ASTM E1181-02(2015)
(Test Method)Standard Test Methods for Characterizing Duplex Grain Sizes
Standard Test Methods for Characterizing Duplex Grain Sizes
SIGNIFICANCE AND USE
5.1 Duplex grain size may occur in some metals and alloys as a result of their thermomechanical processing history. For comparison of mechanical properties with metallurgical features, or for specification purposes, it may be important to be able to characterize grain size in such materials. Assigning an average grain size value to a duplex grain size specimen does not adequately characterize the appearance of that specimen, and may even misrepresent its appearance. For example, averaging two distinctly different grain sizes may result in reporting a size that does not actually exist anywhere in the specimen.
5.2 These test methods may be applied to specimens or products containing randomly intermingled grains of two or more significantly different sizes (henceforth referred to as random duplex grain size). Examples of random duplex grain sizes include: isolated coarse grains in a matrix of much finer grains, extremely wide distributions of grain sizes, and bimodal distributions of grain size.
5.3 These test methods may also be applied to specimens or products containing grains of two or more significantly different sizes, but distributed in topologically varying patterns (henceforth referred to as topological duplex grain sizes). Examples of topological duplex grain sizes include: systematic variation of grain size across the section of a product, necklace structures, banded structures, and germinative grain growth in selected areas of critical strain.
5.4 These test methods may be applied to specimens or products regardless of their state of recrystallization.
5.5 Because these test methods describe deviations from a single, log-normal distribution of grain sizes, and characterize patterns of variation in grain size, the total specimen cross-section must be evaluated.
5.6 These test methods are limited to duplex grain sizes as identifiable within a single polished and etched metallurgical specimen. If duplex grain size is suspected in a product too ...
SCOPE
1.1 These test methods provide simple guidelines for deciding whether a duplex grain size exists. The test methods separate duplex grain sizes into one of two distinct classes, then into specific types within those classes, and provide systems for grain size characterization of each type.
1.2 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety concerns associated with its use. It is the responsibility of the user of this standard to consult appropriate safety and health practices and determine the applicability of regulatory limitations prior to its use.
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Designation: E1181 − 02 (Reapproved 2015)
Standard Test Methods for
Characterizing Duplex Grain Sizes
This standard is issued under the fixed designation E1181; 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
Test methods are well established for the determination of average grain size, and estimation of
largest grain size, in products assumed to contain a single log-normal distribution of grain sizes. The
test methods in this standard are set forth to characterize grain size in products with any other
distributions of grain size.
The term “duplex grain size” is chosen to describe any of these other distributions of grain size,
because of its common usage and familiarity. However, the use of that term does not imply that only
two grain size distributions exist.
These test methods are equally aimed at describing the nature of the deviation from a single
log-normal distribution of grain sizes, and at describing with reasonable accuracy the distributions of
sizes that actually exist.
1. Scope E407 Practice for Microetching Metals and Alloys
E562 Test Method for Determining Volume Fraction by
1.1 These test methods provide simple guidelines for decid-
Systematic Manual Point Count
ing whether a duplex grain size exists. The test methods
E883 Guide for Reflected–Light Photomicrography
separate duplex grain sizes into one of two distinct classes,
E930 Test Methods for Estimating the Largest Grain Ob-
then into specific types within those classes, and provide
served in a Metallographic Section (ALA Grain Size)
systems for grain size characterization of each type.
2.2 ASTM Adjuncts:
1.2 Units—The values stated in SI units are to be regarded
Comparison Chart for Estimation of Area Fractions
as standard. No other units of measurement are included in this
3. Terminology
standard.
1.3 This standard may involve hazardous materials, 3.1 Definitions:
3.1.1 All terms used in these test methods are either defined
operations, and equipment. This standard does not purport to
in Terminology E7, or are discussed in 3.2.
address all of the safety concerns associated with its use. It is
3.2 Definitions of Terms Specific to This Standard:
the responsibility of the user of this standard to consult
3.2.1 bands or banding— in grain size, alternating areas of
appropriate safety and health practices and determine the
significantly different grain sizes. These areas are usually
applicability of regulatory limitations prior to its use.
elongated in a direction parallel to the direction of working.
2. Referenced Documents
3.2.2 grain size—equivalent in meaning to the average of a
2.1 ASTM Standards:
distribution of grain sizes.
