This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles

for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

Designation: E975 − 22

Standard Test Method for

X-Ray Determination of Retained Austenite in Steel with
Near Random Crystallographic Orientation1
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 (body-
centered 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 crystallographic orientations can drastically change these measured intensities from
theoretical values. 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 test method 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 test
method.

1. Scope necessary, the users can calculate the theoretical correction

1.1 This test method covers the determination of retained factors to account for changes in volume of the unit cells for
austenite phase in steel using integrated intensities (area under austenite and ferrite resulting from variations in chemical
peak above background) of X-ray diffraction peaks using composition.
chromium Kα or molybdenum Kα X-radiation. 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. The values given in parentheses are
random crystallographic orientations of both ferrite and aus- mathematical conversions to SI units that are provided for
tenite phases. information only and are not considered standard.
1.3 This test method is valid for retained austenite contents 1.7 This standard does not purport to address all of the
from 1 % by volume and above. safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
1.4 If possible, X-ray diffraction peak interference from priate safety, health, and environmental practices and deter-
other crystalline phases such as carbides should be eliminated mine the applicability of regulatory limitations prior to use.
from the ferrite and austenite peak intensities. 1.8 This international standard was developed in accor-
1.5 Substantial alloy contents in steel cause some change in dance with internationally recognized principles on standard-
peak intensities which have not been considered in this ization established in the Decision on Principles for the
method. Application of this method to steels with total alloy Development of International Standards, Guides and Recom-
contents exceeding 15 weight % should be done with care. If mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
1
This test method is under the jurisdiction of ASTM Committee E04 on
Metallography and is the direct responsibility of Subcommittee E04.11 on X-Ray 2. Significance and Use
and Electron Metallography.
2.1 Significance—Retained austenite with a near random
Current edition approved Nov. 1, 2022. Published February 2023. Originally
approved in 1984. Last previous edition approved in 2013 as E975 –13, which was crystallographic orientation is found in the microstructure of
withdrawn in July 2022 and reinstated in November 2022. DOI: 10.1520/E0975-22. heat-treated low-alloy, high-strength steels that have medium

Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States

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 E975 − 22
(0.40 weight %) or higher carbon contents. Although the p = multiplicity factor of the (hkl) reflection,
presence of retained austenite may not be evident in the θ = Bragg angle,
microstructure, and may not affect the bulk mechanical prop- LP = Lorentz Polarization factor for a Bragg-Brentano
erties such as hardness of the steel, the transformation of powder diffractometer is equal to (1 + cos2 2θ)/sin2
retained austenite to martensite during service can affect the θ cos θ for normal diffractometric analysis but
performance of the steel. becomes2 (1 + cos22α cos2 2θ)/(sin2 θ cos θ)
2.2 Use—The measurement of retained austenite can be (1 + cos 2α) when a monochromator is used in
included in low-alloy steel development programs to determine which diffraction by monochromator and specimen
its effect on mechanical properties. Retained austenite can be take place in the same plane; 2α is the diffraction
measured on a companion specimen or test section that is angle of the monochromator crystal. If diffraction
included in a heat-treated lot of steel as part of a quality control by the monochromator occurs in a plane perpen-
practice. The measurement of retained austenite in steels from dicular to the plane of specimen diffraction, then
service can be included in studies of material performance. LP = (cos22α + cos22θ)/(sin2θ cosθ) (1 + cos22α),
−2 M
e = Debye-Waller or temperature factor which is a
3. Principles for Retained Austenite Measurement by function of θ where M = B( sin2 θ)/λ2, B = 8π 2 (µs)2,
X-Ray Diffraction where µs 2 is the mean square displacement of the
atoms from their mean position, in a direction
3.1 A detailed description of a retained austenite measure- perpendicular to the diffracting plane, and
ment using X-ray diffraction is presented by the Society of Vα = volume fraction of the α-phase.
Automotive Engineers.2 Since steel contains crystalline phases
such as ferrite or martensite and austenite, a unique X-ray K is a constant which is dependent upon the selection of
diffraction pattern for each crystalline phase is produced when instrumentation geometry and radiation but independent of the
the steel sample is irradiated with X-irradiation. Carbide nature of the specimen. The parameter, R, is proportional to the
phases in the steel will also produce X-ray diffraction patterns. theoretical integrated intensity. The parameter, R, depends
upon interplanar spacing (hkl), the Bragg angle, θ, crystal
3.2 For a randomly oriented specimen, quantitative mea- structure, and composition of the phase being measured. R can
surements of the relative volume fraction of ferrite and be calculated from basic principles.
austenite can be made from X-ray diffraction patterns because
the total integrated intensity of all diffraction peaks for each 3.3 For steel containing only ferrite (α) and austenite (γ) and
phase is proportional to the volume fraction of that phase. If the no carbides, the integrated intensity from the (hkl) planes of the
crystalline phase or grains of each phase are randomly ferrite phase is expressed as:
oriented, the integrated intensity from any single diffraction I α hkl 5 KRα hkl V α /2µ
peak (hkl) crystalline plane is also proportional to the volume 3.3.1 A similar equation applies to austenite. We can then
fraction of that phase: write for any pair of austenite and ferrite hkl peaks:
hkl
Iα 5 KRα hkl V α /2µ I α hkl /I γ hkl
5 @ ~ R α hkl /R γ hkl!~ V α /V γ ! #
where: 3.3.2 The above ratio holds if ferrite or martensite and
austenite are the only two phases present in a steel and both
K5
I oe 4
m c2 4S DS D
×
λ 3A
32πr phases are randomly oriented. Then:
and V α 1V γ 5 1

