PUBLICATIONS

.^T OF c NBS SPECIAL PUBLICATION 260-86

U.S. DEPARTMENT OF COMMERCE/National Bureau of Standards

Standard Reference Materials:

A Standard Reference Material

Containing 2.5 Percent

Austenite (SRM 488)

260-3G

1933
NATIONAL BUREAU OF STANDARDS

The National Bureau of Standards' was established by an act ol Congress on March 3, 1901. The Bureau's overall goal is to strengthen and advance the Nation's science and technology and facilitate their effective application for public benefit. To this end, the Bureau conducts

research and provides: (1) a basis for the Nation's physical measurement system, (2) scientific and technological services for industry and government, (3) a technical basis for equity in trade, and (4) technical services to promote public safety. The Bureau's technical work is per- formed by the National Measurement Laboratory, the National Engineering Laboratory, and

the Institute for Computer Sciences and Technology. THE NATIONAL MEASUREMENT LABORATORY provides the national system of

physical and chemical and materials measurement; coordinates the system with measurement

systems of other nations and furnishes essential services leading to accurate and uniform

physical and chemical measurement throughout the Nation's scientific community, industry, and commerce; conducts materials research leading to improved methods of measurement,

standards, and data on the properties of materials needed by industry, commerce, educational

institutions, and Government; provides advisory and research services to other Government

agencies; develops, produces, and distributes Standard Reference Materials; and provides

calibration services. The Laboratory consists of the following centers: Absolute Physical Quantities2 — Radiation Research — Chemical Physics —

Analytical Chemistry — Materials Science THE NATIONAL ENGINEERING LABORATORY provides technology and technical ser- vices to the public and private sectors to address national needs and to solve national problems; conducts research in engineering and applied science in support of these efforts; builds and maintains competence in the necessary disciplines required to carry out this research and technical service; develops engineering data and measurement capabilities; provides engineering measurement traceability services; develops test methods and proposes

engineering standards and code changes; develops and proposes new engineering practices; and develops and improves mechanisms to transfer results of its research to the ultimate user. The Laboratory consists of the following centers:

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research and provides scientific and technical services to aid Federal agencies in the selection, acquisition, application, and use of computer technology to improve effectiveness and economy in Government operations in accordance with Public Law 89-306 (40 U.S.C. 759), relevant Executive Orders, and other directives; carries out this mission by managing the Federal Information Processing Standards Program, developing Federal ADP standards

guidelines, and managing Federal participation in ADP voluntary standardization activities; provides scientific and technological advisory services and assistance to Federal agencies; and

provides the technical foundation for computer-related policies of the Federal Government. The Institute consists of the following centers: Programming Science and Technology — Computer Systems Engineering.

'Headquarters and Laboratories at Gaithersburg, MD, unless otherwise noted; mailing address Washington, DC 20234. 'Some divisions within the center are located at Boulder, CO 80303.
JNATIONAL BUREAU ©F STANDARDS

LIBRARY Standard Reference Materials:

A Standard Reference Material Containing

2.5 Percent Austenite (SRM 488)

G.E. Hicho and E.E. Eaton

Fracture and Deformation Division Center for Materials Science

National Measurement Laboratory

National Bureau of Standards Washington, DC 20234

U.S. DEPARTMENT OF COMMERCE, Malcolm Baldrige, Secretary

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director Issued December 1983

C .9-
Library of Congress Catalog Card Number: 83-600613

National Bureau of Standards Special Publication 260-86

Natl. Bur. Stand. (U.S.), Spec. Publ. 260-86, 23 pages (Dec. 1983)

CODEN: XNBSAV

U.S. GOVERNMENT PRINTING OFFICE WASHINGTON: 1983

For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, DC 20402

Price (Add 25 percent for other than U.S. mailing)
PREFACE

Standard Reference Materials (SRM's) as defined by the National Bureau of Standards are wel 1 -characterized materials

produced in quantity and certified for one or more physical

or chemical properties. They are used to assure the accuracy

and compatibility of measurements throughout the Nation.

SRM's are widely used as primary standards in many diverse

fields in science, industry, and technology, both within the United States and throughout the world. They are also used extensively in the fields of environmental and clinical analysis. In many applications, traceability of quality control

and measurement processes to the national measurement system

are carried out through the mechanism and use of SRM's. For many of the Nation's scientists and technologists it is therefore of more than passing interest to know the details

of the measurements made at NBS in arriving at the certified

values of the SRM's produced. An NBS series of papers, of which this publication is a member, called the NBS Special Publication - 260 Series , is reserved for this purpose.

This 260 Series is dedicated to the dissemination of information on different phases of the preparation, measurement, certification and use of NBS-SRM's. In general, much

more detail will be found in these papers than is generally

allowed, or desirable, in scientific journal articles. This enables the user to assess the validity and accuracy of the measurement processes employed, to judge the statistical

analysis, and to learn details of techniques and methods

utilized for work entailing the greatest care and accuracy. These papers also should provide sufficient additional infor- mation not found on the certificate so that new applications

in diverse fields not foreseen at the time the SRM was orig- inally issued will be sought and found. Inquiries concerning the technical content of this paper should be directed to the authors. Other questions concerned

with the availability, delivery, price, and so forth will receive prompt attention from:

Office of Standard Reference Materials

National Bureau of Standards Washington, D.C. 20234

Stanley D. Rasberry

Acting Chief Office of Standard Reference Materials
OTHER NBS PUBLICATIONS IN THIS SERIES

Catalog of NBS Standard Reference

(1981-83 edition).

R. W. Seward, ed., NBS Spec. Publ. 260 (November 1981)

.

Michaelis, R. E. and Wyman, L. L.

,

Standard Reference Materials: Preparation of White Cast Iron Spectrochemical Standards. NBS

Misc. Publ. 260-1 (June 1964) C0M74-11061**

Michaelis, R. E., Wyman, L. L.

,

and Flitsch, R., Standard Reference Materials: Prepararation of NBS Copper-Base

Spectrochemical Standards.