E3 Guide for Preparation of Metallographic Specimens
3.2.3 necklace or necklace structure—individual coarse
E7 Terminology Relating to Metallography
grains surrounded by rings of significantly finer grains.
E112 Test Methods for Determining Average Grain Size
3.2.4 topologically varying—varying nonrandomly, in some
definable pattern; that pattern may be related to the shape of the
These test methods are under the jurisdiction of ASTM Committee E04 on
specimen or product being examined.
Metallography and are the direct responsibility of Subcommittee E04.08 on Grain
Size.
4. Summary of Test Method
Current edition approved Oct. 1, 2015. Published November 2015. Originally
ɛ1
approved in 1987. Last previous edition approved in 2008 as E1181–02(2008) .
4.1 These test methods provide means for recognizing the
DOI: 10.1520/E1181-02R15.
presence of duplex grain size. The test methods separate duplex
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on This comparison chart shows different area percentages of light grains among
the ASTM website. dark grains. Available from ASTM Headquarters. Order Adjunct: ADJE1181.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1181 − 02 (2015)
grain sizes into two classes (randomly varying, and topologi- does not adequately characterize the appearance of that
cally varying), and define specific types of duplex grain sizes specimen, and may even misrepresent its appearance. For
within these classes. The test methods provide means for example, averaging two distinctly different grain sizes may
estimating area fractions occupied by distinct grain sizes, and result in reporting a size that does not actually exist anywhere
offer existing standard methods (Test Methods E112, Test in the specimen.
Methods E930) for determining grain size in specific identified
5.2 These test methods may be applied to specimens or
areas. The test methods provide for reporting of specific,
products containing randomly intermingled grains of two or
distinctive information for each type of duplex grain size. And,
more significantly different sizes (henceforth referred to as
as an alternative, the test methods offer a procedure for
random duplex grain size). Examples of random duplex grain
statistically determining the distribution of all the grain sizes
sizes include: isolated coarse grains in a matrix of much finer
present in a duplex grain size specimen.
grains, extremely wide distributions of grain sizes, and bimodal
distributions of grain size.
5. Significance and Use
5.3 These test methods may also be applied to specimens or
5.1 Duplex grain size may occur in some metals and alloys
products containing grains of two or more significantly differ-
as a result of their thermomechanical processing history. For
ent sizes, but distributed in topologically varying patterns
comparison of mechanical properties with metallurgical
(henceforth referred to as topological duplex grain sizes).
features, or for specification purposes, it may be important to
Examples of topological duplex grain sizes include: systematic
be able to characterize grain size in such materials. Assigning
variation of grain size across the section of a product, necklace
an average grain size value to a duplex grain size specimen
structures, banded structures, and germinative grain growth in
selected areas of critical strain.
5.4 These test methods may be applied to specimens or
products regardless of their state of recrystallization.
5.5 Because these test methods describe deviations from a
single, log-normal distribution of grain sizes, and characterize
patterns of variation in grain size, the total specimen cross-
section must be evaluated.
5.6 These test methods are limited to duplex grain sizes as
identifiable within a single polished and etched metallurgical
specimen. If duplex grain size is suspected in a product too
large to be polished and etched as a single specimen, mac-
roetching should be considered as a first step in evaluation. The
entire macroetched cross-section should be used as a basis for
estimating area fractions occupied by distinct grain sizes, if
possible. If microscopic examination is subsequently
necessary, individual specimens must be taken to allow esti-
mation of area fractions for the entire product cross-section,
and to allow determination of grain sizes representing the
entire cross-section as well.
5.7 These test methods are intended to be applied to duplex
grain sizes. Duplex grain structures (for example, multiphase
alloys) are not necessarily duplex in grain size, and as such are
not the subject of these methods. However, the test methods
described here for area fraction estimation may be of use in
describing duplex grain structures.
6. Apparatus
6.1 Certain items may be helpful or necessary in applying
the various procedures of these test methods. These items are
briefly described below, under the headings of the specific
procedures to which they apply.
