1、Designation: E112 10Standard Test Methods forDetermining Average Grain Size1This standard is issued under the fixed designation E112; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parenthese
2、s indicates the year of last reapproval. Asuperscript 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.INTRODUCTIONThese test methods of determination of average grain size in metallic mate
3、rials are primarilymeasuring procedures and, because of their purely geometric basis, are independent of the metal oralloy 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 i
4、f the structure ofthe material approaches the appearance of one of the standard comparison charts. The intercept andplanimetric methods are always applicable for determining average grain size. However, thecomparison charts cannot be used for measurement of individual grains.1. Scope1.1 These test m
5、ethods cover the measurement of averagegrain size and include the comparison procedure, the planimet-ric (or Jeffries) procedure, and the intercept procedures. Thesetest methods may also be applied to nonmetallic materials withstructures having appearances similar to those of the metallicstructures
6、shown in the comparison charts. These test methodsapply chiefly to single phase grain structures but they can beapplied to determine the average size of a particular type ofgrain structure in a multiphase or multiconstituent specimen.1.2 These test methods are used to determine the averagegrain size
7、 of specimens with a unimodal distribution of grainareas, diameters, or intercept lengths. These distributions areapproximately log normal. These test methods do not covermethods to characterize the nature of these distributions.Characterization of grain size in specimens with duplex grainsize distr
8、ibutions is described in Test Methods E1181. Mea-surement of individual, very coarse grains in a fine grainedmatrix is described in Test Methods E930.1.3 These test methods deal only with determination ofplanar grain size, that is, characterization of the two-dimensional grain sections revealed by t
9、he sectioning plane.Determination of spatial grain size, that is, measurement of thesize of the three-dimensional grains in the specimen volume, isbeyond the scope of these test methods.1.4 These test methods describe techniques performedmanually using either a standard series of graded chart images
10、for the comparison method or simple templates for the manualcounting methods. Utilization of semi-automatic digitizingtablets or automatic image analyzers to measure grain size isdescribed in Test Methods E1382.1.5 These test methods deal only with the recommended testmethods and nothing in them sho
11、uld be construed as definingor establishing limits of acceptability or fitness of purpose ofthe materials tested.1.6 The measured values are stated in SI units, which areregarded as standard. Equivalent inch-pound values, whenlisted, are in parentheses and may be approximate.1.7 This standard does n
12、ot purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.1.8 The paragraphs appear in the follow
13、ing order:Section NumberScope 1Referenced Documents 2Terminology 3Significance and Use 4Generalities of Application 5Sampling 6Test Specimens 7Calibration 8Preparation of Photomicrographs 9Comparison Procedure 10Planimetric (Jeffries) Procedure 11General Intercept Procedures 12Heyn Linear Intercept
14、Procedure 13Circular Intercept Procedures 14Hilliard Single-Circle Procedure 14.2Abrams Three-Circle Procedure 14.31These 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 Nov.
15、1, 2010. Published December 2010. Originallyapproved in 1955. Last previous edition approved 2004 as E112 96(2004)2. DOI:10.1520/E0112-10.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.Statistical Analysis 15Specimens with Non-equia
16、xed Grain Shapes 16Specimens Containing Two or More Phases or Constituents 17Report 18Precision and Bias 19Keywords 20Annexes:Basis of ASTM Grain Size Numbers AnnexA1Equations for Conversions Among Various Grain Size Measurements AnnexA2Austenite Grain Size, Ferritic and Austenitic Steels AnnexA3Fra
17、cture Grain Size Method AnnexA4Requirements for Wrought Copper and Copper-Base Alloys AnnexA5Application to Special Situations AnnexA6Appendixes:Results of Interlaboratory Grain Size Determinations Appen-dix X1Referenced Adjuncts Appen-dix X22. Referenced Documents2.1 ASTM Standards:2E3 Guide for Pr
18、eparation of Metallographic SpecimensE7 Terminology Relating to MetallographyE407 Practice for Microetching Metals and AlloysE562 Test Method for Determining Volume Fraction bySystematic Manual Point CountE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Metho