NBS Misc. Publ. 260-2 (October

1964) C0M74-11063**

Michaelis, R. E. , Yakowitz, H., and Moore, G. A., Standard Reference Materials: Metal

lographic Characterization of Steel Standard. NBS Misc. Publ. 260-3 (October 1964) C0M74-11060**

Hague, J. L. Mears, T. W. , and Michaelis, R. E. , Standard Reference Materials: Sources

of Information. NBS Misc. Publ. 260-4 (February 1965) C0M74-11059

Alvarez, R. and Flitsch, R., Standard Reference Materials: Accuracy of Solution X-Ray Spectrometric Analysis of Copper-Base Alloys. NBS Misc.

Publ. 260-5 (March 1965) PB168068**

Shultz, J. I., Standard Reference

Materials: Methods for the Chemical Analysis of White Cast

Iron Standards. NBS Misc. Publ. 260-6 (July 1975) C0M74-11068**

Bell, R. K. , Standard Reference

Materials: Methods for the Chemical Analysis of NBS CopperBase Spectrochemical Standards.

NBS Misc. Publ. 260-7 (October 1965) C0M74-11067**

Richmond, M. S., Standard Reference

Materials: Analysis of Uranium

Concentrates at the National Bureau of Standards. NBS Misc.

Publ. 260-8 (December 1965) C0M74-11066**

Anspach, S. C, Cavallo, L. M.

,

Garfinkel, S. B., Hutchinson,

J. M. R. and Smith, C. N., Standard Reference Materials:

Half Lives of Materials Used in the Preparation of Standard Reference Materials of Nineteen Radioactive Nuclides Issued by

the National Bureau of Standards

NBS Misc. Publ. 260-9 (November

1965) C0M74-11065**

Yakowitz, H., Vieth, D. L., Heinrich,

K. F. J., and Michaelis, R. E., Standard Reference Materials: Homogeneity Characterization on NBS Spectrometric Standards II: Cartridge Brass and Low-Alloy Steel,

NBS Misc. Publ. 260-10 (December

1965) C0M74-11064**

Napolitano, A. and Hawkins, E. G., Standard Reference Materials: Viscosity of Standard Lead-Silica

Glass. NBS Misc. Publ. 260-11 (November 1966) NBS Misc. Publ. 260-11**

Yakowitz, H., Vieth, D. L., and Michaelis, R. E., Standard Reference

Materials: Homogeneity

Characterization of NBS Spectrometric Standards III: White Cast

Iron and Stainless Steel Powder

Compact. NBS Misc. Publ. 260-12**

Spijkerman, J. L., Snediker, D. K., Ruegg, F. C, and DeVoe, J. R., Standard Reference Materials: Mossbauer Spectroscopy Standard for

the Chemical Shift Compounds.

NBS Misc. Publ. 260-13** (July

1967) Menis, 0. and Sterling, J. T., Standard Reference Materials: Determination of Oxygen in Ferrous Materials - SRM 1090, 1091, and 1092. NBS Spec. Publ. 260-14**

(September 1966) Passaglia, E. and Shouse, P. J., Standard Reference Materials: Recommended Method of Use of Standard Light-Sensitive Paper for Calibrating Carbon Arcs Used in Testing Textiles for Colorf astness

to Light. NBS Misc. Publ. 260-15

(June 1967) (Replaced by NBS Spec. 260-41.) Yakowitz, H., Michaelis, R. E. and Vieth, D. L., Standard Reference

Materials: Homogeneity Characterization of NBS Spectrometric Standards IV: Preparation and Microprobe Characterization of W-20% MO Alloy

Fabricated by Powder Metallurgical

Methods. NBS Spec. Publ. 260-16

(January 1969) C0M74-11062**

Catanzaro, E. J., Champion, C. E., Garner, E. L., Marinenko, G., Sappenfield, K . M. and Shields,

W. R., Standard Reference Materials:

Boric Acid: Isotopic and Assay

Standard Reference Materials. NBS Spec. Publ. 260-17 (February 1970)

Out of Print

iv
Geller, S. B., Mantek, P. A., and Cleveland, N. G. , Standard Reference

Materials: Calibration of NBS Secondary Standard Magnetic Tape (Computer Amplitude Reference)

Using the Reference Tape Amplitude Measurement "Process A.

NBS Spec. Publ . 260-18

(November 1969) (See NBS Spec. Publ. 260-29.)

Paule, R. C. and Mandel, J., Standard Reference Materials: Analysis of Interlaboratory Measurements on the Vapor Pressure of Gold (Certification of Standard Reference Material

745). NBS Spec. Publ. 260-19 (January 1970) PB190071**

Paule, R. C. and Mandel, J., Standard Reference Materials: Analysis of Interlaboratory Measurements on the Vapor Pressures of Cadmium and Silver.

NBS Spec. Publ. 260-21 (January 1971) C0M74-11359**

Yakowitz, H., Fiori , C. E., and Michaelis, R. E., Standard Reference

Materials: Homogeneity Characterization of Fe-3 Si Alloy. NBS Spec. Publ. 260-22 (February 1971) C0M74-11357**

Napolitano, A. and Hawkins, E. G., Standard Reference Materials: Viscosity of a Standard Borosilicate Glass. NBS Spec. Publ. 260-23

(December 1970) C0M71 -00157** Sappenfield, K. M. , Marinenko, 6. and Hague, J. L., Standard Reference

Materials: Comparison of Redox Standards, NBS Spec. Publ. 260-24

(January 1972) C0M72-50058**

Hicho, G. E., Yakowitz, H., Rasberry,

S. D., and Michaelis, R. E.

Standard Reference Materials: A Standard Reference Material Containing Nominally Four Percent

Austenite. NBS Spec. Publ. 260-25 (February 1971) C0M74 - 11 356** Martin, J. F., Standard Reference

Materials: National Bureau of Standards-US Steel Corporation

Joint Program for Determining

Oxygen and Nitrogen in Steel.

