1、Designation: E 1181 02 (Reapproved 2008)Standard Test Methods forCharacterizing Duplex Grain Sizes1This standard is issued under the fixed designation E 1181; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revisio
2、n. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.INTRODUCTIONTest methods are well established for the determination of average grain size, and estimation oflargest grain size, in products as
3、sumed to contain a single log-normal distribution of grain sizes. Thetest methods in this standard are set forth to characterize grain size in products with any otherdistributions of grain size.The term “duplex grain size” is chosen to describe any of these other distributions of grain size,because
4、of its common usage and familiarity. However, the use of that term does not imply that onlytwo grain size distributions exist.These test methods are equally aimed at describing the nature of the deviation from a singlelog-normal distribution of grain sizes, and at describing with reasonable accuracy
5、 the distributions ofsizes that actually exist.1. Scope1.1 These test methods provide simple guidelines for decid-ing whether a duplex grain size exists. The test methodsseparate duplex grain sizes into one of two distinct classes,then into specific types within those classes, and providesystems for
6、 grain size characterization of each type.1.2 UnitsThe values stated in SI units are to be regardedas standard. No other units of measurement are included in thisstandard.1.3 This standard may involve hazardous materials, opera-tions, and equipment. This standard does not purport toaddress all of th
7、e safety concerns associated with its use. It isthe responsibility of the user of this standard to consultappropriate safety and health practices and determine theapplicability of regulatory limitations prior to its use.2. Referenced Documents2.1 ASTM Standards:E3 Guide for Preparation of Metallogra
8、phic SpecimensE7 Terminology Relating to MetallographyE112 Test Methods for Determining Average Grain SizeE 407 Practice for Microetching Metals and AlloysE 562 Test Method for Determining Volume Fraction bySystematic Manual Point CountE 883 Guide for ReflectedLight PhotomicrographyE 930 Test Method
9、s for Estimating the Largest Grain Ob-served in a Metallographic Section (ALA Grain Size)2.2 ASTM Adjuncts:Comparison Chart for Estimation of Area Fractions23. Terminology3.1 Definitions:3.1.1 All terms used in these test methods are either definedin Terminology E7, or are discussed in 3.2.3.2 Defin
10、itions of Terms Specific to This Standard:3.2.1 bands or bandingin grain size, alternating areas ofsignificantly different grain sizes. These areas are usuallyelongated in a direction parallel to the direction of working.3.2.2 grain sizeequivalent in meaning to the average of adistribution of grain
11、sizes.3.2.3 necklace or necklace structureindividual coarsegrains surrounded by rings of significantly finer grains.3.2.4 topologically varyingvarying nonrandomly, in somedefinable pattern; that pattern may be related to the shape of thespecimen or product being examined.4. Summary of Test Method4.1
12、 These test methods provide means for recognizing thepresence of duplex grain size.The test methods separate duplexgrain sizes into two classes (randomly varying, and topologi-cally varying), and define specific types of duplex grain sizeswithin these classes. The test methods provide means forestim
13、ating area fractions occupied by distinct grain sizes, andoffer existing standard methods (Test Methods E112, Test1These test methods are under the jurisdiction of ASTM Committee E04 onMetallography and are the direct responsibility of Subcommittee E04.08 on GrainSize.Current edition approved June 1
14、, 2008. Published October 2008. Originallyapproved in 1994. Last previous edition approved in 2002 as E 118102.2This comparison chart shows different area percentages of light grains amongdark grains. Available from ASTM Headquarters. Order Adjunct: ADJE1181.1Copyright ASTM International, 100 Barr H
15、arbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.Methods E 930) for determining grain size in specific identifiedareas. 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
16、 a procedure forstatistically determining the distribution of all the grain sizespresent in a duplex grain size specimen.5. Significance and Use5.1 Duplex grain size may occur in some metals and alloysas a result of their thermomechanical processing history. Forcomparison of mechanical properties wi