19、dE883 Guide for ReflectedLight PhotomicrographyE930 Test Methods for Estimating the Largest Grain Ob-served in a Metallographic Section (ALA Grain Size)E1181 Test Methods for Characterizing Duplex Grain SizesE1382 Test Methods for Determining Average Grain SizeUsing Semiautomatic and Automatic Image
20、 Analysis2.2 ASTM Adjuncts:2.2.1 For a complete adjunct list, see Appendix X23. Terminology3.1 DefinitionsFor definitions of terms used in these testmethods, see Terminology E7.3.2 Definitions of Terms Specific to This Standard:3.2.1 ASTM grain size numberthe ASTM grain sizenumber, G, was originally
21、 defined as:NAE5 2G21(1)where NAEis the number of grains per square inch at 100Xmagnification. To obtain the number per square millimetre at1X, multiply by 15.50.3.2.2 grainthat area within the confines of the original(primary) boundary observed on the two-dimensional plane-of-polish or that volume
22、enclosed by the original (primary)boundary in the three-dimensional object. In materials contain-ing twin boundaries, the twin boundaries are ignored, that is,the structure on either side of a twin boundary belongs to thegrain.3.2.3 grain boundary intersection countdetermination ofthe number of time
23、s a test line cuts across, or is tangent to,grain boundaries (triple point intersections are considered as1-12 intersections).3.2.4 grain intercept countdetermination of the number oftimes a test line cuts through individual grains on the plane ofpolish (tangent hits are considered as one half an in
24、terception;test lines that end within a grain are considered as one half aninterception).3.2.5 intercept lengththe distance between two opposed,adjacent grain boundary intersection points on a test linesegment that crosses the grain at any location due to randomplacement of the test line.3.3 Symbols
25、:Symbols:a = matrix grains in a two phase (constituent)microstructure.A = test area.A= mean grain cross sectional area.AI,= grain elongation ratio or anisotropy indexfor a longitudinally oriented plane.d= mean planar grain diameter (Plate III).D= mean spatial (volumetric) grain diameter.f = Jeffries
26、 multiplier for planimetric method.G = ASTM grain size number.,= mean lineal intercept length.,a= mean lineal intercept length of the amatrix phase in a two phase (constituent)microstructure.,= mean lineal intercept length on a longitu-dinally oriented surface for a non-equiaxed grain structure.,t=
27、mean lineal intercept length on a trans-versely oriented surface for a non-equiaxed grain structure.,p= mean lineal intercept length on a planaroriented surface for a non-equiaxed grainstructure.,0= base intercept length of 32.00 mm fordefining the relationship between G and ,(and NL) for macroscopi
28、cally or micro-scopically determined grain size by theintercept method.L = length of a test line.M = magnification used.Mb= magnification used by a chart pictureseries.n = number of fields measured.Na= number of a grains intercepted by the testline in a two phase (constituent) micro-structure.NA= nu
29、mber of grains per mm2at 1X.NAa= number of a grains per mm2at 1X in atwo phase (constituent) microstructure.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the stan
30、dards Document Summary page onthe ASTM website.E112 102NAE= number of grains per inch2at 100X.NA,= NAon a longitudinally oriented surface fora non-equiaxed grain structure.NAt= NAon a transversely oriented surface for anon-equiaxed grain structure.NAp= NAon a planar oriented surface for anon-equiaxe
31、d grain structure.Ni= number of intercepts with a test line.NInside= number of grains completely within a testcircle.NIntercepted= number of grains intercepted by the testcircle.NL= number of intercepts per unit length oftest line.NL,= NLon a longitudinally oriented surface fora non-equiaxed grain s
32、tructure.NLt= NLon a transversely oriented surface for anon-equiaxed grain structure.NLp= NLon a planar oriented surface for anon-equiaxed grain structure.Pi= number of grain boundary intersectionswith a test line.PL= number of grain boundary intersectionsper unit length of test line.PL,= PLon a lon
33、gitudinally oriented surface fora non-equiaxed grain structure.PLt= PLon a transversely oriented surface for anon-equiaxed grain structure.PLp= PLon a planar oriented surface for anon-equiaxed grain structure.Q = correction factor for comparison chartratings using a non-standard magnifica-tion for m
34、icroscopically determined grainsizes.Qm= correction factor for comparison chartratings using a non-standard magnifica-tion for macroscopically determined grainsizes.s = standard deviation.SV= grain boundary surface area to volumeratio for a single phase structure.SVa= grain boundary surface area to