NBS Spec. Publ. 260-26 (February

1971) 85 cents* PB81176620

Garner, E. L., Machlan, L. A., and Shields, W. R., Standard Reference

Materials: Uranium Isotopic Standard Reference Materials. NBS Spec. Publ. 260-27 (April 1971) C0M74-11358**

Heinrich, K. F. J., Myklebust, R. L., Rasberry, S. D., and Michaelis,

R. E., Standard Reference Materials: Preparation and Evaluation of SRM's

481 and 482 Gold-Silver and Gold- Copper Alloys for Microanalysis.

NBS Spec. Publ. 260-28 (August 1971) C0M71-50365**

Geller, S. B., Standard Reference

Materials: Calibration of NBS Secondary Standard Magnetic Tape (Computer Amplitude Reference)

Using the Reference Tape Amplitude

Measurement "Process A-Model 2".

NBS Spec. Publ. 260-29 (June 1971) C0M71-50282

Gorozhanina, R. S., Freedman, A. Y., and Shaievitch, A. 6. (translated

by M. C. Selby), Standard Reference

Materials: Standard Samples Issued

in the USSR (A Translation from the Russian). NBS Spec. Publ. 260-30

(June 1971) C0M71-50283**

Hust, J. G. and Sparks, L. L. , Standard Reference Materials: Thermal Conducti vity of Electrolytic Iron SRM 734 from 4 to 300 K. NBS Spec.

Publ. 260-31 (November 1971) C0M71-50563**

Mavrodi neanu , R. and Lazar, J. W., Standard Reference Materials: Standard Quartz Cuvettes for High Accuracy Spectrophotometry. NBS Spec. Publ. 260-32 (December 1973)

55 cents* SN003-003-01213-1

Wagner, H. L., Standard Reference

Materials: Comparison of Original

and Supplemental SRM 705, Narrow Molecular Weight Distribution

Polystyrene. NBS Spec. Publ. 260-33 (May 1972) C0M72-50526**

Sparks, L. L. and Hust, J. G., Standard Reference Materials: Thermoelectric Voltage. NBS Spec. Publ. 260-34 (April 1972) C0M72-50371**

Sparks, L. L. and Hust, J. G., Standard Reference Materials:

Thermal Conductivity of Austenitic

Stainless Steel, SRM 735 from 5 to 280 K. NBS Spec. Publ. 260-35

(April 1972) 35 cents* C0M72-50368**
Cali, J. P., Mandel, J., Moore, L. J., and Young, D. S., Standard Reference

Materials: A Referee Method for the Determination of Calcium in Serum,

NBS SRM 915. NBS Spec. Publ. 260-36

(May 1972) C0M72-50527*

Shultz, J. I., Bell, R. K . , Rains,

T. C, and Menis, 0., Standard Reference Materials: Methods of Analysis of NBS Clay Standards.

NBS Spec. Publ. 260-37 (June 1972) C0M72-50692**

Richmond, J. C. and Hsia, J. J., Standard Reference Materials: Preparation and Calibration of Standards of Spectral Specular Reflectance. NBS Spec. Publ. 260-38 (May 1972) C0M72-50528**

Clark, A. F., Denson, V. A., Hust J. G., and Powell, R. L., Standard Reference Materials: The Eddy Current Decay Method for Resistivity

Characterization of High-Purity

Metals. NBS Spec. Publ. 260-39

(May 1972 C0M72-50529**

McAdie, H. G. , Garn, P. D., and Menis, 0., Standard Reference

Materials: Selection of Thermal Analysis Temperature Standards Through a Cooperative Study (SRM

758, 749, 760). NBS Spec Publ. 260-40 (August 1972) C0M72-50776**

Wood, L. A. and Shouse, P. J., Standard Reference Materials: Use

of Standard Light-Sensitive Paper for Calibrating Carbon Arcs Used in Testing Textiles for Colorf astness

to Light. NBS Spec. Publ. 260-41

(August 1972) C0M72-50775**

Wagner, H. L. and Verdier, P. H., eds., Standard Reference Materials: The Characterization of Linear Poly- ethylene, SRM 1475. NBS Spec. Publ. 260-42 (September 1972) C0M72-50944**

Yakowitz, H., Ruff, A. W., and Michaelis,

R. E., Standard Reference Materials: Preparation and Homogeneity Characterization of an Austenitic Iron-ChromiumNickel Alloy. NBS Spec. Publ. 260-43 (November 1972) C0M73-50760**

Schooley, J. F., Soulen, R. J., Jr., and Evans, G. A., Jr., Standard Reference

Materials: Preparation and Use of Superconduti ve Fixed Point Devices,

SRM 767. NBS Spec. Pub. 260-44

(December 1972) COM73-50037**

Greifer, B., Maienthal, E. J., Rains,

T. C, and Rasberry, S. D., Standard Reference Materials: Powdered Lead- Based Paint, SRM 1579. NBS Spec. Publ. 260-45 (March 1973) C0M73-50226**

Hust, J. G. and Giarratano, P. J., Standard Reference Materials: Thermal Conductivity and Electrical Resistivity

Standard Reference Materials: Austenitic Stainless Steel SRM's 735 and 798, from 4 to 1200 K. NBS Spec. Publ. 260-46 (March 1975) SN-003-003-

01278-5

Hust, J. G., Standard Reference Materials: Electrical Resistivity of Electrolytic

Iron, SRM 797, and Austenitic Stainless

Steel, SRM 798, from 5 to 280 K. NBS Spec. Publ. 260-47 (February 1974) C0M74-50176**

Mangum, B. W. and Wise, J. A., Standard Reference Materials: Description and Use of Precision Thermometers for the

for the Clinical Laboratory, SRM 933

and SRM 934. NBS Spec. Publ. 260-48

(May 1974) 60 cents* SN003-003-01278-5

Carpenter, B. S. and Reimer, G. M.

Standard Reference Materials Calibrated

Glass Standards for Fission Track Use. NBS Spec. Publ. 260-49 (November 1974) C0M74-51185

Hust, J. G. and Giarratano, P. J., Standard Reference Materials: Thermal Conductivity

and Electrical Resistivity Standard Reference Materials: Electrolytic Iron, SRM's 734 and 797 from 4 to 1000 K. NBS Spec. Publ. 260-50 (June 1975) $1.00* SN003-003-01425-7

Mavrodineanu, R. and Baldwin, J. R.

