ASTM E112-96(2004)e1
(Test Method)Standard Test Methods for Determining Average Grain Size
Standard Test Methods for Determining Average Grain Size
SCOPE
1.1 These test methods cover the measurement of average grain size and include the comparison procedure, the planimetric (or Jeffries) procedure, and the intercept procedures. These test methods may also be applied to nonmetallic materials with structures having appearances similar to those of the metallic structures shown in the comparison charts. These test methods apply chiefly to single phase grain structures but they can be applied to determine the average size of a particular type of grain structure in a multiphase or multiconstituent specimen.
1.2 These test methods are used to determine the average grain size of specimens with a unimodal distribution of grain areas, diameters, or intercept lengths. These distributions are approximately log normal. These test methods do not cover methods to characterize the nature of these distributions. Characterization of grain size in specimens with duplex grain size distributions is described in Test Methods E 1181. Measurement of individual, very coarse grains in a fine grained matrix is described in Test Methods E 930.
1.3 These test methods deal only with determination of planar grain size, that is, characterization of the two-dimensional grain sections revealed by the sectioning plane. Determination of spatial grain size, that is, measurement of the size of the three-dimensional grains in the specimen volume, is beyond the scope of these test methods.
1.4 These test methods describe techniques performed manually using either a standard series of graded chart images for the comparison method or simple templates for the manual counting methods. Utilization of semi-automatic digitizing tablets or automatic image analyzers to measure grain size is described in Test Methods E 1382.
1.5 These test methods deal only with the recommended test methods and nothing in them should be construed as defining or establishing limits of acceptability or fitness of purpose of the materials tested.
1.6 The measured values are stated in SI units, which are regarded as standard. Equivalent inch-pound values, when listed, are in parentheses and may be approximate.
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.
1.7 The paragraphs appear in the following order:
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
e2
Designation: E 112 – 96 (Reapproved 2004)
Standard Test Methods for
Determining Average Grain Size
This standard is issued under the fixed designation E112; 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 (e) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
e NOTE—Reference (2) was editorially corrected in May 2006.
e NOTE— Equation A1.9 was editorially corrected in November 2006.
INTRODUCTION
These test methods of determination of average grain size in metallic materials are primarily
measuring procedures and, because of their purely geometric basis, are independent of the metal or
alloy concerned. In fact, the basic procedures may also be used for the estimation of average grain,
crystal, or cell size in nonmetallic materials. The comparison method may be used if the structure of
the material approaches the appearance of one of the standard comparison charts. The intercept and
planimetric methods are always applicable for determining average grain size. However, the
comparison charts cannot be used for measurement of individual grains.
1. Scope sizeofthethree-dimensionalgrainsinthespecimenvolume,is
beyond the scope of these test methods.
1.1 These test methods cover the measurement of average
1.4 These test methods describe techniques performed
grainsizeandincludethecomparisonprocedure,theplanimet-
manually using either a standard series of graded chart images
ric (or Jeffries) procedure, and the intercept procedures. These
for the comparison method or simple templates for the manual
testmethodsmayalsobeappliedtononmetallicmaterialswith
counting methods. Utilization of semi-automatic digitizing
structures having appearances similar to those of the metallic
tablets or automatic image analyzers to measure grain size is
structures shown in the comparison charts. These test methods
described in Test Methods E1382.
apply chiefly to single phase grain structures but they can be
1.5 Thesetestmethodsdealonlywiththerecommendedtest
applied to determine the average size of a particular type of
methods and nothing in them should be construed as defining
grain structure in a multiphase or multiconstituent specimen.
or establishing limits of acceptability or fitness of purpose of
1.2 These test methods are used to determine the average
the materials tested.
grain size of specimens with a unimodal distribution of grain
1.6 The measured values are stated in SI units, which are
areas, diameters, or intercept lengths. These distributions are
regarded as standard. Equivalent inch-pound values, when
approximately log normal. These test methods do not cover
listed, are in parentheses and may be approximate.
methods to characterize the nature of these distributions.
1.7 This standard does not purport to address all of the
Characterization of grain size in specimens with duplex grain
safety concerns, if any, associated with its use. It is the
size distributions is described in Test Methods E1181. Mea-
responsibility of the user of this standard to establish appro-
surement of individual, very coarse grains in a fine grained
priate safety and health practices and determine the applica-
matrix is described in Test Methods E930.
bility of regulatory limitations prior to use.
1.3 These test methods deal only with determination of
1.8 The paragraphs appear in the following order:
planar grain size, that is, characterization of the two-
Section Number
dimensional grain sections revealed by the sectioning plane.
Scope 1
Determinationofspatialgrainsize,thatis,measurementofthe
Referenced Documents 2
Terminology 3
Significance and Use 4
Generalities of Application 5
Sampling 6
These test methods are under the jurisdiction of ASTM Committee E04 on
Test Specimens 7
Metallography and are the direct responsibility of Subcommittee E04.08 on Grain
Calibration 8
Size.