6.1.1 Comparison Procedure for Estimation of Area
Fractions—This procedure requires the use of a comparison
FIG. 1 Comparison Chart for Estimation of Area Fractions
(Showing area percentages of light grains among dark grains) chart to improve the accuracy of visual estimates of area
E1181 − 02 (2015)
fractions occupied by distinct grain sizes. This comparison Methods E112. A transparency of one such pattern is available
chart is shown in Fig. 1 . The chart shows different area as an ASTM adjunct (see Test Methods E112 for details).
percentages of light grains among dark grains. 6.1.9 Statistical Determination of Grain Size Distribution:
6.1.2 Point Count Procedure for Estimation of Area 6.1.9.1 This procedure requires the use of a test grid on a
Fractions—This procedure requires the use of a test grid on a transparent overlay that can be superimposed on the specimen
transparent overlay, or in a reticle, that can be superimposed on image. The test grid consists of a series of fine, parallel lines,
the specimen image. The grid should consist of equally spaced with an interline spacing of 5 mm. Use of the grid is described
points formed by the intersection of fine lines. Practice E562 in 8.7.
gives examples of such grids, as well as details on recom- 6.1.9.2 This procedure may be carried out using manual
mended grid spacing, and use of the grid. measuring and counting techniques, but as such, will be very
6.1.3 Planimetric Procedure for Estimation of Area laborious and time-consuming. This procedure can be carried
Fractions—This procedure requires the use of a planimeter, a out much more efficiently through the use of an automated
device for measuring the areas of irregular polygons. The image analysis system with an electronic pencil or cursor, or
regions occupied by a distinct grain size are manually outlined through the use of a semi-automated image analysis system
on a photomicrograph or transparent overlay. The area of each with a digitizing tablet and electronic pencil or cursor. The use
of those regions is then measured by tracing its outline with the of this equipment is also described in 8.7.
planimeter.
7. Sampling and Test Specimens
6.1.4 Test Methods E930, Comparison Procedure for Esti-
7.1 Sampling:
mation of Largest Grain Size Observed.
7.1.1 These test methods are intended to characterize pat-
6.1.4.1 This procedure requires the use of a visual aid for
terns of variation in grain size, when they occur in a given
estimation of the size of the largest grain found in a given
specimen or product. To characterize these patterns accurately,
metallographic section. That visual aid is shown in Test
the entire cross-section of the specimen or product must be
Methods E930, and is available as an ASTM Adjunct (see Test
evaluated.
Methods E930 for details).
7.1.2 If variations in grain size occur in a product too large
6.1.5 Test Methods E930, Measuring Procedure for Estima-
to be polished and etched as a single specimen, individual
tion of Largest Grain Size Observed.
specimens must be taken to allow estimation of area fractions
6.1.5.1 This procedure may require the use of a measuring
for the entire product cross-section, and to allow determination
microscope eyepiece or measuring microscope reticle. These
of grain sizes representing the entire cross-section as well.
are available from microscope manufacturers.
6.1.6 Test Methods E930, Referee Procedure for Estimation
7.2 Specimen Orientation:
of Largest Grain Size Observed.
7.2.1 All of the types of duplex grain size described in this
6.1.6.1 This procedure requires the use of a test grid on a
test method (see 3.2 and 8.3) can be detected in a longitudinal
transparent overlay that can be superimposed on the specimen
specimen orientation (that is, in a plane parallel to the direction
image. The test grid consists of a square network of grid lines,
of maximum product deformation, during manufacture).
with a recommended interline spacing of 5 mm. Use of the grid
Accordingly, the longitudinal orientation is recommended,
is described in Test Methods E930.
with one exception. If the specimen being examined is the full
6.1.7 Test Methods E112, Comparison Procedure for Deter-
cross-section of a round bar, the longitudinal section should not
mination of Average Grain Size.
be used to estimate the area fraction occupied by different grain
6.1.7.1 This procedure requires the use of grain size com-
sizes. That estimate can be made most accurately only on a
parison charts or overlay transparencies, or grain size compari-
transverse section. For a tubular product, estimates of area
son reticles fitted into microscopes. Various comparison charts
fractions made on longitudinal sections are reasonable approxi-
and overlay transparencies are available as ASTM adjuncts
mations of the same estimates made on transverse sections. For
(see Test Methods E112 for details).
all other products, area fraction estimates should be equally
6.1.7.2 Grain size comparison reticles are available from
accurate with either specimen orientation.
various manufacturers of microscopes.