Standard Reference Materials: Glass Filters As a Standard for Spectro- photometry; Selection; Preparation; Certification; Use-SRM 930. NBS Spec. Publ. 260-51 (November 1975) $1.90* SN003-003-01481-8

Hust, J. G. and Giarratano, P. J., Standard Reference Materials: Thermal Conductivity and Electrical Resistivity

Standard Reference Materials 730 and 799, from 4 to 3000 K. NBS Spec. Publ. 260-52 (September 1975) $1.05* SN003-003-01464-8

Durst, R. A., Standard Reference Materials: Standardization of pH Measurements. NBS Spec. Publ. 260-53 (December 1975, Revised) $1.05 SN003-003-01551-2

Burke, R. W. and Mavrodineanu, R., Standard Reference Materials: Certification and Use of Acidic Potassium Dichromate

Solutions as an Ultraviolet Absorbance

Standard. NBS Spec. Publ. 260-54

(August 1977) $3.00* SN003-003-01828-7

Ditmars, D. A., Cezairliyan, A., Ishihara,

S., and Douglas, T. B., Standard Reference

Materials: Enthalpy and Heat Capacity: Molybdenum SRM 781, from 273 to 2800 K. NBS Spec. Publ. 260-55 (September 1977) $2.20* SN003-003-01836-8

vi
Powell, R. L., Sparks, L. L., and Hust,

J. G., Standard Reference Materials: Standard Thermocouple Materials, Pt.67: SRM 1967. NBS Spec. Publ. 260-56 (February 1978) $2.20* SN003-003-018864

Cali, J. P. and Plebanski , T., Guide to United States Reference Materials. NBS

Spec. Publ. 260-57 (February 1978) $2.20' PB 277173 Barnes, J. D. and Martin, G. M. , Standard Reference Materials: Polyester Film for Oxygen Gas Transmission Measurements,

SRM 1470. NBS Spec. Publ. 260-58 (June

1979) $2.00* SN003-003-02077

Chang, T. and Kahn, A. H., Standard Reference Materials: Electron Paramagnetic Resonance Intensity

Standard; SRM 2601. NBS Spec. Publ. 260-59 (August 1978) $2.30* SN003- 003-01975-5

Velapoldi, R. A., Paule, R. C, Schaffer,

R., Mandel, J., and Moody, J. R., Standard Reference Materials: A Reference Method for the Determination

of Sodium in Serum. NBS Spec. Publ. 260-60 (August 1978) $3.00 SN003-003- 01978-0

Verdier, P. H. and Wagner, H. L.

,

Standard Reference Materials: The Characterization of Linear Polyethylene

(SRM 1482, 1483, 1484). NBS Spec. Publ. 260-61 (December 1978) $1.70* SN003-003-02047-8

Soulen, R. J. and Dove, R. B., Standard Reference Materials: Temperature Reference Standard for Use Below 0.5 K (SRM 768). NBS Spec. Publ. 260-62

(April 1979) $2.30* SN003-003-02047-8

Velapoldi, R. A., Paule, R. C, Schaffer,

R., Mandel, J., Machlan, L. A., and Gramlich, J. W., Standard Reference

Materials: A Reference Method for the Determination of Potassium in Serum.

NBS Spec. Publ. 260-63 (May 1979) $3.75* SN003-003-02068

Velapoldi, R. A. and Mielenz, K. D., Standard Reference Materials: A Fluorescence Standard Reference

Material Quinine Sulfate Dihydrate

(SRM 936). NBS Spec. Publ. 260-64 (January 1980) $4.25* SN003-003-02148-2

Marinenko, R. B., Heinrich, K. F. J., and Ruegg, F. C, Standard Reference

Materials: Micro-Homogeneity Studies

of NBS Standard Reference Materials,

NBS Research Materials, and Other Related Samples. NBS Spec. Publ. 260-65 (September 1979) $3.50* SN003- 003-02114-1

Venable, w. H., Jr. and Eckerle, K. L., Standard Reference Materials: Didymium Glass Filters for Calibrating

the Wavelength Scale of Spectrophotometers (SRM 2009, 2010, 2013). NBS

Spec. Publ. 260-66 (October 1979) $3.50* SN003-003-02127-0

vii

Velapoldi, R. A., Paule, R. C, Schaffer,

R., Mandel, J., Murphy, T. J., and Gramlich, J. W. , Standard Reference

Materials: A Reference Method for the Determination of Chloride in Serum.

NBS Spec. Publ. 260-67 (November 1979) $3.75* SN003-003-02136-9

Mavrodi neanu , R. and Baldwin, J. R., Standard Reference Materials: Metal - On-Quartz Filters as a Standard Reference Material for Spectrophoto- metry-SRM 2031. NBS Spec. Publ. 260-68 (April 1980) $4.25* SN003-003- 02167-9

Velapoldi, R. A., Paule, R. C, Schaffer,

R., Mandel, J., Machlan, L. A., Garner,

E. L., and Rains, T. C, Standard Reference Materials: A Reference Method

for the Determination of Lithium in Serum. NBS Spec. Publ. 260-69 (July

1980) $4.25* SN003-003-02214-4

Marinenko, R. B. Bi ancani el lo , F., Boyer,

P. A., Ruff, A. W., DeRobertis, L., Standard Reference Materials: Preparation

and Characterization of an Iron-ChromiumNickel Alloy for Microanalysis. NBS Spec. Publ. 260-70 (May 1981) $2.60* SN003-003-02328-1

Seward, R. W. and Mavrodi neanu , R., Standard Reference Materials: Summary of the Clinical Laboratory

Standards Issued by the National Bureau of Standards. NBS Spec. Publ. 260-71 (November 1981) $6.50* SN003- 003-02381-7

Reeder, D. J., Coxon, B., Enagonio, D., Christensen, R. G., Schaffer, R., Howell , B. F., Paule, R. C, and Mandel, J., Standard Reference Materials:

