the more common 2-percent 

nital etchant (ASTM E407, Etchant #74) because it attacks the ferrite grain boundaries more 

effectively than nital, thus providing more sharpness and completeness to the grain structure 

image. Potassium metabisulfite was selected because it aids in distinguishing between tempered 

and as-quenched martensite as well as other phases.(15)

Figure 25 shows a macrograph of the mounted sample etched with Marshall’s reagent and 

viewed under a stereo zoom microscope. A simple macroscopic examination reveals light and 

dark areas. The dark regions near the threads are the changed microstructure from the quench 

and tempering of the rod. However, there is also non-homogeneity with severe banding present 

in approximately the middle 1.75 inches of the rod, alternating between light and dark etched 

microstructures. The bands are biased to the left side of the rod, with the hardened region deeper 

in the rod on the right side versus the left side. That is, the constant hardened region on the right 

starts at about +0.75 inches all the way to right edge, whereas on the left, the hardened region is 

constant from –1.0 inches to the left edge. This is indicative of some imbalance in the hardening 

operation and correlates to the unbalanced hardness observed in figure 14.
29

Figure 25. Photo. Mounted cross section of threaded rod etched with Marshall’s reagent.

Figure 26 shows a micrograph taken of the sample in figure 25 but at higher magnification under 

a bright field illumination near the thread root. The color is uniform, indicating a consistent 

microstructure. Figure 27 is another micrograph at the same magnification but taken near the 

core of the rod. This figure clearly shows the alternating banded layers of two different 

microstructures.
30

Figure 26. Photo. Micrograph near thread root etched with Marshall’s reagent at

50× magnification.

Figure 27. Photo. Micrograph near rod center etched with Marshall’s reagent at

50× magnification.
31

Figure 28 presents the same micrograph as shown in figure 26 near the thread root but taken at a 

magnification of 500×. This microstructure is mostly tempered martensite and possibly some 

bainite, which is fairly representative of the quenched and tempered 4140 steel that was used for 

the anchor rods. By comparison, figure 29 shows the same micrograph as figure 27 near the core 

of the rod but at a magnification of 500×. Figure 29 highlights the bands that alternate between 

tempered martensite/bainite and ferrite/pearlite zones. 

Figure 28. Photo. Micrograph near thread root etched with Marshall’s reagent at

500× magnification.
32

Figure 29. Photo. Micrograph near rod center etched with Marshall’s reagent

500× magnification.

Another portion of the large cross section was etched with 10-percent potassium metabisulfite, a

tint etchant that is commonly used in color metallography. Figure 30 shows a micrograph taken 

near the thread root viewed with polarized light at a magnification of 500× with the sample 

etched in 10-percent potassium metabisulfite. Figure 31 is a similar micrograph but was captured 

near the center of the rod.

The dark blue colored microstructure, which is present in nearly all of figure 30, is tempered 

martensite and possibly some bainite. This same microstructure is also present in figure 31 but in 

a much smaller amount. There is also a region of untempered martensite present, which is shown 

in brown. Although not extremely common, there are a few streaks of untempered martensite 

scattered throughout the rod core. In addition, a combination of ferrite and pearlite is also present

and is shown in the light blue areas. The microstructure near the rod core contains multiple 

phases but the microstructure near the thread roots is mostly tempered martensite suggests that 

something was awry with the heat treatment likely not allowing for complete transformation in 

the core.
33

Figure 30. Photo. Micrograph near thread root etched with 10-percent potassium 

metabisulfite at 500× magnification.

Figure 31. Photo. Micrograph near rod core etched with 10-percent potassium 

metabisulfite at 500× magnification.
34 

In addition to examining the microstructure of the rod, the threads were also inspected to 

determine how they were formed. The threads were inspected using the small cross section 

shown in figure 6. These sections were mounted, ground, and polished using the same procedure 

as used for the large cross sections. These small samples were etched with a 2-percent nital 

solution. Figure 32 shows a macrograph of a thread from one of the samples with two smaller 

micrographs embedded, taken at the thread root and crest, overlaid on the macrograph. 

