ASTM E112-1996(2004)e2 Standard Test Methods for Determining Average Grain Size《测定平均粒度的标准试验方法》.pdf

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1、Designation: E 112 96 (Reapproved 2004)e2Standard Test Methods forDetermining Average Grain Size1This standard is issued under the fixed designation E 112; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision.

2、A number in parentheses indicates the year of last reapproval. Asuperscript 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.e1NOTEReference (2) was editorially corrected in May 2006.e2NOT

3、E Equation A1.9 was editorially corrected in November 2006.INTRODUCTIONThese test methods of determination of average grain size in metallic materials are primarilymeasuring procedures and, because of their purely geometric basis, are independent of the metal oralloy concerned. In fact, the basic pr

4、ocedures 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 ofthe material approaches the appearance of one of the standard comparison charts. The intercept andplanimetric methods are always applicab

5、le for determining average grain size. However, thecomparison charts cannot be used for measurement of individual grains.1. Scope1.1 These test methods cover the measurement of averagegrain size and include the comparison procedure, the planimet-ric (or Jeffries) procedure, and the intercept procedu

6、res. Thesetest methods may also be applied to nonmetallic materials withstructures having appearances similar to those of the metallicstructures 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

7、particular type ofgrain structure in a multiphase or multiconstituent specimen.1.2 These test methods are used to determine the averagegrain size of specimens with a unimodal distribution of grainareas, diameters, or intercept lengths. These distributions areapproximately log normal. These test meth

8、ods do not covermethods to characterize the nature of these distributions.Characterization of grain size in specimens with duplex grainsize distributions is described in Test Methods E 1181. Mea-surement of individual, very coarse grains in a fine grainedmatrix is described in Test Methods E 930.1.3

9、 These test methods deal only with determination ofplanar 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 thesize of the three-dimensional grains in the specimen volume, isbeyond

10、 the scope of these test methods.1.4 These test methods describe techniques performedmanually using either a standard series of graded chart imagesfor the comparison method or simple templates for the manualcounting methods. Utilization of semi-automatic digitizingtablets or automatic image analyzer

11、s to measure grain size isdescribed in Test Methods E 1382.1.5 These test methods deal only with the recommended testmethods and nothing in them should be construed as definingor establishing limits of acceptability or fitness of purpose ofthe materials tested.1.6 The measured values are stated in S

12、I units, which areregarded as standard. Equivalent inch-pound values, whenlisted, are in parentheses and may be approximate.1.7 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appr

13、o-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.1.8 The paragraphs appear in the following order:Section NumberScope 1Referenced Documents 2Terminology 3Significance and Use 4Generalities of Application 5Sampling 6Test Specimens 7Calibrati

14、on 8Preparation of Photomicrographs 9Comparison Procedure 101These 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. 4, 2004. Published November 2004. Originallyapproved in

15、 1955. Last previous edition approved 1996 as E 112 96e3.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.Planimetric (Jeffries) Procedure 11General Intercept Procedures 12Heyn Linear Intercept Procedure 13Circular Intercept Procedure

16、s 14Hilliard Single-Circle Procedure 14.2Abrams Three-Circle Procedure 14.3Statistical Analysis 15Specimens with Non-equiaxed Grain Shapes 16Specimens Containing Two or More Phases or Constituents 17Report 18Precision and Bias 19Keywords 20Annexes:Basis of ASTM Grain Size Numbers AnnexA1Equations fo

17、r Conversions Among Various Grain Size Measurements AnnexA2Austenite Grain Size, Ferritic and Austenitic Steels AnnexA3Fracture Grain Size Method AnnexA4Requirements for Wrought Copper and Copper-Base Alloys AnnexA5Application to Special Situations AnnexA6Appendixes:Results of Interlaboratory Grain

18、Size Determinations Appen-dix X1Referenced Adjuncts Appen-dix X22. Referenced Documents2.1 ASTM Standards:2E3 Practice for Preparation of Metallographic SpecimensE7 Terminology Relating to MetallographyE 407 Practice for Microetching Metals and AlloysE 562 Practice for Determining Volume Fraction by

19、 Sys-tematic Manual Point CountE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE 883 Guide for Reflected-Light PhotomicrographyE 930 Test Methods for Estimating the Largest Grain Ob-served in a Metallographic Section (ALA Grain Size)E 1181 Test Method

20、s for Characterizing Duplex Grain SizesE 1382 Test Methods for Determining Average Grain SizeUsing Semiautomatic and Automatic Image 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 Termin

21、ology E7.3.2 Definitions of Terms Specific to This Standard:3.2.1 ASTM grain size numberthe ASTM grain sizenumber, G, was originally 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

22、grainthat area within the confines of the original(primary) boundary observed on the two-dimensional plane-of-polish or that volume 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 struc

23、ture on either side of a twin boundary belongs to thegrain.3.2.3 grain boundary intersection countdetermination ofthe number of times 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 o

24、f the number oftimes a test line cuts through individual grains on the plane ofpolish (tangent hits are considered as one half an interception;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

25、intersection points on a test linesegment that crosses the grain at any location due to randomplacement of the test line.3.3 Symbols: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 indexfo

26、r a longitudinally oriented plane.d= mean planar grain diameter (Plate III).D= mean spatial (volumetric) grain diameter.f = Jeffries 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 (cons

27、tituent)microstructure.,= mean lineal intercept length on a longitu-dinally oriented surface for a non-equiaxed grain structure.,t= 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 n

28、on-equiaxed grainstructure.,0= base intercept length of 32.00 mm fordefining the relationship between G and ,(and NL) for macroscopically 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.