SRM 900. Antiepilepsy Drug Level Assay

Standard. NBS Spec. Publ. 260-72

(June 1981) $4.25* SN003-003-02329-9

Interrante, C. G. and Hicho, G. E., Standard Reference Materials: A Standard Referenc3 Material Containing Nominally Fifteen Percent Austenite

(SRM 486). NBS Spec. Publ. 260-73 (January 1982) $2.75* SN003-003-02386-8

Marinenko, R. B., Standard Reference

Materials: Preparation and Characterization of K-411 and K-414

Mineral Glasses for Microanalysis:

SRM 470. NBS Spec. Publ. 260-74

(April 1982) $3.50 SN003-003-023-95-7

Weidner, V. R. and Hsia, J. J., Standard Reference Materials: Preparation and Calibration of First Surface Aluminum

Mirror Specular Reflectance Standards

(SRM 2003a). NBS Spec. Publ. '260-75 (May 1982) $3.75 SN003-003-023-99-0
Hicho, G. E. and Eaton, E. E., Standard Reference Materials: A Standard Reference Material Containing Nominally Five Percent Austenite

(SRM 485a). NBS Spec. Publ. 260-76

(August 1982) $3.50 SN003-003-024-33-3

Furukawa, G. T., Riddle, J. L. , Bigge,

W. G., and Pfieffer, E. R., Standard Reference Materials: Application of Some Metal SRM's as Thermometric Fixed

Points. NBS Spec. Publ. 260-77 (August

1982) $6.00 SN003-003-024-34-1

Hicho, G. E. and Eaton, E. E., Standard Reference Materials: Standard Reference Material Containing Nominally Thirty Percent Austenite (SRM 487).

NBS Spec. Publ. 260-78 (September 1982) $3.75 SN003-003-024-35-0

Richmond, J. C, Hsia, J. J., Weidner,

V. R., and Wilmering, D. B, Standard Reference Materials: Second Surface Mirror Standards of Specular Spectral Reflectance (SRM's 2023, 2024, 2025).

NBS Spec. Publ. 260-79 (October 1982) $4.50 SN003-003-024-47-3

Schaffer, R., Mandel, J., Sun, T., Cohen,

A., and Hertz, H. S., Standard Reference

Materials: Evaluation by an ID/MS Method of the AACC Reference Method for Serum Glucose. NBS Spec. Publ. 260-80

(October 1982) $4.75 SN003-003-024-43-1

Swyt, D. A., Standard Reference Materials:

A Look at Techniques for the Dimensional Calibration of Standard Microscopic

Particles. NBS Spec. Publ. 260-85 (September 1983) $5.50 SN003-003-025-

21-6

Hicho, G. E. and Eaton, E. E., Standard Reference Materials: A Standard Reference Material Containing Two

and One-Half Percent Austenite,

SRM 488. NBS Spec. Publ. 260-86

(In Press). Mangum, B. W. , Standard Reference

Materials: SRM 1969: Rubidium

Triple-Point - A Temperature Reference Standard Near 39.30 °C. NBS Spec. Publ. 260-87 (In Press).

* Send order with remittance to Superintendent of Documents, US Government Printing Office, Washington, DC 20402. Remittance

from foreign countries should include an additional one-fourth

of the purchase price for postage.

* May be ordered from: National Technical Information Services

(NTIS). Springfield, VA 22151.

Burke, R. W. and Mavrodi neanu, R. (NBS retired), Standard Reference Materials: Accuracy in Analytical Spectrophotometry.

NBS Spec. Publ. 260-81 (April 1983) $6.00 SN003-003-024-84-8

Weidner, V. R., Standard Reference

Materials: White Opal Glass Diffuse

Spectral Reflectance Standards for the Visible Spectrum (SRM's 2015 and 2016).

NBS Spec. Publ. 260-82 (April 1983). $3.75 SN003-003-024-89-9

Bowers, G. N., Jr., Alvarez, R. , Cali, J.

P. (NBS retired), Eberhardt, K. R., Reeder, D. J., Schaffer, R., Uriano, G. A., Elser, R., Ewen, L. M. , McComb, R. B., Rej, R., Shaw, L. M. , Standard Reference

Materials: The Measurement of the Catalytic

(Activity) Concentration of Seven Enzymes

in NBS Human Serum SRM 909. NBS Spec. 260-83 (June 1983) $4.50 SN003-003-024-99-6

Gills, T. E., Seward, R. W. , Collins,

R. J., and Webster, W. C, Standard Reference Materials Handling, Processing, and Packaging of NBS Sulfur in Coal Standard Reference

Materials, 2682, 2683, 2684, and 2685. NBS Spec. Publ. 260-84 (August

1983) $4.50 SN003-003-025-20-8

viii
TABLE OF CONTENTS

PAGE

Abstract 1 Introduction 2 General Description of SRM 3 Preparation of the Compacts 3 Characterization of SRM 488 5 Summary 12 Acknowledgements 12 References 13

LIST OF TABLES

1. Chemical Analysis of Stainless Steel Powder 5

LIST OF FIGURES

1. Scanning electron micrographs of the powders used

to produce SRM 488 4

2. Fabrication procedure for SRM 488 6

3. General microstructure of a compact 7 4. Characterization steps for SRM 488 10

5. Calibration curve showing the volume percent

austenite as a function of weight percent nickel . . 11

ix

A Standard Reference Material Containing

Two And One-Half Percent Austenite (SRM 488)

G. E. Hicho and E. E. Eaton

Fracture and Deformation Division Center for Materials Science

National Measurement Laboratory

National Bureau of Standards Washington, D.C. 20234

Abstract

This Standard Reference Material, SRM 488, is intended for the calibration of x-ray diffraction equipment used in determining the amount of retained austenite in hardened steels. The SRM was produced using powder metallurgical techniques and involved blending

2 1/2 percent by weight AISI type 310 stainless steel powder

(austenitic) with AISI type 430 stainless steel powder (ferritic). From this blend, 389 compacts were produced and subsequently

examined for nickel content by x-ray fluorescence spectrometry. A calibration curve was established using 13 compacts randomly selected from the population of 389. The curve relates the weight

percent nickel obtained from x-ray fluorescence measurements to the volume percentage austenite as determined by quantitative microscopy

measurements of the area percent. The curve was then used to assign

the certified values to the remaining compacts. This SRM may be used

as an x-ray diffraction standard for retained austenite or in very

special cases as an x-ray fluorescence standard for nickel content.