7.2.2 Other specimen orientations may be used, provided
6.1.8 Test Methods E112, Intercept Procedures for Determi-
that their limitations are recognized. For instance, banding
nation of Average Grain Size,
present in a given specimen may not be easily recognizable in
6.1.8.1 The Intercept Procedures of Test Methods E112
a transverse orientation.
require the use of patterns of test lines, usually on transparent
7.2.3 The specimen orientation used should be reported
overlays. The use of these is described in detail in Test
along with the duplex grain size characterization.
8. Procedure
8.1 Specimen Preparation—Prepare specimens according to
Leidheiser, H., Jr. and Kim, D. K., “A Chemical Test for Identifying the
Methods E3, and etch specimens in accordance with Practice
Fraction of Grains in the Surface of Galvanized Steel Sheet That Have Orientations
Approximating (0001)—Importance to Paint Adherence,”Metallurgical Transac-
E407. Etch specimens so that all grain boundaries are distinct
tions “B,” American Society for Metals, Metals Park, OH 44073, December, 1978,
and easily visible.
p. 590.
A Keuffel & Esser Compensating Polar Planimeter available from drafting
equipment suppliers, or equivalent, has been found to be satisfactory for this A Zeiss Videoplan System, or its equivalent, has been found satisfactory for this
purpose. purpose.
E1181 − 02 (2015)
8.2 Preparation of Photomicrographs—If photomicro- procedure
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM 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.
´1
Designation: E1181 − 02 (Reapproved 2008) E1181 − 02 (Reapproved 2015)
Standard Test Methods for
Characterizing Duplex Grain Sizes
This standard is issued under the fixed designation E1181; 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.
ε NOTE—Footnote 1 was editorially corrected in February 2015.
INTRODUCTION
Test methods are well established for the determination of average grain size, and estimation of
largest grain size, in products assumed to contain a single log-normal distribution of grain sizes. The
test methods in this standard are set forth to characterize grain size in products with any other
distributions of grain size.
The term “duplex grain size” is chosen to describe any of these other distributions of grain size,
because of its common usage and familiarity. However, the use of that term does not imply that only
two grain size distributions exist.
These test methods are equally aimed at describing the nature of the deviation from a single
log-normal distribution of grain sizes, and at describing with reasonable accuracy the distributions of
sizes that actually exist.
1. Scope
1.1 These test methods provide simple guidelines for deciding whether a duplex grain size exists. The test methods separate
duplex grain sizes into one of two distinct classes, then into specific types within those classes, and provide systems for grain size
characterization of each type.
1.2 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this
standard.
1.3 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all
of the safety concerns associated with its use. It is the responsibility of the user of this standard to consult appropriate safety and
health practices and determine the applicability of regulatory limitations prior to its use.
2. Referenced Documents
2.1 ASTM Standards:
E3 Guide for Preparation of Metallographic Specimens
E7 Terminology Relating to Metallography
E112 Test Methods for Determining Average Grain Size
E407 Practice for Microetching Metals and Alloys
E562 Test Method for Determining Volume Fraction by Systematic Manual Point Count
E883 Guide for Reflected–Light Photomicrography
E930 Test Methods for Estimating the Largest Grain Observed in a Metallographic Section (ALA Grain Size)
2.2 ASTM Adjuncts:
Comparison Chart for Estimation of Area Fractions
These test methods are under the jurisdiction of ASTM Committee E04 on Metallography and are the direct responsibility of Subcommittee E04.08 on Grain Size.
Current edition approved June 1, 2008Oct. 1, 2015. Published October 2008 November 2015. Originally approved in 1987. Last previous edition approved in 20022008
ɛ1
as E1181E1181–02(2008) –02. DOI: 10.1520/E1181-02R08E01.10.1520/E1181-02R15.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
This comparison chart shows different area percentages of light grains among dark grains. Available from ASTM Headquarters. Order Adjunct: ADJE1181.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1181 − 02 (2015)
3. Terminology
3.1 Definitions:
3.1.1 All terms used in these test methods are either defined in Terminology E7, or are discussed in 3.2.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 bands or banding— in grain size, alternating areas of significantly different grain sizes. These areas are usually elongated
in a direction parallel to the direction of working.
3.2.2 grain size—equivalent in meaning to the average of a distribution of grain sizes.