The zinc coating applied during the galvanizing process can clearly be seen in both the 

macrograph and micrographs. A shallow band with a different morphology than the base metal 

can be seen near the surface of the root and thread diagonal. The band is approximately 0.006 to 

0.010 inches deep and appears to be a compressed form of the base metal microstructure 

indicating cold work. Because the cold working is limited to just the surface of the thread and the 

overall absence of flow lines within the entire thread, it suggests these threads were cut in lieu of

rolled. In addition, it is also obvious that the threads were cut after heat treatment; if the threads 

had been cut before heat treating, the microstructure would have been uniform all the way to the 

thread surface. 

Figure 32. Photo. Macrograph of thread with micrograph overlays taken at thread root 

and crest, etched with 2-percent nital.

Figure 33 more clearly shows the laminated appearance of the compressed microstructures in the 

cold worked zone. The figure also shows what the authors of this report refer to as 

delaminations, which were observed frequently in many threads analyzed. These delaminations 

were shallow and were contained within the cold work region. According to the ASTM F788 
35

standard, they are acceptable discontinuities that form as a result of thread forming because they 

are not aligned perpendicular to the longitudinal axis of the rod and their depth was very

shallow.

(16)

Figure 33. Photo. Micrograph of typical delamination at thread surface etched with 

2-percent nital at 500× magnification.

37

CHAPTER 4. CONCLUSIONS

The results of the mechanical, chemical, and microstructural analyses lead to the following 

conclusions:

• The material did not fully meet the requirements of the ASTM A354 grade BD standard, 

with strict interpretation.

(2) However, that statement needs some qualification because 

some of the material may be deemed acceptable within the vagueness of the ASTM 

standards and how it may be interpreted. For instance, the tensile testing performed 

conformed to the yield and tensile strength requirements of ASTM A354; however, some 

elongation values and reduction in areas did not conform, and some may judge that 

acceptable because strength requirements were met. As for hardness, the ASTM F606 

standard is not clear where hardness should be measured, and in the results collected for 

both samples in this report, non-conformance could be found, depending on the location 

and number of samples collected.(7)

• The impact toughness of the samples showed variation through the cross section, with the 

surface region showing the largest values of toughness, then decreasing as testing moved 

into the core of the rods. Each of the samples also showed little difference between the 

upper and lower shelves of energy where the upper shelf was on the order of 30 ft-lb, and 

the lower shelf was about 10 ft-lb. Each also showed a wide temperature transition range 

where the lower shelf was about -60 °F and the upper shelf was in excess of 120 °F. 

• The chemical analysis found that one of the four specimens did not meet the requirements 

of ASTM A322 grade 4140, which was the grade used by the manufacturer of the anchor

rods. However, all four specimens did meet the chemical requirements of ASTM A354, 

which is less stringent than ASTM A322. Chemical samples were taken near the surface 

and the core; there was no evidence of gross differences between the two locations,

indicating that the steel chemistry was uniform through the rod.

• No indications of preexisting crack-like discontinuities (perpendicular to the longitudinal 

axis of the rod) could be found in the thread roots of the threaded rod. This was 

confirmed using fluorescent wet magnetic particles on the entire threaded rod portion and 

also using red dye penetrant on a cross section of the threaded rod. Self-contained 

delaminations were observed on the threads under high magnification but these were 

acceptable discontinuities as defined in ASTM F788.

(16)

• Something went awry with the hardening process, leading to a nonuniformly hardened 

cross section based on the mechanical test results and metallography performed. This

observation is mainly applicable to the threaded sample, but is assumed to extend to the 

unthreaded sample because the mechanical test results were similar. The hardness, 

tensile, and impact toughness all showed a variation in properties between the surface of 

the rod and the core. To extend this further, the hardness also showed that the variation 

was not just across the diameter of the rod—that variation also occurred around the entire

rod cross section. The metallography showed that the outer third of the rod had achieved 

uniform quench and tempered microstructures, but it was not uniform in the core. The 
38

core of the rod contained a high amount of ferrite and pearlite, which is softer and not as 

strong as the tempered martensite that is expected to be there. This result points to 

problems that may have occurred during the hardening process, but no conclusions can be 

drawn as to what they were. 
39

CHAPTER 5. RECOMMENDATIONS

The following recommendations should be presented to ASTM International for consideration by

the F16 committee on fasteners:

1. Consider clarification of the intent of hardness measurements in the ASTM A354 and 

F606 standards so that more informed interpretation of material tests can be made. The 

specimens analyzed for this report were found to have variable properties across the 

diameter of the rods, and no ASTM quality control measures could account for that

result. Because hardening variation through the cross section is a possibility, especially 

in larger diameter threaded connectors, consider the inclusion of radial traverses and 

range of variation from surface to core for products over a certain diameter.

