ASTM E112-96(2004)e2
(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
´2
Designation: E112 – 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 (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
´ NOTE—Reference (2) was editorially corrected in May 2006.
´ 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
Current edition approved Nov. 4, 2004. Published November 2004. Originally
´3 Comparison Procedure 10
approved in 1955. Last previous edition approved 1996 as E112–96 . DOI:
Planimetric (Jeffries) Procedure 11
10.1520/E0112-96R04E02.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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E112 – 96 (2004)
of-polish or that volume enclosed by the original (primary)
General Intercept Procedures 12
Heyn Linear Intercept Procedure 13
boundaryinthethree-dimensionalobject.Inmaterialscontain-
Circular Intercept Procedures 14
ing twin boundaries, the twin boundaries are ignored, that is,
Hilliard Single-Circle Procedure 14.2
the structure on either side of a twin boundary belongs to the
Abrams Three-Circle Procedure 14.3
Statistical Analysis 15
grain.
Specimens with Non-equiaxed Grain Shapes 16
3.2.3 grain boundary intersection count—determination of
Specimens Containing Two or More Phases or Constituents 17
Report 18
the number of times a test line cuts across, or is tangent to,
Precision and Bias 19
grain boundaries (triple point intersections are considered as
Keywords 20
1- ⁄2 intersections).
Annexes:
Basis of ASTM Grain Size Numbers Annex
3.2.4 graininterceptcount—determinationofthenumberof
A1
times a test line cuts through individual grains on the plane of
Equations for Conversions Among Various Grain Size Measurements Annex
A2
polish (tangent hits are considered as one half an interception;
Austenite Grain Size, Ferritic and Austenitic Steels Annex
test lines that end within a grain are considered as one half an
A3
Fracture Grain Size Method Annex interception).
A4
3.2.5 intercept length—the distance between two opposed,
Requirements for Wrought Copper and Copper-Base Alloys Annex
adjacent grain boundary intersection points on a test line
A5
Application to Special Situations Annex
segment that crosses the grain at any location due to random
A6
placement of the test line.
Appendixes:
Results of Interlaboratory Grain Size Determinations Appen-
3.3 Symbols:Symbols:
dix X1
Referenced Adjuncts Appen-
dix X2
a = matrix grains in a two phase (constituent)
microstructure.
2. Referenced Documents
A = test area.
2.1 ASTM Standards:
—
= mean grain cross sectional area.
A
E3 Guide for Preparation of Metallographic Specimens
AI = grain elongation ratio or anisotropy index
,
E7 Terminology Relating to Metallography
for a longitudinally oriented plane.
E407 Practice for Microetching Metals and Alloys
—
= mean planar grain diameter (Plate III).
d
E562 Test Method for Determining Volume Fraction by
—
= mean spatial (volumetric) grain diameter.
Systematic Manual Point Count
D
E691 Practice for Conducting an Interlaboratory Study to
f = Jeffriesmultiplierforplanimetricmethod.
Determine the Precision of a Test Method
G = ASTM grain size number.
—
E883 Guide for Reflected−Light Photomicrography = mean lineal intercept length.
,
E930 Test Methods for Estimating the Largest Grain Ob-
—
= mean lineal intercept length of the a
,
a
served in a Metallographic Section (ALA Grain Size)
matrix phase in a two phase (constituent)
E1181 Test Methods for Characterizing Duplex Grain Sizes
microstructure.
E1382 Test Methods for Determining Average Grain Size —
= mean lineal intercept length on a longitu-
,
,
Using Semiautomatic and Automatic Image Analysis
dinally oriented surface for a non-
2.2 ASTM Adjuncts:
equiaxed grain structure.
2.2.1 For a complete adjunct list, see Appendix X2 —
= mean lineal intercept length on a trans-
,
t
versely oriented surface for a non-
3. Terminology
equiaxed grain structure.
—
3.1 Definitions—For definitions of terms used in these test = mean lineal intercept length on a planar
,
p
oriented surface for a non-equiaxed grain
methods, see Terminology E7.
3.2 Definitions of Terms Specific to This Standard: structure.
, = base intercept length of 32.00 mm for
3.2.1 ASTM grain size number—the ASTM grain size
defining the relationship between G and ,
number, G, was originally defined as:
(and N ) for macroscopically or micro-
G21 L
N 52 (1)
AE
scopically determined grain size by the
where N is the number of grains per square inch at 100X
intercept method.
AE
magnification. To obtain the number per square millimetre at
L = length of a test line.
1X, multiply by 15.50.
M = magnification used.
3.2.2 grain—that area within the confines of the original M = magnification used by a chart picture
b
(primary) boundary observed on the two-dimensional plane- series.
n = number of fields measured.
N = numberof agrainsinterceptedbythetest
a
For referenced ASTM standards, visit the ASTM website, www.astm.org, or line in a two phase (constituent) micro-
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
structure.
Standards volume information, refer to the standard’s Document Summary page on 2
N = number of grains per mm at 1X.