hkl
1 ~ /F/ pLPe
2 22M
! 3.3.3 The volume fraction of austenite (Vγ) for the ratio of
Rα 5 measured integrated intensities of ferrite and austenite peak to
v2
R-value is:
where:
V γ 5 ~ I γ / R γ !/ @ ~ I α /R α ! 1 ~ I γ /R γ ! # (1)
Iα hkl = integrated intensity per angular diffraction peak
(hkl) in the α-phase, 3.3.4 For numerous ferrite and austenite peaks each ratio of
Io = intensity of the incident beam, measured integrated intensity to R-value can be summed:
µ = linear absorption coefficient for the steel,
e,m
r
= charge and mass of the electron,
= radius of the diffractometer,
Vγ 5 S 1
q
q

(I
j51
γj D FS
⁄R γj /
1
P
P

(I
i51
αi /R αi D S
1
1
q (I
j51
q

γj /R γj DG (2)

c = velocity of light, where:

λ = wavelength of incident radiation,
A = cross sectional area of the incident beam, q = total number of austenite peaks, and
v = volume of the unit cell, P = total number of ferrite peaks.
/F/2 = structure factor times its complex conjugate, 3.3.5 If carbides are present:
V α 1V γ 1V c 51

2
Retained Austenite and Its Measurement by X-ray Diffraction , SAE Special
3.3.6 Then the volume fraction of austenite (Vα) for the ratio
Publication 453, Society of Automotive Engineers (SAE), 400 Commonwealth Dr., of measured ferrite and austenite integrated intensity to R-value
Warrendale, PA 15096-0001, http://www.sae.org. is:

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 E975 − 22
Vγ 5 ~1 2 V c ! ~ I γ /R γ ! / @ ~ I α /R α ! 1 ~ I γ /R γ ! # (3) 4.1.5.1 When using molybdenum radiation, select peaks in
the range from 28° to 40° 2θ for best results.
3.3.7 For numerous ferrite and austenite peaks the ratio of
measured integrated intensity to R-values can be summed: 4.2 X-Ray Equipment:
4.2.1 Any diffraction system may be used that consists of an
V γ 5 ~ 1 2 V c! (4)
x-ray source, an angular measurement capability, and an x-ray
detection system. The system shall be capable of obtaining the
FS 1
q ( ~ Iγj/Rγj ! D G / F P ( ~ I
q