35、volumeratio for a two phase (constituent) struc-ture.t = students t multiplier for determination ofthe confidence interval.VVa= volume fraction of the a phase in a twophase (constituent) microstructure.95 % CI = 95 % confidence interval.% RA = percent relative accuracy.4. Significance and Use4.1 The
36、se test methods cover procedures for estimating andrules for expressing the average grain size of all metalsconsisting entirely, or principally, of a single phase. The testmethods may also be used for any structures having appear-ances similar to those of the metallic structures shown in thecomparis
37、on charts. The three basic procedures for grain sizeestimation are:4.1.1 Comparison ProcedureThe comparison proceduredoes not require counting of either grains, intercepts, orintersections but, as the name suggests, involves comparison ofthe grain structure to a series of graded images, either in th
38、eform of a wall chart, clear plastic overlays, or an eyepiecereticle. There appears to be a general bias in that comparisongrain size ratings claim that the grain size is somewhat coarser(12 to 1 G number lower) than it actually is (see X1.3.5).Repeatability and reproducibility of comparison chart r
39、atingsare generally 61 grain size number.4.1.2 Planimetric ProcedureThe planimetric method in-volves an actual count of the number of grains within a knownarea. The number of grains per unit area, NA, is used todetermine the ASTM grain size number, G. The precision ofthe method is a function of the
40、number of grains counted. Aprecision of 60.25 grain size units can be attained with areasonable amount of effort. Results are free of bias andrepeatability and reproducibility are less than 60.5 grain sizeunits. An accurate count does require marking off of the grainsas they are counted.4.1.3 Interc
41、ept ProcedureThe intercept method involvesan actual count of the number of grains intercepted by a testline or the number of grain boundary intersections with a testline, per unit length of test line, used to calculate the meanlineal intercept length, ,. ,is used to determine the ASTMgrain size numb
42、er, G. The precision of the method is a functionof the number of intercepts or intersections counted. A preci-sion of better than 60.25 grain size units can be attained witha reasonable amount of effort. Results are free of bias;repeatability and reproducibility are less than 60.5 grain sizeunits. B
43、ecause an accurate count can be made without need ofmarking off intercepts or intersections, the intercept method isfaster than the planimetric method for the same level ofprecision.4.2 For specimens consisting of equiaxed grains, themethod of comparing the specimen with a standard chart ismost conv
44、enient and is sufficiently accurate for most commer-cial purposes. For higher degrees of accuracy in determiningaverage grain size, the intercept or planimetric procedures maybe used. The intercept procedure is particularly useful forstructures consisting of elongated grains.4.3 In case of dispute,
45、the intercept procedure shall be thereferee procedure in all cases.4.4 No attempt should be made to estimate the average grainsize of heavily cold-worked material. Partially recrystallizedwrought alloys and lightly to moderately cold-worked materialmay be considered as consisting of non-equiaxed gra
46、ins, if agrain size measurement is necessary.4.5 Individual grain measurements should not be madebased on the standard comparison charts. These charts wereconstructed to reflect the typical log-normal distribution ofgrain sizes that result when a plane is passed through athree-dimensional array of g
47、rains. Because they show a distri-bution of grain dimensions, ranging from very small to verylarge, depending on the relationship of the planar section andthe three-dimensional array of grains, the charts are notapplicable to measurement of individual grains.E112 1035. Generalities of Application5.1
48、 It is important, in using these test methods, to recognizethat the estimation of average grain size is not a precisemeasurement. A metal structure is an aggregate of three-dimensional crystals of varying sizes and shapes. Even if allthese crystals were identical in size and shape, the grain crossse
49、ctions, produced by a random plane (surface of observation)through such a structure, would have a distribution of areasvarying from a maximum value to zero, depending upon wherethe plane cuts each individual crystal. Clearly, no two fields ofobservation can be exactly the same.5.2 The size and location of grains in a microstructure arenormally completely random. No nominally random process ofpositioning a test pattern can improve this randomness, butrandom processes can yield poor representation by concentrat-ing measurements in part of a specimen. Represe