A
the ASTM website.
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E112 – 96 (2004)
methods may also be used for any structures having appear-
N = number of a grains per mm at 1X in a
Aa
ances similar to those of the metallic structures shown in the
two phase (constituent) microstructure.
comparison charts. The three basic procedures for grain size
N = number of grains per inch at 100X.
AE
N = N onalongitudinallyorientedsurfacefor estimation are:
A, A
a non-equiaxed grain structure. 4.1.1 Comparison Procedure—The comparison procedure
N = N onatransverselyorientedsurfacefora
does not require counting of either grains, intercepts, or
At A
non-equiaxed grain structure.
intersectionsbut,asthenamesuggests,involvescomparisonof
N = N on a planar oriented surface for a
Ap A the grain structure to a series of graded images, either in the
non-equiaxed grain structure.
form of a wall chart, clear plastic overlays, or an eyepiece
N = number of intercepts with a test line.
i
reticle. There appears to be a general bias in that comparison
N = number of grains completely within a test
Inside
grain size ratings claim that the grain size is somewhat coarser
circle.
( ⁄2 to 1 G number lower) than it actually is (see X1.3.5).
N = number of grains intercepted by the test
Intercepted
Repeatability and reproducibility of comparison chart ratings
circle.
are generally 61 grain size number.
N = number of intercepts per unit length of
L
4.1.2 Planimetric Procedure—The planimetric method in-
test line.
volves an actual count of the number of grains within a known
N = N onalongitudinallyorientedsurfacefor
L, L
area. The number of grains per unit area, N , is used to
A
a non-equiaxed grain structure.
determine the ASTM grain size number, G. The precision of
N = N onatransverselyorientedsurfacefora
Lt L
the method is a function of the number of grains counted. A
non-equiaxed grain structure.
precision of 60.25 grain size units can be attained with a
N = N on a planar oriented surface for a
Lp L
reasonable amount of effort. Results are free of bias and
non-equiaxed grain structure.
repeatability and reproducibility are less than 60.5 grain size
P = number of grain boundary intersections
i
units.An accurate count does require marking off of the grains
with a test line.
as they are counted.
P = number of grain boundary intersections
L
per unit length of test line. 4.1.3 Intercept Procedure—The intercept method involves
P = P onalongitudinallyorientedsurfacefor an actual count of the number of grains intercepted by a test
L, L
a non-equiaxed grain structure. line or the number of grain boundary intersections with a test
P = P onatransverselyorientedsurfacefora
line, per unit length of test line, used to calculate the mean
Lt L
— —
non-equiaxed grain structure.
lineal intercept length, ,. , is used to determine the ASTM
P = P on a planar oriented surface for a
Lp L
grainsizenumber, G.Theprecisionofthemethodisafunction
non-equiaxed grain structure.
of the number of intercepts or intersections counted. A preci-
Q = correction factor for comparison chart
sion of better than 60.25 grain size units can be attained with
ratings using a non-standard magnifica-
a reasonable amount of effort. Results are free of bias;
tion for microscopically determined grain
repeatability and reproducibility are less than 60.5 grain size
sizes.
units. Because an accurate count can be made without need of
Q = correction factor for comparison chart
m
marking off intercepts or intersections, the intercept method is
ratings using a non-standard magnifica-
faster than the planimetric method for the same level of
tionformacroscopicallydeterminedgrain
precision.
sizes.
4.2 For specimens consisting of equiaxed grains, the
s = standard deviation.
method of comparing the specimen with a standard chart is
S = grain boundary surface area to volume
V
most convenient and is sufficiently accurate for most commer-
ratio for a single phase structure.
cial purposes. For higher degrees of accuracy in determining
S = grain boundary surface area to volume
Va
averagegrainsize,theinterceptorplanimetricproceduresmay
ratio for a two phase (constituent) struc-
be used. The intercept procedure is particularly useful for
ture.
structures consisting of elongated grains.
t = students’ t multiplier for determination of
the confidence interval. 4.3 In case of dispute, the intercept procedure shall be the
V = volume fraction of the a phase in a two
referee procedure in all cases.
Va
phase (constituent) microstructure.
4.4 Noattemptshouldbemadetoestimatetheaveragegrain
95 % CI = 95% confidence interval.
size of heavily cold-worked material. Partially recrystallized
% RA = percent relative accuracy.
wroughtalloysandlightlytomoderatelycold-workedmaterial
may be considered as consisting of non-equiaxed grains, if a
4. Significance and Use
grain size measurement is necessary.
4.1 These test methods cover procedures for estimating and 4.5 Individual grain measurements should not be made
rules for expressing the average grain size of all metals based on the standard comparison charts. These charts were
consisting entirely, or principally, of a single phase. The test constructed to reflect the typical log-normal distribution of
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E112 – 96 (2004)
grain sizes that result when a plane is passed through a any other, will be equivalent within the statistical precision of
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
...
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