j51
1 p

i51
a i/R a i ! 1
1
q
q

( ~I
j51
r i/R r i ! G entire diffraction peak along with adjacent background levels,
capable of detecting at least two separate austenite reflections
3.4 The volume fraction of carbide, Vc, should be deter- and a ferrite reflection, and capable of normalizing any
mined by chemical extraction or metallographic methods. equipment-specific intensity biases not accounted for by
Adequate X-ray diffraction peak resolution for the identifica- R-factors. Two separate ferrite reflections should be measured;
tion of carbide peaks is required to avoid including carbide however, in alloys with known carbide interference, only the
peaks in the retained austenite measurement. unaffected ferrite reflection may be measured.
4.2.2 A chromium X-ray source with a vanadium metal or
4. Procedure compound filter to reduce the Kβ radiation is should be used.
4.1 Specimen Preparation: NOTE 4—Chromium radiation produces a minimum of X-ray fluores-
4.1.1 Specimens for the X-ray diffractometer shall be cut cence of iron. Chromium radiation provides for the needed X-ray
with a minimum amount of heat effect. Saw cutting rather than diffraction peak resolution and allows for the separation of carbide peaks
abrasive wheel cutting should be for specimen removal when- from austenite and ferrite peaks.
ever it is practical. 4.2.3 Other radiation such as copper, cobalt, or molybde-
num may be used, but none of these provide the resolution of
NOTE 1—Since most steels containing retained austenite are relatively
hard, abrasive cutoff wheels are frequently used. If adequate cooling is not
chromium radiation.
used, heat effects from abrasive cutoff wheels can be substantial and, in NOTE 5—Copper radiation is practical only when a diffracted-beam
some cases, can transform retained austenite. monochromator is employed, because iron X-ray fluorescence will ob-
NOTE 2—Rough machining using a milling tool or coarse grinding can scure the diffracted peaks.
deform the surface and transform some of the retained austenite to a depth
that is greater than the surface depth analyzed. Final milling or rough 4.2.4 A molybdenum source with a zirconium filter may be
grinding cuts limited to a depth of 0.010-in (0.254 mm) or less will reduce used to produce a large number of X-ray diffraction peaks.
the depth of deformation.
4.3 X-Ray Method—X-ray diffraction peaks from other
4.1.2 Standard metallographic wet-grinding and polishing crystalline phases such as carbides shall be separated from
methods shall be used to prepare specimens for X-ray analysis. austenite and ferrite peaks. The linearity of the chart recorder
Grit reductions of 80, 120, 240, 320, 400, and 600 silicon or photographic film shall be verified prior to utilizing this
carbide or alumina abrasives may be used, but other valid grit method for older systems using these recording media.
combinations may also be used. 4.3.1 Entire diffraction peaks minus background under the
4.1.2.1 The final surface polish shall be 2.36 × 10-4in. peaks shall be recorded to obtain integrated peak intensities.
(6-µm) diamond or an equivalent abrasive polish. Peaks without carbide or second phase interference may be
4.1.2.2 Specimen etching, observation for heat effects, and scanned, and the total peak plus background recorded. Obtain
repolishing should be conducted as a safeguard. background counts by counting on each side of the peak for
4.1.3 Since deformation caused by dull papers or over- one-half of the total peak counting time. Subtract the total
polishing can transform some of the retained austenite, elec- background from peak plus background to obtain the integrated
trolytic polishing or chemical polishing of initial specimens of intensity. Alternatively, software supplied with the diffracto-
each grade and condition should be used to verify proper meter may be used. In general, the diffractometer scanning rate
metallographic specimen preparation. Standard chromic-acetic should be 0.5°2θ/min or less to define the peaks for austenite
acid for electropolishing 0.005-in. (0.127 mm) from specimens contents of less than 5 %.
ground to 600 grit or specific chemical polishing solutions for 4.3.2 Where carbide or other phase X-ray diffraction peak
a particular grade of steel polished to a 2.36 × 10-4in. (6-µm) interference exists, planimeter measurements of area under the
finish may be used to verify the metallographic polish. Hot- austenite and ferrite peaks on X-ray diffraction charts may be
acid etching should not be used because of selective etching of used to obtain integrated intensity. Alternatively, software
one phase or along a preferred crystallographic direction. supplied with the diffractometer may be used.
4.1.4 If measurement of the retained austenite content on the NOTE 6—Details of the correction techniques are outside the scope of
surface of a specimen is desired and the specimen can be this test method. Carbide interference with austenite and ferrite peaks of
mounted in the diffraction system, no preparation is needed. the more common carbides is shown in Fig. 1.
4.1.5 Specimen size shall be large enough to contain the 4.3.3 The integrated intensity may be determined by cutting
X-ray beam at all angles of 2θ required for the X-ray peak areas from the charts and weighing them with an
diffraction analysis to prevent errors in the analysis. analytical balance.
NOTE 3—In most cases, an area of 1 in.2 (645.16 mm2) is sufficient, but 4.3.4 Assuming a 10 % variation in each peak intensity,
specimen size depends upon the dimensions of the incident X-ray chromium peak ratios of integrated intensities (areas under the
diffraction. peaks minus background) for the (220) austenite peak relative