Preparation of Photomicrographs 9
CurrenteditionapprovedMarch31,2006.PublishedNovember2004.Originally
e3 Comparison Procedure 10
approved in 1955. Last previous edition approved 1996 as E112–96 .
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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E 112 – 96 (2004)
3.2.2 grain—that area within the confines of the original
Planimetric (Jeffries) Procedure 11
General Intercept Procedures 12
(primary) boundary observed on the two-dimensional plane-
Heyn Linear Intercept Procedure 13
of-polish or that volume enclosed by the original (primary)
Circular Intercept Procedures 14
boundaryinthethree-dimensionalobject.Inmaterialscontain-
Hilliard Single-Circle Procedure 14.2
Abrams Three-Circle Procedure 14.3
ing twin boundaries, the twin boundaries are ignored, that is,
Statistical Analysis 15
the structure on either side of a twin boundary belongs to the
Specimens with Non-equiaxed Grain Shapes 16
grain.
Specimens Containing Two or More Phases or Constituents 17
Report 18
3.2.3 grain boundary intersection count—determination of
Precision and Bias 19
the number of times a test line cuts across, or is tangent to,
Keywords 20
Annexes:
grain boundaries (triple point intersections are considered as
Basis of ASTM Grain Size Numbers Annex
1- ⁄2 intersections).
A1
Equations for Conversions Among Various Grain Size Measurements Annex 3.2.4 graininterceptcount—determinationofthenumberof
A2
times a test line cuts through individual grains on the plane of
Austenite Grain Size, Ferritic and Austenitic Steels Annex
polish (tangent hits are considered as one half an interception;
A3
Fracture Grain Size Method Annex test lines that end within a grain are considered as one half an
A4
interception).
Requirements for Wrought Copper and Copper-Base Alloys Annex
3.2.5 intercept length—the distance between two opposed,
A5
Application to Special Situations Annex
adjacent grain boundary intersection points on a test line
A6
segment that crosses the grain at any location due to random
Appendixes:
Results of Interlaboratory Grain Size Determinations Appen- placement of the test line.
dix X1
3.3 Symbols:Symbols:
Referenced Adjuncts Appen-
dix X2
2. Referenced Documents
a = matrix grains in a two phase (constituent)
microstructure.
2.1 ASTM Standards:
A = test area.
E3 Practice for Preparation of Metallographic Specimens
—
= mean grain cross sectional area.
A
E7 Terminology Relating to Metallography
AI = grain elongation ratio or anisotropy index
E407 Practice for Microetching Metals and Alloys
,
for a longitudinally oriented plane.
E562 Practice for Determining Volume Fraction by Sys-
—
= mean planar grain diameter (Plate III).
tematic Manual Point Count
d
E691 Practice for Conducting an Interlaboratory Study to —
= mean spatial (volumetric) grain diameter.
D
Determine the Precision of a Test Method
f = Jeffriesmultiplierforplanimetricmethod.
E883 Guide for Reflected-Light Photomicrography
G = ASTM grain size number.
E930 Test Methods for Estimating the Largest Grain Ob-
= mean lineal intercept length.
,
served in a Metallographic Section (ALA Grain Size)
—
= mean lineal intercept length of the a
,
a
E1181 TestMethodsforCharacterizingDuplexGrainSizes
matrix phase in a two phase (constituent)
E1382 Test Methods for Determining Average Grain Size
microstructure.
Using Semiautomatic and Automatic Image Analysis
—
= mean lineal intercept length on a longitu-
,
,
2.2 ASTM Adjuncts:
dinally oriented surface for a non-
2.2.1 For a complete adjunct list, see Appendix X2
equiaxed grain structure.
—
= mean lineal intercept length on a trans-
3. Terminology ,
t
versely oriented surface for a non-
3.1 Definitions—For definitions of terms used in these test
equiaxed grain structure.
methods, see TerminologyE7.
—
= mean lineal intercept length on a planar
,
p
3.2 Definitions of Terms Specific to This Standard:
oriented surface for a non-equiaxed grain
3.2.1 ASTM grain size number—the ASTM grain size
structure.
number, G, was originally defined as:
, = base intercept length of 32.00 mm for
G21
defining the relationship between G and ,
N 52 (1)
AE
(and N ) for macroscopically or micro-
L
where N is the number of grains per square inch at 100X
AE
scopically determined grain size by the
magnification. To obtain the number per square millimetre at
intercept method.
1X, multiply by 15.50.
L = length of a test line.
M = magnification used.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or M = magnification used by a chart picture
b
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
series.
Standards volume information, refer to the standard’s Document Summary page on
n = number of fields measured.
the ASTM website.
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E 112 – 96 (2004)
consisting entirely, or principally, of a single phase. The test
N = numberof agrainsinterceptedbythetest
a
methods may also be used for any structures having appear-
line in a two phase (constituent) micro-
ances similar to those of the metallic structures shown in the
structure.
comparison charts. The three basic procedures for grain size
N = number of grains per mm at 1X.