2. Consider the inclusion of supplemental toughness requirements for ASTM A354 that 

would establish a toughness number and sampling regime for the hardened product.

3. Consider additional quality control measures with ASTM A354 that would assure 

more complete transformation to martensite throughout the rod during heat treatment.

41

APPENDIX A. TABLES OF HARDNESS TESTING RESULTS

This appendix contains two tables of data representing the raw hardness measurements taken on 

the unthreaded and threaded rod cross sections. The location numbers in the table correlate to 

those shown in figure 11 and figure 12, but additional columns are provided in each table to 

represent the polar coordinates of each measurement point.

Table 3. Rockwell C hardness results for unthreaded sample.

Location

Rockwell C 

Hardness 

Value

Polar Coordinate 

Radius

(inches)

Polar Coordinate 

Angle

(degrees)

1 38.05 1.420 0

2 37.06 1.420 15

3 36.94 1.420 30

4 38.33 1.420 45

5 37.87 1.420 60

6 38.06 1.420 75

7 37.81 1.420 90

8 37.33 1.420 105

9 37.51 1.420 120

10 37.74 1.420 135

11 37.81 1.420 150

12 37.32 1.420 165

13 37.56 1.420 180

14 37.86 1.420 195

15 37.47 1.420 210

16 38.17 1.420 225

17 38.64 1.420 240

18 38.22 1.420 255

19 39.03 1.420 270

20 38.07 1.420 285

21 38.02 1.420 300

22 38.11 1.420 315

23 37.44 1.420 330

24 38.33 1.420 345

25 37.17 1.295 0

26 37.48 1.295 15

27 37.89 1.295 30

28 38.50 1.295 45

29 36.74 1.295 60

30 36.22 1.295 75

31 36.57 1.295 90

32 37.21 1.295 105

33 38.88 1.295 120
42

Location

Rockwell C 

Hardness 

Value

Polar Coordinate 

Radius

(inches)

Polar Coordinate 

Angle

(degrees)

34 38.13 1.295 135

35 36.95 1.295 150

36 36.60 1.295 165

37 37.00 1.295 180

38 38.39 1.295 195

39 37.58 1.295 210

40 37.86 1.295 225

41 36.95 1.295 240

42 36.54 1.295 255

43 36.49 1.295 270

44 36.82 1.295 285

45 37.88 1.295 300

46 38.34 1.295 315

47 36.74 1.295 330

48 36.48 1.295 345

49 37.99 1.170 0

50 38.64 1.170 15

51 37.39 1.170 30

52 37.21 1.170 45

53 36.82 1.170 60

54 35.75 1.170 75

55 36.43 1.170 90

56 38.25 1.170 105

57 38.73 1.170 120

58 38.81 1.170 135

59 38.66 1.170 150

60 38.00 1.170 165

61 38.28 1.170 180

62 38.28 1.170 195

63 38.23 1.170 210

64 38.78 1.170 225

65 37.47 1.170 240

66 36.52 1.170 255

67 37.05 1.170 270

68 38.04 1.170 285

69 37.36 1.170 300

70 39.06 1.170 315

71 37.84 1.170 330

72 38.12 1.170 345

73 37.62 1.045 0

74 37.50 1.045 15

75 38.64 1.045 30
43

Location

Rockwell C 

Hardness 

Value

Polar Coordinate 

Radius

(inches)

Polar Coordinate 

Angle

(degrees)