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 E975 − 22

NOTE 1—“M” represents more than one type of metal.

FIG. 1 Example of Carbide Interference

to (200) austenite peak shall range from 1.1 to 1.7 to satisfy the peaks (110), (200), and (211) can be obtained with chromium radiation on
requirement of this test method for a near-random orientation most X-ray diffractometers. Chromium X-ray diffraction limitations may
prevent obtaining the entire peak profile for the (211) peak. In this case,
of austenite. Equivalent molybdenum peak ratios range from the half-peak profile can be doubled with some error in background. A
0.7 to 0.5. densitometer reading of film from a Debye Scherrer camera may also be
4.3.5 Assuming a 10 % variation in each peak intensity, used. In many cases, the (111) austenite and (110) ferrite peaks interfere
chromium peak ratios of integrated intensities for the (211) with each other and cannot be resolved. Four peak ratios of the resolved
ferrite peak relative to the (200) ferrite peak range from 8 to 11 ferrite to austenite peaks are adequate to determine the retained austenite
content of near randomly oriented specimens.
to satisfy the requirement of this test method for a near-random
orientation of ferrite. Equivalent molybdenum peak ratios 4.3.6 Calculated theoretical intensities, R, for ferrite and
range from 1.5 to 2.2. austenite peaks, for a Bragg-Brentano powder diffractometer,
are listed in Table 1 using chromium Kα radiation and in Table
NOTE 7—When either the austenite peak ratio or the ferrite peak ratio 2 using molybdenum Kα radiation. The R values shown are for
is above or below the specified range, this may indicate carbide interfer-
ence and/or preferred orientation which can result in an increase in only one type of steel. R values will vary with the composition
measurement error. of the steel and therefore should be calculated from first
NOTE 8—Three austenite peaks (111), (200), and (220) and three ferrite principles for each steel alloy tested to ensure accurate results.

TABLE 1 Calculated Theoretical Intensities Using Chromium Kα RadiationA

hkl Sinθ/λ θ f ∆f' ∆f9 /F/2 LP P TB N2 R
(α iron, body-centered cubic, unit-cell dimension ao = 2.8664Å):
110 0.24669 34.41 18.474 −1.6 0.9 1142.2 4.290 12 0.9577 0.001803B 101.5C
200 0.34887 53.06 15.218 −1.6 0.9 745.0 2.805 6 0.9172 0.001803B 20.73C
211 0.42728 78.20 13.133 −1.6 0.8 534.6 9.388 24 0.8784 0.001803B 190.8C
(γ iron, face-centered cubic, unit-cell dimension a o = 3.60Å):
111 0.24056 33.44 18.687 −1.6 0.9 4684.4 4.554 8 0.9597 0.0004594B 75.24C
200 0.27778 39.52 17.422 −1.6 0.9 4018.3 3.317 6 0.9467 0.0004594B 34.78C
220 0.39284 64.15 14.004 −1.6 0.8 2472.0 3.920 12 0.8962 0.0004594B 47.88C
A
Data from “International Tables for X-Ray Crystallography,” Physical and Chemical Tables, Vol III, Kynoch Press, Birmingham, England, 1962, pp. 60, 61, 210, 213;
Weighted Kα1 and Kα2 value used (λ = 2.29092Å).
B
Temperature factor (T = e−2M) where M = B(sin 2 θ)/λ2 and 2B = 0.71. Also N is the reciprocal of the unit-cell volume.
C
Calculated intensity includes the variables listed that change with X-ray diffraction peak position.