A
N = number of a grains per mm at 1X in a estimation are:
Aa
two phase (constituent) microstructure.
4.1.1 Comparison Procedure—The comparison procedure
N = number of grains per inch at 100X.
AE
does not require counting of either grains, intercepts, or
N = N onalongitudinallyorientedsurfacefor
A, A
intersectionsbut,asthenamesuggests,involvescomparisonof
a non-equiaxed grain structure.
the grain structure to a series of graded images, either in the
N = N onatransverselyorientedsurfacefora
At A
form of a wall chart, clear plastic overlays, or an eyepiece
non-equiaxed grain structure.
reticle. There appears to be a general bias in that comparison
N = N on a planar oriented surface for a
Ap A
grain size ratings claim that the grain size is somewhat coarser
non-equiaxed grain structure.
( ⁄2 to 1 G number lower) than it actually is (see X1.3.5).
N = number of intercepts with a test line.
i
Repeatability and reproducibility of comparison chart ratings
N = number of grains completely within a test
Inside
are generally 61 grain size number.
circle.
4.1.2 Planimetric Procedure—The planimetric method in-
N = number of grains intercepted by the test
Intercepted
volves an actual count of the number of grains within a known
circle.
N = number of intercepts per unit length of area. The number of grains per unit area, N , is used to
A
L
test line. determine the ASTM grain size number, G. The precision of
N = N onalongitudinallyorientedsurfacefor the method is a function of the number of grains counted. A
L, L
a non-equiaxed grain structure.
precision of 60.25 grain size units can be attained with a
N = N onatransverselyorientedsurfacefora
reasonable amount of effort. Results are free of bias and
Lt L
non-equiaxed grain structure.
repeatability and reproducibility are less than 60.5 grain size
N = N on a planar oriented surface for a
Lp L
units.An accurate count does require marking off of the grains
non-equiaxed grain structure.
as they are counted.
P = number of grain boundary intersections
i
4.1.3 Intercept Procedure—The intercept method involves
with a test line.
an actual count of the number of grains intercepted by a test
P = number of grain boundary intersections
L
line or the number of grain boundary intersections with a test
per unit length of test line.
line, per unit length of test line, used to calculate the mean
P = P onalongitudinallyorientedsurfacefor
L, L
— —
lineal intercept length, ,. , is used to determine the ASTM
a non-equiaxed grain structure.
P = P onatransverselyorientedsurfacefora grainsizenumber, G.Theprecisionofthemethodisafunction
Lt L
non-equiaxed grain structure.
of the number of intercepts or intersections counted. A preci-
P = P on a planar oriented surface for a
sion of better than 60.25 grain size units can be attained with
Lp L
non-equiaxed grain structure.
a reasonable amount of effort. Results are free of bias;
Q = correction factor for comparison chart
repeatability and reproducibility are less than 60.5 grain size
ratings using a non-standard magnifica-
units. Because an accurate count can be made without need of
tion for microscopically determined grain
marking off intercepts or intersections, the intercept method is
sizes.
faster than the planimetric method for the same level of
Q = correction factor for comparison chart
m
precision.
ratings using a non-standard magnifica-
4.2 For specimens consisting of equiaxed grains, the
tionformacroscopicallydeterminedgrain
method of comparing the specimen with a standard chart is
sizes.
most convenient and is sufficiently accurate for most commer-
s = standard deviation.
cial purposes. For higher degrees of accuracy in determining
S = grain boundary surface area to volume
V
averagegrainsize,theinterceptorplanimetricproceduresmay
ratio for a single phase structure.
be used. The intercept procedure is particularly useful for
S = grain boundary surface area to volume
Va
structures consisting of elongated grains.
ratio for a two phase (constituent) struc-
4.3 In case of dispute, the intercept procedure shall be the
ture.
referee procedure in all cases.
t = students’ t multiplier for determination of
the confidence interval. 4.4 Noattemptshouldbemadetoestimatetheaveragegrain
V = volume fraction of the a phase in a two
size of heavily cold-worked material. Partially recrystallized
Va
phase (constituent) microstructure.
wroughtalloysandlightlytomoderatelycold-workedmaterial
95 % CI = 95% confidence interval.
may be considered as consisting of non-equiaxed grains, if a
% RA = percent relative accuracy.
grain size measurement is necessary.
4.5 Individual grain measurements should not be made
4. Significance and Use
based on the standard comparison charts. These charts were
4.1 These test methods cover procedures for estimating and constructed to reflect the typical log-normal distribution of
rules for expressing the average grain size of all metals grain sizes that result when a plane is passed through a
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E 112 – 96 (2004)
three-dimensional array of grains. Because they show a distri- the test method. If the grain structure is not equiaxed, but
bution of grain dimensions, ranging from very small to very elongated, then grain size measurements on specimens with
large, depending on the relationship of the planar section and different orientations will vary. In this case, the grain size
the three-dimensional array of grains, the charts are not should be ev
...
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