Key Words: austenite in ferrite; powder metallurgy; quantitative

microscopy; retained austenite standard; Standard Reference

Material; x-ray fluorescence.

(1) Student, Mechanical Engineering Department, University of Maryland.

1
Introduction

This Standard Reference Material was produced in order to calibrate x-ray diffraction (XRD) equipment used to determine the amount of retained austenite in hardened steels. The National Bureau of Standards is in the process of producing

a series of SRM's containing various percentages of austenite in ferrite. The first of these was issued in 1970 and contained

nominally four percent austenite [1]. A second issue of that SRM is available and in addition, 15% and 30% austenite in ferrite SRM's

are also available.

In various heat treating processes, steel is heated to a temperature where a face-centered-cubic solid phase called austenite

is formed. After a sufficient stabilization time, the steel is quenched into a medium where the austenite may be entirely transformed to a metastable, body-centered-tetragonal solid phase called martensite. However, sometimes the austenite is not completely transformed to martensite. The untransformed (retained)

austenite could be detrimental to the properties of the finished

product. Often there are requirements as to the maximum amount of retained austenite permitted in hardened steels. Therefore, it is necessary to quantitatively determine the amount of the retained

austenite in the finished product. The amount of retained austenite in steel is usually determined

by XRD procedures using a direct comparison of the integrated

intensities of a series of both austenite and ferrite diffraction

lines. It is highly recommended that the user of SRM 488 read National Bureau of Standards (NBS) Technical Note 709 [2],

describing the x-ray method used at the National Bureau of Standards

(NBS) to determine the amount of austenite in an austeni te-ferrite

mixture, prior to using this SRM. An XRD reference material for retained austenite should be reasonably free of certain metallurgical problems which severely

affect the intensities of both the austenite and ferrite lines - preferred granular orientation, large grain size, and residual

stress. The previously issued NBS austenite standard (SRM 486 [3]) was found to be reasonably free of these problems. The present SRM

(488) should also be free of these problems since it was prepared in

a similar manner, and should be very useful in determining the amount of retained austenite in hardened steels.

A separate characterization of the austenite content for each compact is required because a homogenous blend of austenite in ferrite cannot be guaranteed to the degree required. Therefore,

each compact is individually certified.

The purpose of this paper is to present a detailed description

of the preparation and characterization of the 389 compacts, and their subsequent certification as SRM 488.

2
General Description of the SRM

This SRM is composed of two constituents whose structures are

metal lurgical ly different. The components are AISI type 310 stainless steel (austenitic) and AISI type 430 stainless steel (ferritic) powders. The 310 is a highly stable austenitic stainless

steel (24.99 weight percent Cr and 20.41 weight percent Ni)

requiring a substantial change in composition to produce a transformation to a structure other than austenite. The 430 contains 16.82 weight percent Cr, and effectively no nickel - .08 weight percent.

Following the blending of the powders, the powders were pressed

into compacts and subsequently sintered, repressed, and vacuum

annealed. The finished compacts were approximately 21 mm (.83 in)

in diameter and 2.4 mm (.094 in) thick. Only one surface of the SRM

was polished, and it is that surface which is certified as to the austenite content. No surface preparation of the SRM is necessary - in fact damage to the surface renders the certification

void. The main concept of the SRM is that the austenite content for each compact is related directly to the nickel content. Because of the significant differences between the nickel content of the austenitic component (20.41 weight percent) and that of the ferritic

component (.08 weight percent), it was possible to use x-ray fluorescence analysis to obtain a precise measurement of total nickel counts on the surface of the compact. The total nickel counts were then corrected to weight percent nickel. Using a calibration curve (described later) and the values obtained by XRF analyses, it was possible to assign a volume percent

austenite to each compact.

Preparation of the Compacts

The austenitic and ferritic powders used to make this SRM were

produced by water atomization techniques. The preliminary sizing of

the powders was done by the manufacturer. Final sizing however, was done at the National Bureau of Standards.

The austenitic stainless steel powder passed a 250 mesh screen, but was retained on a 325 mesh screen. This sieving yielded 310 stainless steel powder in the particle size range of 53 to 44 micrometers. The ferritic stainless steel powder passed a 325 mesh

screen, but was retained on a 400 mesh screen. This yielded 430 stainless steel particles in the size range of 44 to 37 micrometers.

Micrographs of the powders are shown in figure 1. Each powder was

then sampled and chemically analyzed. The results of the chemical analyses are shown in Table 1.

3
4
Table I. Chemical Analysis of Stainless Steel Powder. (Content in Weight Percent)

Elements 310 Stainless

Steel 430 Stainless

Steel Chromium 24.99

20.41 0.05 0.20

0.01 0.007

0.75

bal

16.82 0.08

0.02 0.15 0.005 0.008

0.83

bal

Nickel Carbon Manganese

Phosphorus Sulfur

Si 1 icon

Iron The steps followed in the preparation of SRM 488 are shown in figure 2. After three cycles of pressing and heat treatment (843°C, 30 minutes) in a vacuum, each compact was hand ground on silicon carbide papers, and then polished on felt cloths using 6y and ly

diamond paste. Mineral spirits was used as a lubriciant during

polishing. The temperature of 843°C was chosen as the sintering and annealing temperature since it was found [3] that at this temperature diffusion of the nickel into the ferrite was minimal. Micrographs of a compact, at low and high magnifications, are shown

in figure 3. As the final step in the procedure, each compact was polished

on microcloth using 3-alumina as the abrasive and distilled water as the lubricant. Upon completion of this step, the weight percent

nickel of each compact's surface was determined using x-ray fluorescence spectrometry.