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 E975 − 22
TABLE 2 Calculated Theoretical Intensities Using Molybdenum Kα RadiationA
2
hkl Sinθ/λ θ f ∆f' ∆f9 /F/ LP P TB N2 B RC
(α iron, body-centered cubic, unit-cell dimension ao = 2.8664Å):
110 0.24669 10.10 18.474 0.4 1.0 1428.9 62.15 12 0.9577 0.001803 1840
200 0.34887 14.36 15.218 0.4 0.9 978.9 29.71 6 0.9172 0.001803 288.6
211 0.42728 17.68 13.133 0.4 0.9 735.8 18.95 24 0.8784 0.001803 530.0
220 0.49338 20.53 11.652 0.3 0.9 574.6 13.62 12 0.8413 0.001803 142.5
310 0.55161 23.08 10.542 0.3 0.9 473.4 10.47 24 0.8057 0.001803 172.8
222 0.60426 25.43 9.685 0.3 0.9 402.0 8.396 8 0.7716 0.001803 37.56
321 0.65268 27.64 9.012 0.3 0.9 350.1 6.949 48 0.7390 0.001803 155.6
400 0.69774 29.73 8.480 0.3 0.9 311.6 5.892 6 0.7078 0.001803 14.06
330 0.74006 31.73 8.054 0.3 0.9 282.4 5.099 12 0.6778 0.001803 21.12
411 24 42.23
420 0.78010 33.67 7.713 0.3 0.9 260.1 4.489 24 0.6492 0.001803 32.80
332 0.81817 35.55 7.437 0.3 0.9 242.7 4.017 24 0.6217 0.001803 26.23
422 0.85455 37.40 7.211 0.3 0.9 228.9 3.647 24 0.5954 0.001803 21.51
431 0.88945 39.21 7.022 0.3 0.9 217.7 3.360 48 0.5702 0.001803 36.10
510 24 18.05
521 0.95542 42.77 6.719 0.3 0.9 200.3 2.972 48 0.5230 0.001803 26.94
440 0.98675 44.53 6.591 0.3 0.9 193.2 2.853 12 0.5009 0.001803 5.97
433 1.01712 46.29 6.472 0.3 0.9 186.7 2.775 24 0.4797 0.001803 10.75
530 24 10.75
442 1.04661 48.06 6.357 0.3 0.9 180.5 2.735 24 0.4594 0.001803 9.81
600 6 2.45
532 1.07529 49.84 6.244 0.3 0.9 174.5 2.730 48 0.4400 0.001803 18.14
611 24 9.07
620 1.10322 51.63 6.133 0.3 0.8 168.1 2.759 24 0.4214 0.001803 8.46
541 1.13047 53.46 6.022 0.3 0.8 162.4 2.822 48 0.4036 0.001803 16.01
622 1.15707 55.32 5.913 0.3 0.8 157.0 2.922 24 0.3865 0.001803 7.67
631 1.18307 57.22 5.805 0.3 0.8 151.6 3.061 48 0.3702 0.001803 14.87
444 1.20852 59.19 5.700 0.3 0.8 146.6 3.245 8 0.3545 0.001803 2.43
543 1.23344 61.23 5.598 0.3 0.8 141.7 3.484 48 0.3395 0.001803 14.51
550 12 3.63
710 24 7.25
640 1.25787 63.37 5.503 0.3 0.8 137.3 3.792 24 0.3252 0.001803 7.33
552 1.28183 65.64 5.414 0.3 0.8 133.2 4.193 24 0.3114 0.001803 7.53
633 24 7.53
721 48 15.05
642 1.30535 68.08 5.332 0.3 0.8 129.4 4.731 48 0.2983 0.001803 15.80
