ASTM E975-03(2008)
(Practice)Standard Practice for X-Ray Determination of Retained Austenite in Steel with Near Random Crystallographic Orientation
Standard Practice for X-Ray Determination of Retained Austenite in Steel with Near Random Crystallographic Orientation
SIGNIFICANCE AND USE
Significance—Retained austenite with a near random crystallographic orientation is found in the microstructure of heat-treated low-alloy, high-strength steels that have medium (0.40 weight %) or higher carbon contents. Although the presence of retained austenite may not be evident in the microstructure, and may not affect the bulk mechanical properties such as hardness of the steel, the transformation of retained austenite to martensite during service can affect the performance of the steel.
Use—The measurement of retained austenite can be included in low-alloy steel development programs to determine its effect on mechanical properties. Retained austenite can be measured on a companion sample or test section that is included in a heat-treated lot of steel as part of a quality control practice. The measurement of retained austenite in steels from service can be included in studies of material performance.
SCOPE
1.1 This practice covers the determination of retained austenite phase in steel using integrated intensities (area under peak above background) of X-ray diffraction peaks using chromium Kα or molybdenum Kα X-radiation.
1.2 The method applies to carbon and alloy steels with near random crystallographic orientations of both ferrite and austenite phases.
1.3 This practice is valid for retained austenite contents from 1 % by volume and above.
1.4 If possible, X-ray diffraction peak interference from other crystalline phases such as carbides should be eliminated from the ferrite and austenite peak intensities.
1.5 Substantial alloy contents in steel cause some change in peak intensities which have not been considered in this method. Application of this method to steels with total alloy contents exceeding 15 weight % should be done with care. If necessary, the users can calculate the theoretical correction factors to account for changes in volume of the unit cells for austenite and ferrite resulting from variations in chemical composition.
1.6 Units—The values stated in inch-pound units are to be regarded as standard. No other units of measurement are included in this standard.
1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: E975 − 03(Reapproved 2008)
Standard Practice for
X-Ray Determination of Retained Austenite in Steel with
1
Near Random Crystallographic Orientation
This standard is issued under the fixed designation E975; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
The volume percent of retained austenite (face-centered cubic phase) in steel is determined by
comparing the integrated chromium or molybdenum X-ray diffraction intensity of ferrite (bodycen-
tered cubic phase) and austenite phases with theoretical intensities. This method should be applied to
steels with near random crystallographic orientations of ferrite and austenite phases because preferred
crystallographicorientationscandrasticallychangethesemeasuredintensitiesfromtheoreticalvalues.
Chromium radiation was chosen to obtain the best resolution of X-ray diffraction peaks for other
crystalline phases in steel such as carbides. No distinction has been made between ferrite and
martensite phases because the theoretical X-ray diffraction intensities are nearly the same. Hereafter,
the term ferrite can also apply to martensite. This practice has been designed for unmodified
commercial X-ray diffractometers or diffraction lines on film read with a densitometer.
Other types of X-radiations such as cobalt or copper can be used, but most laboratories examining
ferrous materials use chromium radiation for improved X-ray diffraction peak resolution or
molybdenum radiation to produce numerous X-ray diffraction peaks. Because of special problems
associated with the use of cobalt or copper radiation, these radiations are not considered in this
practice.
1. Scope necessary, the users can calculate the theoretical correction
factors to account for changes in volume of the unit cells for
1.1 This practice covers the determination of retained aus-
austenite and ferrite resulting from variations in chemical
tenite phase in steel using integrated intensities (area under
composition.
peak above background) of X-ray diffraction peaks using
chromium K or molybdenum K X-radiation.
α α
1.6 Units—The values stated in inch-pound units are to be
1.2 The method applies to carbon and alloy steels with near regarded as standard. No other units of measurement are
included in this standard.
random crystallographic orientations of both ferrite and aus-
tenite phases.
1.7 This standard does not purport to address all of the
1.3 This practice is valid for retained austenite contents
safety concerns, if any, associated with its use. It is the
from 1 % by volume and above.
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
1.4 If possible, X-ray diffraction peak interference from
bility of regulatory limitations prior to use.
other crystalline phases such as carbides should be eliminated
from the ferrite and austenite peak intensities.