76 37.44 1.045 45

77 38.30 1.045 60

78 37.89 1.045 75

79 37.75 1.045 90

80 37.64 1.045 105

81 39.47 1.045 120

82 37.35 1.045 135

83 38.30 1.045 150

84 37.83 1.045 165

85 38.12 1.045 180

86 36.06 1.045 195

87 38.15 1.045 210

88 37.64 1.045 225

89 38.56 1.045 240

90 37.12 1.045 255

91 37.58 1.045 270

92 36.04 1.045 285

93 37.22 1.045 300

94 37.74 1.045 315

95 38.64 1.045 330

96 38.43 1.045 345

97 36.65 0.920 0

98 37.35 0.920 15

99 35.99 0.920 30

100 38.10 0.920 45

101 38.25 0.920 60

102 37.45 0.920 75

103 37.28 0.920 90

104 36.41 0.920 105

105 37.18 0.920 120

106 36.16 0.920 135

107 38.14 0.920 150

108 35.63 0.920 165

109 35.62 0.920 180

110 36.06 0.920 195

111 35.19 0.920 210

112 36.17 0.920 225

113 37.04 0.920 240

114 37.29 0.920 255

115 35.01 0.920 270

116 36.54 0.920 285

117 35.74 0.920 300
44

Location

Rockwell C 

Hardness 

Value

Polar Coordinate 

Radius

(inches)

Polar Coordinate 

Angle

(degrees)

118 35.87 0.920 315

119 36.76 0.920 330

120 36.40 0.920 345

121 36.04 0.795 0

122 37.02 0.795 15

123 36.77 0.795 30

124 35.24 0.795 45

125 35.79 0.795 60

126 36.23 0.795 75

127 35.50 0.795 90

128 37.58 0.795 105

129 37.79 0.795 120

130 36.84 0.795 135

131 37.22 0.795 150

132 36.37 0.795 165

133 34.15 0.795 180

134 35.12 0.795 195

135 34.63 0.795 210

136 35.53 0.795 225

137 35.58 0.795 240

138 36.87 0.795 255

139 35.73 0.795 270

140 35.01 0.795 285

141 32.32 0.795 300

142 34.96 0.795 315

143 36.60 0.795 330

144 37.17 0.795 345

145 38.74 0.670 0

146 36.48 0.670 15

147 38.38 0.670 30

148 35.56 0.670 45

149 37.42 0.670 60

150 36.18 0.670 75

151 37.01 0.670 90

152 37.22 0.670 105

153 35.89 0.670 120

154 34.21 0.670 135

155 34.9 0.670 150

156 34.16 0.670 165

157 34.20 0.670 180

158 34.63 0.670 195

159 31.87 0.670 210
45

Location

Rockwell C 

Hardness 

Value

Polar Coordinate 

Radius

(inches)

Polar Coordinate 

Angle

(degrees)

160 34.22 0.670 225

161 33.95 0.670 240

162 33.03 0.670 255

163 33.24 0.670 270

164 34.31 0.670 285

165 33.17 0.670 300

166 33.69 0.670 315

167 35.18 0.670 330

168 36.26 0.670 345

169 35.37 0.545 0

170 32.37 0.545 15

171 34.93 0.545 30

172 34.85 0.545 45

173 34.39 0.545 60

174 36.66 0.545 75

175 34.82 0.545 90

176 34.92 0.545 105

177 32.99 0.545 120

178 33.04 0.545 135

179 33.81 0.545 150

180 32.16 0.545 165

181 33.29 0.545 180

182 32.00 0.545 195

183 32.69 0.545 210

184 33.16 0.545 225

185 32.51 0.545 240

186 33.20 0.545 255

187 32.95 0.545 270

188 33.69 0.545 285

189 33.09 0.545 300

190 32.52 0.545 315

191 33.50 0.545 330

192 34.14 0.545 345

193 33.42 0.420 0

194 33.85 0.420 15

195 30.79 0.420 30

196 33.83 0.420 45

197 32.33 0.420 60

198 34.30 0.420 75

199 31.32 0.420 90

200 31.80 0.420 105

201 31.63 0.420 120
46

Location

Rockwell C 

Hardness 

Value

Polar Coordinate 

Radius

(inches)

Polar Coordinate 

Angle

(degrees)