Certain basic XRF concepts were used in the determination of

the weight percent nickel in SRM 488. These concepts will now be discussed. Although an alloy steel, each compact may be considered to consist of high purity Fe, Ni , and Cr powders. In the XRF analysis,

these elements were treated as unknowns. Because of this, it was possible to analyze for all three elements in each compact using the combined procedure of Rasberry-Heinrich [4] and the Naval Research Laboratory [5] programs for the correction of interelement effects.

An AXS, automated wavelength x-ray spectrometer, employing a Cr target with an Al filter, operating at either 50KV, 10MA, or 50KV, 15MA was used. To reduce the effect of surface inhomogenei ty of the austenite, each compact was rotated at about 10 RPM with its axis tilted approximately 60° to the beam, and examined for approximately

30 seconds.

Characterization of SRM 488

5
6
Figure 3. General microstructure of a compact.

a. Optical microgrpah showing the white

austenite particles in the ferrite

mixture. Mag. X50.

b. Optical micrograph of an enlarged

austenite particle. Mag. X800.

7
For check purposes during XRF examination, three specimens,

each containing a different weight percent nickel, were prepared.

Specimen A, containing 1.439 weight percent nickel, was prepared in the same manner as described previously; i.e., press, sinter, press,

etc. An extensive number of measurements using a quantitative

microscope (QM) were performed on this compact and its area percent

austenite value was known with high accuracy. Specimens B and F (corresponding to the 5 and 2 1/2 area percent austenite compacts) were made using pure chromium, nickel, and iron powders. But, unlike A, they were vacuum melted into buttons and subsequently

machined to fit a holder. Filings from these compacts were individually examined for nickel content using atomic absorption

spectrometry. The mean for six determinations of weight percent

nickel in B was 1.511 with a standard deviation of 0.009. Likewise,

the mean for two determinations of nickel in F, was 0.8163. Specimens A, B, and F were then used as calibration checks on the x-ray spectrometer during the analysis of each compact.

A summary of the XRF precision data on samples A, B, and F is as follows. The mean weight percent nickel for 13 XRF determinations of specimen A was 1.437 with a standard deviation of

.011 and relative standard deviation of 0.8%. The mean weight

percent nickel for 13 XRF determinations of specimen B was 1.509 with a standard deviation of 0.010 and a relative standard deviation

of 0.70%. The mean for 4 determinations of specimen F was 0.809 with a standard deviation of 0.019. Following the XRF determination of the weight percent nickel for each compact, the total population was ranked from lowest to highest weight percent nickel in order to select compacts to be used

in the establishment of the calibration curve. It should be noted that the nickel content ranged from 0.605 to .825 weight percent

nickel. This was benefical in that a limited number of calibration

samples would then be required to establish the calibration curve. The calibration curve is a plot of the volume percent

austenite, which is equivalent to the area percent [6] austenite

value as determined from QM procedures, along the ordinate and the weight percent nickel value as determined by XRF along the abscissa.

It is this calibration curve which permits the assignment of a volume percent austenite from a corresponding weight percent nickel

(XRF).As stated, the QM method is used to determine the area percent

austenite on the calibration compact's surface. However prior to this determination, it was necessary to ascertain the area percent

porosity of the compact's surface since this value is needed to correct the area percent austenite determined later.

A polished compact is inserted into a holder and placed on the microscope's stage. Mathematically the compact's surface, and part

8
of the holder is divided into cells, each 0.625 mm square. There

are 34 cells in a row and 34 rows. During the scanning of the compact, the area percent porosity is obtained for each cell and recorded so that it can be used later. Once the 1156 cells have been scanned, an equation is used to extract data equivalent to an area 90% of the compact's surface. The data are then statistically

analysed, and the appropriate mean porosity, standard deviation,

etc. obtained. Following the porosity determination, the area percent austenite was determined.

In order to determine the area percent of austenite on the compact's surface using QM methods, the austenite (the 310 stainless

steel component) had to "stand out" from the ferrite background. An extensive amount of research was conducted in order to find a stain

that permitted this. Murakami's reagent, (10 grams potassium

hydroxide (KOH), 10 grams potassium ferricyanide (K~ Fe (CN)

fi ), and

100 mL distilled water), when heated to about 100°C, stainedb the compact so that the austenite (310) was unattacked and the ferrite

was stained dark red. Hence it was now possible to use the QM to determine the percentage of white particles (i.e. austenite) on the component's surface. Following the same QM procedure described previously for the porosity determination, each of the 13 calibration compacts were

stained with Murakami ' s reagent and the area percent austenite and standard deviation determined.

In order to ascertain the extent of inhomogeneity of the austenite over the compact's surface, a normalization of the data using the standard deviation was performed.

The relationship used in the normalization procedure was (A-B)/S, where A is the area percent austenite value for that cell,

and B and S are the mean and standard deviation obtained for the compact's surface. The value obtained for each cell was subsequently plotted and a pattern was obtained which revealed the extent of inhomogeneity that existed on the compact's surface. If the normalization revealed a surface with excessive austenite

inhomgeneity , the compact was discarded. None of the calibration

compacts showed any severe inhomogeneity to the extent that it would

be discarded. The characterization steps used for this SRM are shown in figure 4. The calibration curve was fitted using least-square regression

methods. The calibration data are plotted in figure 5. The equation for the curve using the 13 calibration points is as

fol lows: Volume percent austenite = 4.066X - 0.546 where X represents the weight percent nickel as determined by XRF spectrometry.

9
X-RAY FLUORESCENCE

ANALYSIS

SELECT 13 CALIBRATION SPECIMENS

389 COMPACTS

RANKED BY WGT % NICKEL MEASURE POROSITY

BY QM METHODS

STAIN: MURAKAMIS

REAGENT

DETERMINE AREA PERCENT AUSTENITE

BY QM METHODS

CORRECT AREA

% FOR POROSITY

ESTABLISH

CALIBRATION CURVE

ASSIGN PERCENT

AUSTENITE TO

376 COMPACTS

370 COMPACTS

AS CERTIFIED STANDARD

REFERENCE

MATERIALS

6 COMPACTS

RETAINED FOR

USE IN RESEARCH

AT NBS

Figure 4. Characterization steps for SRM 488.