3.2.3 necklace or necklace structure—individual coarse grains surrounded by rings of significantly finer grains.
3.2.4 topologically varying—varying nonrandomly, in some definable pattern; that pattern may be related to the shape of the
specimen or product being examined.
4. Summary of Test Method
4.1 These test methods provide means for recognizing the presence of duplex grain size. The test methods separate duplex grain
sizes into two classes (randomly varying, and topologically varying), and define specific types of duplex grain sizes within these
classes. The test methods provide means for estimating area fractions occupied by distinct grain sizes, and offer existing standard
methods (Test Methods E112, Test Methods E930) for determining grain size in specific identified areas. The test methods provide
for reporting of specific, distinctive information for each type of duplex grain size. And, as an alternative, the test methods offer
a procedure for statistically determining the distribution of all the grain sizes present in a duplex grain size specimen.
5. Significance and Use
5.1 Duplex grain size may occur in some metals and alloys as a result of their thermomechanical processing history. For
comparison of mechanical properties with metallurgical features, or for specification purposes, it may be important to be able to
FIG. 1 Comparison Chart for Estimation of Area Fractions
(Showing area percentages of light grains among dark grains)
E1181 − 02 (2015)
characterize grain size in such materials. Assigning an average grain size value to a duplex grain size specimen does not adequately
characterize the appearance of that specimen, and may even misrepresent its appearance. For example, averaging two distinctly
different grain sizes may result in reporting a size that does not actually exist anywhere in the specimen.
5.2 These test methods may be applied to specimens or products containing randomly intermingled grains of two or more
significantly different sizes (henceforth referred to as random duplex grain size). Examples of random duplex grain sizes include:
isolated coarse grains in a matrix of much finer grains, extremely wide distributions of grain sizes, and bimodal distributions of
grain size.
5.3 These test methods may also be applied to specimens or products containing grains of two or more significantly different
sizes, but distributed in topologically varying patterns (henceforth referred to as topological duplex grain sizes). Examples of
topological duplex grain sizes include: systematic variation of grain size across the section of a product, necklace structures,
banded structures, and germinative grain growth in selected areas of critical strain.
5.4 These test methods may be applied to specimens or products regardless of their state of recrystallization.
5.5 Because these test methods describe deviations from a single, log-normal distribution of grain sizes, and characterize
patterns of variation in grain size, the total specimen cross-section must be evaluated.
5.6 These test methods are limited to duplex grain sizes as identifiable within a single polished and etched metallurgical
specimen. If duplex grain size is suspected in a product too large to be polished and etched as a single specimen, macroetching
should be considered as a first step in evaluation. The entire macroetched cross-section should be used as a basis for estimating
area fractions occupied by distinct grain sizes, if possible. If microscopic examination is subsequently necessary, individual
specimens must be taken to allow estimation of area fractions for the entire product cross-section, and to allow determination of
grain sizes representing the entire cross-section as well.
5.7 These test methods are intended to be applied to duplex grain sizes. Duplex grain structures (for example, multiphase alloys)
are not necessarily duplex in grain size, and as such are not the subject of these methods. However, the test methods described here
for area fraction estimation may be of use in describing duplex grain structures.
6. Apparatus
6.1 Certain items may be helpful or necessary in applying the various procedures of these test methods. These items are briefly
described below, under the headings of the specific procedures to which they apply.
6.1.1 Comparison Procedure for Estimation of Area Fractions—This procedure requires the use of a comparison chart to
improve the accuracy of visual estimates of area fractions occupied by distinct grain sizes. This comparison chart is shown in Fig.
1 . The chart shows different area percentages of light grains among dark grains.
6.1.2 Point Count Procedure for Estimation of Area Fractions—This procedure requires the use of a test grid on a transparent
overlay, or in a reticle, that can be superimposed on the specimen image. The grid should consist of equally spaced points formed
by the intersection of fine lines. Practice E562 gives examples of such grids, as well as details on recommended grid spacing, and
use of the grid.
6.1.3 Planimetric Procedure for Estimation of Area Fractions—This procedure requires the use of a planimeter, a device for
measuring the areas of irregular polygons. The regions occupied by a distinct grain size are manually outlined on a
photomicrograph or transparent overlay. The area of each of those regions is then measured by tracing its outline with the
planimeter.