202 32.36 0.420 135

203 33.37 0.420 150

204 30.53 0.420 165

205 32.13 0.420 180

206 31.89 0.420 195

207 31.57 0.420 210

208 32.52 0.420 225

209 35.73 0.420 240

210 32.29 0.420 255

211 33.07 0.420 270

212 33.22 0.420 285

213 32.84 0.420 300

214 30.99 0.420 315

215 31.69 0.420 330

216 32.58 0.420 345

217 29.50 0.295 0

218 31.90 0.295 30

219 31.16 0.295 60

220 32.10 0.295 90

221 31.44 0.295 120

222 31.87 0.295 150

223 31.45 0.295 180

224 32.31 0.295 210

225 29.68 0.295 240

226 32.40 0.295 270

227 32.05 0.295 300

228 30.98 0.295 330

229 33.05 0.170 0

230 30.71 0.170 45

231 31.48 0.170 90

232 31.40 0.170 135

233 28.97 0.170 180

234 31.34 0.170 225

235 29.34 0.170 270

236 29.33 0.170 315

237 34.39 0.000 0
47

Table 4. Rockwell C hardness results for threaded sample.

Location

Rockwell C 

Hardness 

Value

Polar Coordinate 

Radius

(inches)

Polar Coordinate 

Angle

(degrees)

1 37.13 1.213 0

2 38.29 1.213 15

3 37.20 1.213 30

4 37.53 1.213 45

5 36.13 1.213 60

6 36.16 1.213 75

7 36.48 1.213 90

8 37.75 1.213 105

9 37.62 1.213 120

10 37.72 1.213 135

11 36.87 1.213 150

12 36.72 1.213 165

13 37.47 1.213 180

14 37.60 1.213 195

15 36.97 1.213 210

16 35.59 1.213 225

17 35.43 1.213 240

18 35.53 1.213 255

19 37.16 1.213 270

20 38.45 1.213 285

21 38.41 1.213 300

22 38.50 1.213 315

23 38.23 1.213 330

24 37.75 1.213 345

25 37.97 1.088 0

26 38.30 1.088 15

27 37.57 1.088 30

28 37.60 1.088 45

29 37.26 1.088 60

30 37.01 1.088 75

31 37.13 1.088 90

32 37.12 1.088 105

33 37.40 1.088 120

34 37.97 1.088 135

35 37.75 1.088 150

36 37.86 1.088 165

37 36.58 1.088 180

38 36.78 1.088 195

39 36.79 1.088 210

40 36.62 1.088 225
48

Location

Rockwell C 

Hardness 

Value

Polar Coordinate 

Radius

(inches)

Polar Coordinate 

Angle

(degrees)

41 36.56 1.088 240

42 36.48 1.088 255

43 37.17 1.088 270

44 36.86 1.088 285

45 38.59 1.088 300

46 38.62 1.088 315

47 38.07 1.088 330

48 38.81 1.088 345

49 38.09 0.963 0

50 37.76 0.963 15

51 37.52 0.963 30

52 38.51 0.963 45

53 37.98 0.963 60

54 36.50 0.963 75

55 37.55 0.963 90

56 36.05 0.963 105

57 37.55 0.963 120

58 37.87 0.963 135

59 37.20 0.963 150

60 36.12 0.963 165

61 34.38 0.963 180

62 35.29 0.963 195

63 36.05 0.963 210

64 36.70 0.963 225

65 36.05 0.963 240

66 36.88 0.963 255

67 36.85 0.963 270

68 34.79 0.963 285

69 35.76 0.963 300

70 37.47 0.963 315

71 37.16 0.963 330

72 37.63 0.963 345

73 34.04 0.838 0

74 35.79 0.838 15

75 36.83 0.838 30

76 37.52 0.838 45

77 36.56 0.838 60

78 36.78 0.838 75

79 36.66 0.838 90

80 36.69 0.838 105

81 35.51 0.838 120

82 36.33 0.838 135
49

Location

Rockwell C 

Hardness 

Value

Polar Coordinate 

Radius

(inches)

Polar Coordinate 

Angle

(degrees)