17、th metallurgical fea-tures, or for specification purposes, it may be important to beable to characterize grain size in such materials. Assigning anaverage grain size value to a duplex grain size specimen doesnot adequately characterize the appearance of that specimen,and may even misrepresent its ap
18、pearance. For example,averaging two distinctly different grain sizes may result inreporting a size that does not actually exist anywhere in thespecimen.5.2 These test methods may be applied to specimens orproducts containing randomly intermingled grains of two ormore significantly different sizes (h
19、enceforth referred to asrandom duplex grain size). Examples of random duplex grainsizes include: isolated coarse grains in a matrix of much finergrains, extremely wide distributions of grain sizes, and bimodaldistributions of grain size.5.3 These test methods may also be applied to specimens orprodu
20、cts containing grains of two or more significantly differ-ent sizes, but distributed in topologically varying patterns(henceforth referred to as topological duplex grain sizes).Examples of topological duplex grain sizes include: systematicvariation of grain size across the section of a product, neck
21、lacestructures, banded structures, and germinative grain growth inselected areas of critical strain.5.4 These test methods may be applied to specimens orproducts regardless of their state of recrystallization.5.5 Because these test methods describe deviations from asingle, log-normal distribution of
22、 grain sizes, and characterizepatterns of variation in grain size, the total specimen cross-section must be evaluated.5.6 These test methods are limited to duplex grain sizes asidentifiable within a single polished and etched metallurgicalspecimen. If duplex grain size is suspected in a product tool
23、arge to be polished and etched as a single specimen, macro-etching should be considered as a first step in evaluation. Theentire macroetched cross-section should be used as a basis forestimating area fractions occupied by distinct grain sizes, ifpossible. If microscopic examination is subsequently n
24、eces-sary, individual specimens must be taken to allow estimation ofarea fractions for the entire product cross-section, and to allowdetermination of grain sizes representing the entire cross-section as well.5.7 These test methods are intended to be applied to duplexgrain sizes. Duplex grain structu
25、res (for example, multiphasealloys) are not necessarily duplex in grain size, and as such arenot the subject of these methods. However, the test methodsdescribed here for area fraction estimation may be of use indescribing duplex grain structures.6. Apparatus6.1 Certain items may be helpful or neces
26、sary in applyingthe various procedures of these test methods. These items arebriefly described below, under the headings of the specificprocedures to which they apply.6.1.1 Comparison Procedure for Estimation of AreaFractionsThis procedure requires the use of a comparisonchart to improve the accurac
27、y of visual estimates of areafractions occupied by distinct grain sizes. This comparisonchart is shown in Fig. 13. The chart shows different areapercentages of light grains among dark grains.6.1.2 Point Count Procedure for Estimation of AreaFractionsThis procedure requires the use of a test grid on
28、atransparent overlay, or in a reticle, that can be superimposed onthe specimen image. The grid should consist of equally spacedpoints formed by the intersection of fine lines. Practice E 5623Leidheiser, H., Jr and Kim, D. K., “A Chemical Test for Identifying theFraction of Grains in the Surface of G
29、alvanized Steel Sheet That Have OrientationsApproximating (0001)Importance to Paint Adherence,”Metallurgical Transac-tions “B,” American Society for Metals, Metals Park, OH 44073, December, 1978,p. 590.FIG. 1 Comparison Chart for Estimation of Area Fractions1(Showing area percentages of light grains
30、 among dark grains)E 1181 02 (2008)2gives examples of such grids, as well as details on recom-mended grid spacing, and use of the grid.6.1.3 Planimetric Procedure for Estimation of AreaFractionsThis procedure requires the use of a planimeter, adevice for measuring the areas of irregular polygons. Th
31、eregions occupied by a distinct grain size are manually outlinedon a photomicrograph or transparent overlay. The area of eachof those regions is then measured by tracing its outline with theplanimeter.46.1.4 Test Methods E 930, Comparison Procedure for Esti-mation of Largest Grain Size Observed.6.1.