6.1.4 Test Methods E930, Comparison Procedure for Estimation of Largest Grain Size Observed.
6.1.4.1 This procedure requires the use of a visual aid for estimation of the size of the largest grain found in a given
metallographic section. That visual aid is shown in Test Methods E930, and is available as an ASTM Adjunct (see Test Methods
E930 for details).
6.1.5 Test Methods E930, Measuring Procedure for Estimation of Largest Grain Size Observed.
6.1.5.1 This procedure may require the use of a measuring microscope eyepiece or measuring microscope reticle. These are
available from microscope manufacturers.
6.1.6 Test Methods E930, Referee Procedure for Estimation of Largest Grain Size Observed.
6.1.6.1 This procedure requires the use of a test grid on a transparent overlay that can be superimposed on the specimen image.
The test grid consists of a square network of grid lines, with a recommended interline spacing of 5 mm. Use of the grid is described
in Test Methods E930.
6.1.7 Test Methods E112, Comparison Procedure for Determination of Average Grain Size.
6.1.7.1 This procedure requires the use of grain size comparison charts or overlay transparencies, or grain size comparison
reticles fitted into microscopes. Various comparison charts and overlay transparencies are available as ASTM adjuncts (see Test
Methods E112 for details).
Leidheiser, H., Jr. and Kim, D. K., “A Chemical Test for Identifying the Fraction of Grains in the Surface of Galvanized Steel Sheet That Have Orientations
Approximating (0001)—Importance to Paint Adherence,”Metallurgical Transactions “B,” American Society for Metals, Metals Park, OH 44073, December, 1978, p. 590.
A Keuffel & Esser Compensating Polar Planimeter available from drafting equipment suppliers, or equivalent, has been found to be satisfactory for this purpose.
E1181 − 02 (2015)
6.1.7.2 Grain size comparison reticles are available from various manufacturers of microscopes.
6.1.8 Test Methods E112, Intercept Procedures for Determination of Average Grain Size,
6.1.8.1 The Intercept Procedures of Test Methods E112 require the use of patterns of test lines, usually on transparent overlays.
The use of these is described in detail in Test Methods E112. A transparency of one such pattern is available as an ASTM adjunct
(see Test Methods E112 for details).
6.1.9 Statistical Determination of Grain Size Distribution:
6.1.9.1 This procedure requires the use of a test grid on a transparent overlay that can be superimposed on the specimen image.
The test grid consists of a series of fine, parallel lines, with an interline spacing of 5 mm. Use of the grid is described in 8.7.
6.1.9.2 This procedure may be carried out using manual measuring and counting techniques, but as such, will be very laborious
and time-consuming. This procedure can be carried out much more efficiently through the use of an automated image analysis
system with an electronic pencil or cursor, or through the use of a semi-automated image analysis system with a digitizing tablet
and electronic pencil or cursor. The use of this equipment is also described in 8.7.
7. Sampling and Test Specimens
7.1 Sampling:
7.1.1 These test methods are intended to characterize patterns of variation in grain size, when they occur in a given specimen
or product. To characterize these patterns accurately, the entire cross-section of the specimen or product must be evaluated.
7.1.2 If variations in grain size occur in a product too large to be polished and etched as a single specimen, individual specimens
must be taken to allow estimation of area fractions for the entire product cross-section, and to allow determination of grain sizes
representing the entire cross-section as well.
7.2 Specimen Orientation:
7.2.1 All of the types of duplex grain size described in this test method (see 3.2 and 8.3) can be detected in a longitudinal
specimen orientation (that is, in a plane parallel to the direction of maximum product deformation, during manufacture).
Accordingly, the longitudinal orientation is recommended, with one exception. If the specimen being examined is the full
cross-section of a round bar, the longitudinal section should not be used to estimate the area fraction occupied by different grain
sizes. That estimate can be made most accurately only on a transverse section. For a tubular product, estimates of area fractions
made on longitudinal sections are reasonable approximations of the same estimates made on transverse sections. For all other
products, area fraction estimates should be equally accurate with either specimen orientation.
7.2.2 Other specimen orientations may be used, provided that their limitations are recognized. For instance, banding present in
a given specimen may not be easily recognizable in a transverse orientation.
7.2.3 The specimen orientation used should be reported along with the duplex grain size charact
...
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