10
11
The equation to be used for the standard deviation (SD), i.e. uncertainty of a single compact based on errors of the calibration

curve is as follows:

SD = (.177) [1/13 + 19.799 ( X- . 7067

)

2

] 1/2

[7] where X represents the weight percent nickel as determined by XRF spectrometry. Using this equation, the calibration curve uncertainty does not exceed ±0.10 volume percent austenite.

However, a larger uncertainty is assigned to each certified compact,

namely ±0.30 volume percent austenite. This uncertainty encompasses

the uncertainty associated with the calibration curve, involving

both the QM and XRF measurements, and the potential bias in the measured values. Sources of known bias are primarily the porosity

correction applied to each specimen, and the QM threshold setting

used for each of the calibration specimens.

Summary

SRM 488 is satisfactory for issuance as a standard for x-ray determination of retained austenite in hardened steels. The range for the 389 certified compacts is within the range of 1.91 to 2.96 volume percent austenite. The mean content for these compacts is 2.23 volume percent austenite. The initial blend was prepared so that it contained 2.5 weight percent austenite and this corresponds

to a volume percent of 2.41. Thorough statistical analysis of the data associated with the QM and XRF measurements could not reconcile

this difference between these two values. Consideration of the sources of potential bias in all the measurements also could not account for this difference. The most likely explanation presumes

that the austenite distribution throughout the volume of each compact is not uniform. Recall that some compacts were rejected because the surface distribution of austenite was not sufficiently

uniform, but no studies were conducted on the volume distribution.

Since only the prepared, certified surface of the SRM is to be used,

this effect if present should have no consequence in a proper measurement program.

In using SRM 488 in an x-ray measurement series, it is highly recommended that the compact be rotated in order to minimize the effect of possible inhomogenei ty of the certified surface. In addition, the user should read NBS Technical Note 709 prior to using

the SRM. Acknowledgements

The authors thank P. Pel la of the X-Ray Fluorescence Group for

his effort in determining the nickel content of the compacts. In addition, we thank F. Biancaniello who prepared the XRF check

samples and heat treated all of the compacts.

12
Special thanks are due also to the statisticians, J. Filliben,

H. Ku, and S. Leigh, who aided us in the analysis of the data generated during the preparation of this SRM. And finally, thanks

are due to our secretaries, P. Salpino and D. Easterday, both of whom worked so diligently on this manuscript.

References

[1] Hicho, G. E. et al . , A Standard Reference Material Containing

Nominally Four Percent Austenite. Natl. Bur. Stand. (U.S.)

Spec. Publ. 260-25; 1971 February. 14p.

[2] Bechtold, C. J. An X-Ray Diffraction Method for Determining

the amount of Austenite in an Austeni te-Ferri te Mixture.

Natl. Bur. Stand. (U.S.) Tech. Note 709; 1972 February. 14p.

[3] Interrante, C. G. and Hicho, G. E., A Standard Reference

Material Containing Nominally Fifteen Percent Austenite.

Natl. Bur. Stand. (U.S.) Spec. Publ. 260-73; 1982 January. 25p.

[4] Rasberry, S. D., and Heinrich, K. F. J., Calibration of Interelement Effects in X-Ray Fluorescence Analysis, Analytical

Chemistry, Vol. 46, Page 81, 1974 January.

[5] Birks, L. S., Gilfrich, J. V., and Criss, J. W. , NRLXRF, A Fortran Program for X-Ray Fluorescence Analysis, X-Ray Optics

Branch, Materials Science Division, NRL, Washington, D.C. 1977 (COSMIC) Suite 112, Barrow Harrow, Athens, GA. 30602. Project Number D0D-00065 (July 1977 revision).

[6] Delesse, A., "Pourdeterminer la composition des roches,"

Ann. des Mines B (1848), fourth series, pp. 378-388.

[7] Walpole, R.E., Myers, R.H., Probability and Statistics for Engineers and Scientists, 2nd editions, pp. 289-295.

13
NBS-114A (REV. 2-8C) U.S. DEPT. OF COMM. 1. PUBLICATION OR 2. Performing Organ. Report No. 3. Publication Date BIBLIOGRAPHIC DATA REPORT NO. December 1983

SHEET (See instructions) NBS SP 260-86

4. TITLE AND SUBTITLE Standard Reference Materials:

A Standard Reference Material Containing Two And One-Half Percent Austenite (SRM 488)

5. AUTHOR(S)

G. E. Hicho, E. E. Eaton

6. PERFORMING ORGANIZATION (If joint or other than NBS. see instructions) NATIONAL BUREAU OF STANDARDS DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

7. Contract/Grant No.

8. Type of Report & Period Covered Final

9. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street. City, State, ZIP)

Same as item 6.

10. SUPPLEMENTARY NOTES Library of Congress Catalog Card Number: 83-600613 J Document describes a computer program; SF-185, FIPS Software Summary, is attached.

11. ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant bibliography or literature survey, mention it here) This Standard Reference Material, SRM 488, is intended for the calibration of x-ray diffraction equipment used in determining the amount of retained austenite

in hardened steels. The SRM was produced using powder metallurgical techniques and involved blending 2 1/2 percent by weight AISI type 310 stainless steel powder

(austenitic) with AISI type 430 stainless steel powder (ferritic). From this blend, 389 compacts were produced and subsequently examined for nickel content by x-ray fluorescence spectrometry. A calibration curve was established using 13 compacts

randomly selected from the population of 389. The curve relates the weight percent

nickel obtained from x-ray fluorescence measurements to the volume percentage

austenite as determined by quantitative microscopy measurements of the area

percent. The curve was then used to assign the certified values to the remaining

compacts. This SRM may be used as an x-ray diffraction standard for retained

austenite or in very special cases as an x-ray fluorescence standard for nickel content.

12. KEY WORDS (Six to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolons) austenite in ferrite; powder metallurgy; quantitative microscopy; retained austenite

standard; Standard Reference Material; x-ray fluorescence.

13. AVAILABILITY

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