32、4.1 This procedure requires the use of a visual aid forestimation of the size of the largest grain found in a givenmetallographic section. That visual aid is shown in TestMethods E 930, and is available as anASTMAdjunct (see TestMethods E 930 for details).6.1.5 Test Methods E 930, Measuring Procedur
33、e for Esti-mation of Largest Grain Size Observed.6.1.5.1 This procedure may require the use of a measuringmicroscope eyepiece or measuring microscope reticle. Theseare available from microscope manufacturers.6.1.6 Test Methods E 930, Referee Procedure for Estimationof Largest Grain Size Observed.6.1
34、.6.1 This procedure requires the use of a test grid on atransparent overlay that can be superimposed on the specimenimage. The test grid consists of a square network of grid lines,with a recommended interline spacing of 5 mm. Use of the gridis described in Test Methods E 930.6.1.7 Test Methods E112,
35、 Comparison Procedure for De-termination of Average Grain Size.6.1.7.1 This procedure requires the use of grain size com-parison charts or overlay transparencies, or grain size compari-son reticles fitted into microscopes. Various comparison chartsand overlay transparencies are available as ASTM adj
36、uncts(see Test Methods E112for details).6.1.7.2 Grain size comparison reticles are available fromvarious manufacturers of microscopes.6.1.8 Test Methods E112, Intercept Procedures for Deter-mination of Average Grain Size,6.1.8.1 The Intercept Procedures of Test Methods E112require the use of pattern
37、s of test lines, usually on transparentoverlays. The use of these is described in detail in TestMethods E112.Atransparency of one such pattern is availableas an ASTM adjunct (see Test Methods E112for details).6.1.9 Statistical Determination of Grain Size Distribution:6.1.9.1 This procedure requires
38、the use of a test grid on atransparent overlay that can be superimposed on the specimenimage. The test grid consists of a series of fine, parallel lines,with an interline spacing of 5 mm. Use of the grid is describedin 8.7.6.1.9.2 This procedure may be carried out using manualmeasuring and counting
39、techniques, but as such, will be verylaborious and time-consuming. This procedure can be carriedout much more efficiently through the use of an automatedimage analysis system with an electronic pencil or cursor, orthrough the use of a semi-automated image analysis systemwith a digitizing tablet and
40、electronic pencil or cursor.5The useof this equipment is also described in 8.7.7. Sampling and Test Specimens7.1 Sampling:7.1.1 These test methods are intended to characterize pat-terns of variation in grain size, when they occur in a givenspecimen or product. To characterize these patterns accurate
41、ly,the entire cross-section of the specimen or product must beevaluated.7.1.2 If variations in grain size occur in a product too largeto be polished and etched as a single specimen, individualspecimens must be taken to allow estimation of area fractionsfor the entire product cross-section, and to al
42、low determinationof 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 thistest method (see 3.2 and 8.3) can be detected in a longitudinalspecimen orientation (that is, in a plane parallel to the directionof max
43、imum product deformation, during manufacture). Ac-cordingly, the longitudinal orientation is recommended, withone exception. If the specimen being examined is the fullcross-section of a round bar, the longitudinal section should notbe used to estimate the area fraction occupied by different grainsiz
44、es. That estimate can be made most accurately only on atransverse section. For a tubular product, estimates of areafractions made on longitudinal sections are reasonable approxi-mations of the same estimates made on transverse sections. Forall other products, area fraction estimates should be equall
45、yaccurate with either specimen orientation.7.2.2 Other specimen orientations may be used, providedthat their limitations are recognized. For instance, bandingpresent in a given specimen may not be easily recognizable ina transverse orientation.7.2.3 The specimen orientation used should be reportedal
46、ong with the duplex grain size characterization.8. Procedure8.1 Specimen PreparationPrepare specimens accordingto Methods E3, and etch specimens in accordance withPractice E 407. Etch specimens so that all grain boundaries aredistinct and easily visible.8.2 Preparation of PhotomicrographsIf photomic
47、ro-graphs are required for characterizing duplex grain size,prepare them in accordance with Practice E 883.8.3 Recognizing and Classifying Duplex Grain Size:8.3.1 A random duplex grain size is defined as any of thefollowing:8.3.1.1 The presence of randomly distributed individualcoarse grains, differ
48、ing in size by three or more ASTM grainsize numbers from the average size of the balance of the grains(henceforth referred to as the ALA (As Large As) condition).These individual coarse grains should comprise 5 % or less of4A Keuffel or, the presence of different grain sizes inspecific areas of a pr
49、oduct cross-section (for example, coarsegrains resulting from germinative grain growth at areas ofcritical strain), such that the grain size in those specific areasdiffers from the grain size in the bulk of the cross-section bythree or more ASTM grain size numbers (both conditionshenceforth referred to as the cross-section condition). Anexample photomicrograph of a cross-section condition appearsin Fig. A1.4.8.3.2.2 The presence of individual coarse grains, eachsurrounded by rings of finer grains, the coarse and fine grainsdiffering in size by three or more ASTM grain size