83 35.23 0.838 150

84 37.05 0.838 165

85 34.86 0.838 180

86 34.20 0.838 195

87 34.73 0.838 210

88 34.72 0.838 225

89 35.65 0.838 240

90 33.98 0.838 255

91 34.09 0.838 270

92 34.75 0.838 285

93 35.79 0.838 300

94 35.68 0.838 315

95 38.10 0.838 330

96 36.99 0.838 345

97 37.20 0.713 0

98 35.55 0.713 15

99 36.69 0.713 30

100 35.48 0.713 45

101 36.68 0.713 60

102 36.53 0.713 75

103 36.48 0.713 90

104 37.64 0.713 105

105 37.35 0.713 120

106 36.03 0.713 135

107 36.25 0.713 150

108 36.26 0.713 165

109 32.91 0.713 180

110 32.92 0.713 195

111 32.97 0.713 210

112 33.11 0.713 225

113 34.66 0.713 240

114 34.23 0.713 255

115 33.70 0.713 270

116 32.11 0.713 285

117 33.45 0.713 300

118 35.65 0.713 315

119 35.89 0.713 330

120 35.89 0.713 345

121 33.39 0.588 0

122 32.76 0.588 15

123 36.08 0.588 30

124 33.98 0.588 45
50

Location

Rockwell C 

Hardness 

Value

Polar Coordinate 

Radius

(inches)

Polar Coordinate 

Angle

(degrees)

125 36.56 0.588 60

126 35.94 0.588 75

127 35.95 0.588 90

128 34.02 0.588 105

129 33.06 0.588 120

130 35.13 0.588 135

131 34.84 0.588 150

132 34.54 0.588 165

133 33.03 0.588 180

134 33.18 0.588 195

135 32.22 0.588 210

136 33.19 0.588 225

137 33.51 0.588 240

138 33.68 0.588 255

139 33.29 0.588 270

140 32.87 0.588 285

141 32.34 0.588 300

142 32.26 0.588 315

143 32.02 0.588 330

144 34.31 0.588 345

145 30.60 0.463 0

146 32.56 0.463 15

147 33.35 0.463 30

148 33.57 0.463 45

149 33.74 0.463 60

150 34.35 0.463 75

151 32.92 0.463 90

152 31.15 0.463 105

153 34.23 0.463 120

154 33.96 0.463 135

155 32.31 0.463 150

156 33.16 0.463 165

157 31.64 0.463 180

158 31.18 0.463 195

159 33.46 0.463 210

160 32.46 0.463 225

161 35.31 0.463 240

162 33.74 0.463 255

163 32.67 0.463 270

164 32.54 0.463 285

165 30.45 0.463 300

166 30.98 0.463 315
51

Location

Rockwell C 

Hardness 

Value

Polar Coordinate 

Radius

(inches)

Polar Coordinate 

Angle

(degrees)

167 30.86 0.463 330

168 30.70 0.463 345

169 31.80 0.338 0

170 32.74 0.338 15

171 29.47 0.338 30

172 33.97 0.338 45

173 30.99 0.338 60

174 30.31 0.338 75

175 32.65 0.338 90

176 32.52 0.338 105

177 32.28 0.338 120

178 30.32 0.338 135

179 31.02 0.338 150

180 30.81 0.338 165

181 31.13 0.338 180

182 30.75 0.338 195

183 31.75 0.338 210

184 31.85 0.338 225

185 32.93 0.338 240

186 32.54 0.338 255

187 31.61 0.338 270

188 30.53 0.338 285

189 31.67 0.338 300

190 30.87 0.338 315

191 30.37 0.338 330

192 32.68 0.338 345

193 29.71 0.213 0

194 32.25 0.213 30

195 29.88 0.213 60

196 29.32 0.213 90

197 30.02 0.213 120

198 34.25 0.213 150

199 29.61 0.213 180

200 31.86 0.213 210

201 31.02 0.213 240

202 32.55 0.213 270

203 30.39 0.213 300

204 31.84 0.213 330

205 31.98 0.000 0

53

APPENDIX B. TABLES OF CHARPY TESTING RESULTS

This appendix contains two tables of data representing the raw Charpy impact toughness 

measurements taken on the unthreaded and threaded rod cross sections. The specimen 

identifications in the table correlate to those shown in figure 5 and figure 6. Additional columns 

in the table represent the test temperature, toughness value, lateral expansion measurement, 

percent-shear area, and distance from the specimen notch root to the surface of the rod.