2. Significance and Use
1.5 Substantial alloy contents in steel cause some change in
peak intensities which have not been considered in this
2.1 Significance—Retained austenite with a near random
method. Application of this method to steels with total alloy
crystallographic orientation is found in the microstructure of
contents exceeding 15 weight % should be done with care. If
heat-treated low-alloy, high-strength steels that have medium
(0.40 weight %) or higher carbon contents. Although the
1 presence of retained austenite may not be evident in the
This practice is under the jurisdiction of ASTM Committee E04 on Metallog-
raphy and is the direct responsibility of Subcommittee E04.11 on X-Ray and
microstructure, and may not affect the bulk mechanical prop-
Electron Metallography.
erties such as hardness of the steel, the transformation of
Current edition approved June 1, 2008. Published September 2008. Originally
retained austenite to martensite during service can affect the
approved in 1984. Last previous edition approved in 2003 as E975 – 03. DOI:
10.1520/E0975-03R08. performance of the steel.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
E975 − 03 (2008)
A
TABLE 1 Calculated Theoretical Intensities Using Chromium K Radiation
α
2 B 2
hkl Sinθ/λθ f ∆f8 ∆f9 /F/ LP P T N R
(α iron, body-centered cubic, unit-cell dimension a = 2.8664Å):
o
B C
110 0.24669 34.41 18.474 −1.6 0.9 1142.2 4.290 12 0.9577 0.001803 101.5
B C
200 0.34887 53.06 15.218 −1.6 0.9 745.0 2.805 6 0.9172 0.001803 20.73
B C
211 0.42728 78.20 13.133 −1.6 0.8 534.6 9
...
This document is not anASTM standard and is intended only to provide the user of anASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation:E975–00 Designation:E975–03 (Reapproved 2008)
Standard Practice for
X-Ray Determination of Retained Austenite in Steel with
1
Near Random Crystallographic Orientation
This standard is issued under the fixed designation E975; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
The volume percent of retained austenite (face-centered cubic phase) in steel is determined by
comparing the integrated chromium or molybdenum X-ray diffraction intensity of ferrite (bodycen-
tered cubic phase) and austenite phases with theoretical intensities. This method should be applied to
steelswithnearrandomcrystallographicorientationsofferriteandaustenitephasesbecausepreferred
crystallographicorientationscandrasticallychangethesemeasuredintensitiesfromtheoreticalvalues.
Chromium radiation was chosen to obtain the best resolution of X-ray diffraction peaks for other
crystalline phases in steel such as carbides. No distinction has been made between ferrite and
martensite phases because the theoretical X-ray diffraction intensities are nearly the same. Hereafter,
the term ferrite can also apply to martensite. This practice has been designed for unmodified
commercial X-ray diffractometers or diffraction lines on film read with a densitometer.
Other types of X-radiations such as cobalt or copper can be used, but most laboratories examining
ferrous materials use chromium radiation for improved X-ray diffraction peak resolution or
molybdenum radiation to produce numerous X-ray diffraction peaks. Because of special problems
associated with the use of cobalt or copper radiation, these radiations are not considered in this
practice.
1. Scope
1.1 Thispracticecoversthedeterminationofretainedaustenitephaseinsteelusingintegratedintensities(areaunderpeakabove
background) of X-ray diffraction peaks using chromium K or molybdenum K X-radiation.
a a
1.2 The method applies to carbon and alloy steels with near random crystallographic orientations of both ferrite and austenite
phases.
1.3 This practice is valid for retained austenite contents from 1% by volume and above.
1.4 Ifpossible,X-raydiffractionpeakinterferencefromothercrystallinephasessuchascarbidesshouldbeeliminatedfromthe
ferrite and austenite peak intensities.
1.5 Substantial alloy contents in steel cause some change in peak intensities which have not been considered in this method.
Application of this method to steels with total alloy contents exceeding 15 weight% should be done with care. If necessary, the
users can calculate the theoretical correction factors to account for changes in volume of the unit cells for austenite and ferrite
resulting from variations in chemical composition.
1.6 Units—The values stated in inch-pound units are to be regarded as standard. No other units of measurement are included
in this standard.
1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
2. Significance and Use
2.1 Significance—Retained austenite with a near random crystallographic orientation is found in the microstructure of
heat-treated low-alloy, high-strength steels that have medium (0.40 weight%) or higher carbon contents. Although the presence
of retained austenite may not be evident in the microstructure, and may not affect the bulk mechanical properties such as hardness
1
This practice is under the jurisdiction of ASTM Committee E04 on Metallography and is the direct responsibility of Subcommittee E04.11 on X-Ray and Electron
Metallography.
Current edition approved July 10, 2000. Published October 2000. Originally published as E975–84. Last previous edition E975–95.
Current edition approved June 1, 2008. Published September 2008. Originally approved in 1984. Last previous edition approved in 2003 as E975–03.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
1
---------------------- Page: 1 ----------------------
E975–03 (2008)
A
TABLE 1 Calculated Theoretical Intensities Using Chromium K Radiation
a
2 B 2
hkl Sinu/lu f Df8 Df9 /F/ LP P T N R
(a iron, body-centered cubic, unit-cell dimension a = 2.
...
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