730 1.32846 70.76 5.258 0.3 0.8 126.1 5.489 24 0.2856 0.001803 8.55
651 1.37350 77.46 5.130 0.3 0.8 120.5 8.796 48 0.2620 0.001803 24.03
732 48 24.03
(γ iron, face-centered cubic, unit-cell dimension a o = 3.60Å):
111 0.24056 9.84 18.687 0.4 1.0 5845.0 65.51 8 0.9597 0.0004594 1351
200 0.27778 11.39 17.422 0.4 1.0 5098.0 48.43 6 0.9467 0.0004594 644.3
220 0.39284 16.21 14.004 0.4 0.9 3332.6 22.88 12 0.8962 0.0004594 376.7
311 0.46064 19.11 12.355 0.3 0.9 2575.3 15.97 24 0.8601 0.0004594 390.0
222 0.48113 19.99 11.908 0.3 0.9 2397.5 14.44 8 0.8484 0.0004594 107.9
400 0.55556 23.26 10.472 0.3 0.9 1869.5 10.29 6 0.8032 0.0004594 42.59
331 0.60540 25.48 9.668 0.3 0.9 1602.7 8.358 24 0.7709 0.0004594 113.9
420 0.62113 26.20 9.438 0.3 0.9 1530.2 7.849 24 0.7604 0.0004594 100.7
422 0.68041 28.92 8.674 0.3 0.9 1301.5 6.270 24 0.7199 0.0004594 64.77
333 0.72169 30.86 8.231 0.3 0.9 1177.4 5.423 8 0.6909 0.0004594 16.21
511 24 48.64
440 0.78567 33.94 7.670 0.3 0.9 1029.3 4.414 12 0.6452 0.0004594 16.16
531 0.82168 35.73 7.414 0.3 0.9 965.1 3.978 48 0.6192 0.0004594 52.42
442 0.83333 36.32 7.339 946.6 3.854 24 0.6108 0.0004594 24.57
600 6 6.14
620 0.87841 38.63 7.080 0.3 0.9 884.4 3.444 24 0.5782 0.0004594 19.42
533 0.91076 40.34 6.918 0.3 0.9 846.6 3.214 24 0.5549 0.0004594 16.65
622 0.92128 40.90 6.869 0.3 0.9 835.3 3.149 24 0.5474 0.0004594 15.88
444 0.96225 43.15 6.691 0.3 0.9 794.9 2.943 8 0.5182 0.0004594 4.46
551 0.99187 44.82 6.571 0.3 0.9 768.3 2.837 24 0.4973 0.0004594 11.95
711 24 11.95
640 1.00154 45.38 6.533 0.3 0.9 760.0 2.811 24 0.4906 0.0004594 11.56
642 1.03935 47.62 6.385 0.3 0.9 728.0 2.742 48 0.4644 0.0004594 20.44
553 1.06683 49.30 6.278 0.3 0.9 705.3 2.728 24 0.4457 0.0004594 9.46
731 48 18.91
800 1.11111 52.15 6.101 0.3 0.8 665.8 2.773 6 0.4162 0.0004594 2.12
733 1.13685 53.90 5.997 0.3 0.8 644.7 2.842 24 0.3995 0.0004594 8.07
644 1.14531 54.48 5.962 0.3 0.8 637.6 2.873 24 0.3940 0.0004594 7.96
820 24 7.96
660 1.17851 56.88 5.824 0.3 0.8 610.3 3.033 12 0.3730 0.0004594 3.81
822 24 7.61
555 1.20281 58.74 5.723 0.3 0.8 590.7 3.199 8 0.3580 0.0004594 2.49
751 48 14.92
662 1.21081 59.37 5.691 0.3 0.8 584.5 3.264 24 0.3531 0.0004594 7.43