29、n = number of fields measured.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 standards Document Summary page onthe ASTM website.E 112 96 (2004)e22Na= number of

30、 a grains intercepted by the testline in a two phase (constituent) micro-structure.NA= number of grains per mm2at 1X.NAa= number of a grains per mm2at 1X in atwo phase (constituent) microstructure.NAE= number of grains per inch2at 100X.NA,= NAon a longitudinally oriented surface fora non-equiaxed gr

31、ain structure.NAt= NAon a transversely oriented surface for anon-equiaxed grain structure.NAp= NAon a planar oriented surface for anon-equiaxed grain structure.Ni= number of intercepts with a test line.NInside= number of grains completely within a testcircle.NIntercepted= number of grains intercepte

32、d by the testcircle.NL= number of intercepts per unit length oftest line.NL,= NLon a longitudinally oriented surface fora non-equiaxed grain structure.NLt= NLon a transversely oriented surface for anon-equiaxed grain structure.NLp= NLon a planar oriented surface for anon-equiaxed grain structure.Pi=

33、 number of grain boundary intersectionswith a test line.PL= number of grain boundary intersectionsper unit length of test line.PL,= PLon a longitudinally oriented surface fora non-equiaxed grain structure.PLt= PLon a transversely oriented surface for anon-equiaxed grain structure.PLp= PLon a planar

34、oriented surface for anon-equiaxed grain structure.Q = correction factor for comparison chartratings using a non-standard magnifica-tion for microscopically determined grainsizes.Qm= correction factor for comparison chartratings using a non-standard magnifica-tion for macroscopically determined grai

35、nsizes.s = standard deviation.SV= grain boundary surface area to volumeratio for a single phase structure.SVa= grain boundary surface area to volumeratio for a two phase (constituent) struc-ture.t = students t multiplier for determination ofthe confidence interval.VVa= volume fraction of the a phase

36、 in a twophase (constituent) microstructure.95 % CI = 95 % confidence interval.% RA = percent relative accuracy.4. Significance and Use4.1 These test methods cover procedures for estimating andrules for expressing the average grain size of all metalsconsisting entirely, or principally, of a single p

37、hase. The testmethods may also be used for any structures having appear-ances similar to those of the metallic structures shown in thecomparison charts. The three basic procedures for grain sizeestimation are:4.1.1 Comparison ProcedureThe comparison proceduredoes not require counting of either grain

38、s, intercepts, orintersections but, as the name suggests, involves comparison ofthe grain structure to a series of graded images, either in theform 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 g

39、rain size is somewhat coarser(12 to 1 G number lower) than it actually is (see X1.3.5).Repeatability and reproducibility of comparison chart ratingsare generally 61 grain size number.4.1.2 Planimetric ProcedureThe planimetric method in-volves an actual count of the number of grains within a knownare

40、a. 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 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 an

41、d reproducibility are less than 60.5 grain sizeunits. An accurate count does require marking off of the grainsas they are counted.4.1.3 Intercept ProcedureThe intercept method involvesan actual count of the number of grains intercepted by a testline or the number of grain boundary intersections with

42、 a testline, per unit length of test line, used to calculate the meanlineal intercept length, ,. ,is used to determine the ASTMgrain size number, 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 b

43、e attained witha reasonable amount of effort. Results are free of bias;repeatability and reproducibility are less than 60.5 grain sizeunits. Because an accurate count can be made without need ofmarking off intercepts or intersections, the intercept method isfaster than the planimetric method for the

44、 same level ofprecision.4.2 For specimens consisting of equiaxed grains, themethod of comparing the specimen with a standard chart ismost convenient and is sufficiently accurate for most commer-cial purposes. For higher degrees of accuracy in determiningaverage grain size, the intercept or planimetr

45、ic procedures maybe used. The intercept procedure is particularly useful forstructures consisting of elongated grains.4.3 In case of dispute, 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 mate

46、rial. Partially recrystallizedwrought alloys and lightly to moderately cold-worked materialmay be considered as consisting of non-equiaxed grains, if agrain size measurement is necessary.4.5 Individual grain measurements should not be madebased on the standard comparison charts. These charts werecon

47、structed to reflect the typical log-normal distribution ofgrain sizes that result when a plane is passed through aE 112 96 (2004)e23three-dimensional array of grains. Because they show a distri-bution of grain dimensions, ranging from very small to verylarge, depending on the relationship of the pla

48、nar section andthe three-dimensional array of grains, the charts are notapplicable to measurement of individual grains.5. Generalities of Application5.1 It is important, in using these test methods, to recognizethat the estimation of average grain size is not a precisemeasurement. A metal structure

49、is an aggregate of three-dimensional crystals of varying sizes and shapes. Even if allthese crystals were identical in size and shape, the grain crosssections, 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 te