Table 5. Raw data unthreaded sample Charpy specimens.

Specimen

Test 

Temperature

(°F)

Impact 

Energy

(ft-lb)

Percent 

Shear

Lateral 

Expansion

(inches)

Distance from 

Notch to Rod 

Surface

(inches)

A1 132.4 55.8 39 0.0191 0.14

A2 -30.1 — 11 0.008 0.14

A3 38.5 16.75 16 0.0043 0.14

A4 -60.0 15 8 0.0059 0.14

A5 92.5 28 36 0.014 0.14

A6 67.1 23.25 29 0.0103 0.14

A7 -0.4 17 14 0.0067 0.14

A8 67.1 22.75 31 0.0114 0.14

A9 -60.5 14.75 7 0.0053 0.14

A0 199.4 35.25 41 0.0213 0.14

B1 -0.2 12.5 9 0.004 0.84

B2 0.5 12.75 9 0.0048 0.84

B3 -61.1 9 < 5 0.0037 0.84

B4 199.9 31.5 33 0.0171 0.84

B5 -60.5 7.25 < 5 0.002 0.84

B7 132.1 31.5 38 0.0149 0.14

B8 0.3 14.5 15 0.0055 0.14

B9 -59.3 12.5 8 0.0043 0.14

B0 200.5 36.25 45 0.0183 0.14

C1 -34.5 14.5 12 0.0074 0.14

C2 33.6 28 38 0.013 0.14

C3 -34.7 15.5 13 0.0051 0.14

C4 33.6 24.5 38 0.0117 0.14

C5 -33.6 14.25 12 0.0045 0.14

C6 -17.7 16 15 0.0061 0.14

C7 56 30 38 0.0146 0.14

C8 3.5 20 23 0.0088 0.14

C9 3.3 20.5 27 0.0096 0.14

C0 21.5 21.25 30 0.0124 0.38
54

Specimen

Test 

Temperature

(°F)

Impact 

Energy

(ft-lb)

Percent 

Shear

Lateral 

Expansion

(inches)

Distance from 

Notch to Rod 

Surface

(inches)

D1 19.3 22 28 0.0128 0.14

D2 70.2 17.25 19 0.0081 0.60

D3 130.8 22.25 34 0.0122 0.84

D4 -60.7 11.75 5 0.0041 0.84

D5 67.6 17.5 25 0.0094 0.84

D6 130.6 26 32 0.0152 0.84

D7 68.4 18 17 0.0072 0.84

D8 0.3 9 9 0.0035 0.84

D9 68.5 16.5 23 0.0087 0.84

D0 68.9 14.5 26a 0.0075a 1.5

E1 69.4 16.5 18 0.0093 1.5

— Indicates ignored specimen; energy gauge not reset between specimens. a

Measurements are based on only one fracture face because the other half of the broken specimen was used for 

chemical analysis.

Table 6. Raw data for threaded sample Charpy specimens.

Specimen

Test 

Temperature

(°F)

Impact 

Energy

(ft-lb)

Percent 

Shear

Lateral 

Expansion

(inches)

Distance from 

Notch to Rod 

Surface

(inches)

E2 0.3 13.5 10 0.0057 0.33

E3 130.3 25 31 0.0151 0.33

E4 -0.6 12.25 10 0.0041 0.33

E5 70.0 17.25 28 0.0083 0.33

E6 200.3 34.5 31 0.0222 0.33

E7 -60 11.5 6 0.0105 0.33

E8 131.4 23.75 35 0.0117 0.33

E9 -61.1 12.25 < 5 0.0051 0.33

E0 -59.3 12.5 < 5 0.0045 0.33

F1 69.8 18.5 28a 0.0065a 0.33

F2 -60.3 8.5 < 5 0.0025 1.5

F3 0.9 12.5 8 0.0099 1.5

F4 68.4 12.75 18a 0.005a 1.5

F5 131.2 19.5 22 0.0121 1.5

F6 200.5 33.5 38 0.023 1.5

F7 -30.6 10.25 < 5 0.0041 1.5 a

Measurements are based on only one fracture face because the other half of the broken specimen was used for 

chemical analysis.
55

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HRDI-40/08-15(WEB)E