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 E975 − 22
TABLE 2 Continued
2
hkl Sinθ/λ θ f ∆f' ∆f9 /F/ LP P TB N2 B RC

840 1.24226 61.99 5.564 0.3 0.8 560.4 3.585 24 0.3343 0.0004594 7.41
753 1.26534 64.06 5.475 0.3 0.8 543.8 3.905 48 0.3209 0.0004594 15.03
911 24 7.51
842 1.27294 64.78 5.446 0.3 0.8 538.5 4.030 48 0.3165 0.0004594 15.15
664 1.30289 67.81 5.339 0.3 0.8 519.0 4.666 24 0.2996 0.0004594 8.00
931 1.32492 70.32 5.268 0.3 0.8 506.3 5.352 48 0.2876 0.0004594 17.18
844 1.36083 75.27 5.164 0.3 0.8 487.9 7.391 24 0.2685 0.0004594 10.68
755 1.38193 79.15 5.107 0.3 0.8 478.0 10.26 24 0.2577 0.0004594 13.93
771 24 13.93
933 24 13.93
A
Data from “International Tables for X-Ray Crystallography,” Physical and Chemical Tables, Vol. III, Kynoch Press, Birmingham, England, 1962, pp 60, 61, 210, 213;
Weight Kα1 and Kα2 value used (λ = 0.71069Å).
B
Temperature factor (T = e−2 M) where M = B(sin 2 θ)/λ2 and 2B = 0.71. Also N is the reciprocal of the unit-cell volume.
C
Calculated intensity, R, includes the variables listed that change with X-ray diffraction peak position.

4.3.7 The retained austenite content may be estimated from measurements of specimens containing about 2.5 %, 5 %, and
a number of ferrite and austenite intensity to R-value ratios 15 % by volume austenite in a medium carbon steel. These
using Eq 2 assuming no carbides are present. measures of precision will be degraded with increasing alloy
4.3.8 If the volume fraction of carbide has been determined, content and also near the minimum detectability limit of 2 %.
the volume fraction of austenite may be determined from Eq 3
for a single set of peaks or from Eq 4 for more than one set of 6.2 Bias—No bias estimate is available because there is no
peaks using the theoretical intensities listed in Table 1 for independent test method to determine an accepted reference
chromium radiation or in Table 2 for molybdenum radiation. value from retained austenite. Use of this test method produces
comparable values from one facility to another while utilizing
5. Example a variety of X-ray diffraction instruments.
5.1 Using chromium radiation, the integrated intensity (area
of peak above background) for ferrite peaks (200) and (211) 7. Report
and for retained austenite peaks (200) and (220) were deter-
7.1 For this test method, the accompanying report shall
mined. Values of R for each peak were obtained from Table 1.
contain the following:
5.1.1 The measured integrated intensities and values of R
are illustrated in Table 3. 7.1.1 Name of the organization and person performing the
5.1.2 From Eq 1 for the α (200) and γ (200) peaks: analysis.
1.00 7.1.2 Date the analysis was completed.
34.78 7.1.3 Material type.
Vγ 5 5 0.373 or 37.3 % retained austenite (5)
1.00 1.00 7.1.4 Specimen description, size, and location.
1
20.73 34.78 7.1.5 X ray system used for the analysis.
5.1.3 From Eq 2 for all four peaks: 7.1.6 Radiation used for the analysis.
½ ~ 0.0287510.02945! 7.1.7 Beam size or collimator used.
Vγ 5 5 0.373 (6)
½ ~ 0.0482410.04979! 1½ ~ 0.0287510.02945! 7.1.8 Depth where analysis was performed.
6. Precision and Bias 7.1.9 Specimen rotation (Yes / No ).
7.1.10 Specimen translation (Yes / No ).
6.1 Precision—On the basis of an interlaboratory test pro-
gram this test method produces an intralaboratory repeatability 7.1.11 The austenite and ferrite peaks used for the analysis.
of 3 % and an interlaboratory reproducibility of 4 % both at the 7.1.12 Approximate carbide volume percent, if determined.
95 % confidence level.3 These estimates were derived from 7.1.13 Carbide correction (Yes / No ).
7.1.14 Volume percent retained austenite.
3
Hinton, R. W., “Interlaboratory Evaluation of ASTM Practice for X-ray
Determination of Retained Austenite in Steel with Near-random Crystallographic 7.2 Any other information regarding the test procedures
Orientation” (Practice E975), Journal of Testing and Evaluation, Vol 15, No. 2 deemed necessary shall be based upon purchaser-testing labo-
March 1987, pp. 95–100.
ratory agreements.
TABLE 3 Measured Integrated Intensities and Values of K
8. Keywords
Peak − α (200) γ (200) γ(220) α (211)
I 1.00 1.00 1.41 9.50
8.1 austenite; crystallographic orientation; ferrite; marten-
R 20.73 34.78 47.88 190.8 site; retained austenite; X-ray diffraction
I:R 0.04824 0.02875 0.02945 0.0497

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