1、Designation: E112 10E112 12Standard 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 par
2、entheses 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 metall
3、ic materials 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
4、 used if 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
5、 test methods cover the measurement of average grain size and include the comparison procedure, the planimetric (orJeffries) procedure, and the intercept procedures. These test methods may also be applied to nonmetallic materials with structureshaving appearances similar to those of the metallic str
6、uctures shown in the comparison charts. These test methods apply chieflyto single phase grain structures but they can be applied to determine the average size of a particular type of grain structure in amultiphase or multiconstituent specimen.1.2 These test methods are used to determine the average
7、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 tocharacterize the nature of these distributions. Characterization of grain size in specimens with duplex gra
8、in size distributions isdescribed in Test Methods E1181. Measurement of individual, very coarse grains in a fine grained matrix is described in TestMethods E930.1.3 These test methods deal only with determination of planar grain size, that is, characterization of the two-dimensional grainsections re
9、vealed by the sectioning plane. Determination of spatial grain size, that is, measurement of the size of thethree-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 grade
10、d chart images for thecomparison method or simple templates for the manual counting methods. Utilization of semi-automatic digitizing tablets orautomatic image analyzers to measure grain size is described in Test Methods E1382.1.5 These test methods deal only with the recommended test methods and no
11、thing in them should be construed as defining orestablishing 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, arein parentheses and may be approximate.1.7 T
12、his standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.1.8 The paragraphs app
13、ear in the following order:Section NumberScope 11 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 Nov. 1, 2010Nov. 15, 2012. Published December 2010January 2013. Origi
14、nally approved in 1955. Last previous edition approved 20042010 asE112 96E112 10.(2004) 2. DOI: 10.1520/E0112-10.10.1520/E0112-12.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. B
15、ecauseit 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 versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 10
16、0 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1Referenced Documents 2Terminology 3Significance and Use 4Generalities of Application 5Sampling 6Test Specimens 7Calibration 8Preparation of Photomicrographs 9Comparison Procedure 10Planimetric (Jeffries) Procedure 11Ge
17、neral Intercept Procedures 12Heyn Linear Intercept Procedure 13Circular Intercept Procedures 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 18P
18、recision 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 AnnexA3Fracture Grain Size Method AnnexA4Requirements for Wrought Copper and Copper-Base Alloys A
19、nnexA5Application to Special Situations AnnexA6Appendixes:Results of Interlaboratory Grain Size Determinations AppendixX1Referenced Adjuncts AppendixX22. Referenced Documents2.1 ASTM Standards:2E3 Guide for Preparation of Metallographic SpecimensE7 Terminology Relating to MetallographyE407 Practice
20、for Microetching Metals and AlloysE562 Test Method for Determining Volume Fraction by Systematic Manual Point CountE691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test MethodE883 Guide for ReflectedLight PhotomicrographyE930 Test Methods for Estimating the Large
21、st Grain Observed in a Metallographic Section (ALA Grain Size)E1181 Test Methods for Characterizing Duplex Grain SizesE1382 Test Methods for Determining Average Grain Size Using Semiautomatic and Automatic Image Analysis2.2 ASTM Adjuncts:2.2.1 For a complete adjunct list, see Appendix X23. Terminolo
22、gy3.1 DefinitionsFor definitions of terms used in these test methods, see Terminology E7.3.2 Definitions of Terms Specific to This Standard:3.2.1 ASTM grain size numberthe ASTM grain size number, G, was originally defined as:NAE 52G21 (1)where NAE is the number of grains per square inch at 100X magn
23、ification. 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-polishor that volume enclosed by the original (primary) boundary in the three-dimensional object. In mate
24、rials containing twinboundaries, the twin boundaries are ignored, that is, the structure on either side of a twin boundary belongs to the grain.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvo
25、lume information, refer to the standards Document Summary page on the ASTM website.E112 1223.2.3 grain boundary intersection countdetermination of the number of times a test line cuts across, or is tangent to, grainboundaries (triple point intersections are considered as 1-12 intersections).3.2.4 gr
26、ain intercept countdetermination of the number of times 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
27、two opposed, adjacent grain boundary intersection points on a test line segmentthat crosses the grain at any location due to random placement of the test line.3.3 Symbols: = matrix grains in a two phase (constituent) microstructure.A = test area.A = mean grain cross sectional area.AI = grain elongat
28、ion ratio or anisotropy index for 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. = mean lineal intercept length of the m
29、atrix phase in a two phase (constituent) microstructure. = mean lineal intercept length on a longitudinally oriented surface for a non-equiaxed grain structure.t = mean lineal intercept length on a transversely oriented surface for a non-equiaxed grain structure.p = mean lineal intercept length on a
30、 planar oriented surface for a non-equiaxed grain structure.0 = base intercept length of 32.00 mm for defining the relationship between G and (and NL) for macroscopically ormicroscopically determined grain size by the intercept method.L = length of a test line.M = magnification used.Mb = magnificati
31、on used by a chart picture series.n = number of fields measured.N = number of grains intercepted by the test line in a two phase (constituent) microstructure.NA = number of grains per mm2 at 1X.NA = number of grains per mm2 at 1X in a two phase (constituent) microstructure.NAE = number of grains per
32、 inch2 at 100X.NA = NA on a longitudinally oriented surface for a non-equiaxed grain structure.NAt = NA on a transversely oriented surface for a non-equiaxed grain structure.NAp = NA on a planar oriented surface for a non-equiaxed grain structure.NI = number of intercepts with a test line.NInside =
33、number of grains completely within a test circle.N Intercepted = number of grains intercepted by the test circle.NL = number of intercepts per unit length of test line.NL = NL on a longitudinally oriented surface for a non-equiaxed grain structure.NLt = NL on a transversely oriented surface for a no
34、n-equiaxed grain structure.NLp = NL on a planar oriented surface for a non-equiaxed grain structure.PI = number of grain boundary intersections with a test line.PL = number of grain boundary intersections per unit length of test line.PL = PL on a longitudinally oriented surface for a non-equiaxed gr
35、ain structure.PLt = PL on a transversely oriented surface for a non-equiaxed grain structure.PLp = PL on a planar oriented surface for a non-equiaxed grain structure.Q = correction factor for comparison chart ratings using a non-standard magnification for microscopically determinedgrain sizes.Qm = c
36、orrection factor for comparison chart ratings using a non-standard magnification for macroscopically determinedgrain sizes.s = standard deviation.SV = grain boundary surface area to volume ratio for a single phase structure.SV = grain boundary surface area to volume ratio for a two phase (constituen
37、t) structure.t = students t multiplier for determination of the confidence interval.VV = volume fraction of the phase in a two phase (constituent) microstructure.95 %CI = 95 % confidence interval.%RA = percent relative accuracy.E112 1234. Significance and Use4.1 These test methods cover procedures f
38、or estimating and rules for expressing the average grain size of all metals consistingentirely, or principally, of a single phase. The test methods may also be used for any structures having appearances similar to thoseof the metallic structures shown in the comparison charts. The three basic proced
39、ures for grain size estimation are:4.1.1 Comparison ProcedureThe comparison procedure does not require counting of either grains, intercepts, or intersectionsbut, as the name suggests, involves comparison of the grain structure to a series of graded images, either in the form of a wall chart,clear p
40、lastic overlays, or an eyepiece reticle. There appears to be a general bias in that comparison grain size ratings claim thatthe grain size is somewhat coarser (12 to 1 G number lower) than it actually is (see X1.3.5). Repeatability and reproducibility ofcomparison chart ratings are generally 61 grai
41、n size number.4.1.2 Planimetric ProcedureThe planimetric method involves an actual count of the number of grains within a known area.The number of grains per unit area, NA , is used to determine the ASTM grain size number, G. The precision of the method is afunction of the number of grains counted.A
42、precision of 60.25 grain size units can be attained with a reasonable amount of effort.Results are free of bias and repeatability and reproducibility are less than 60.5 grain size units. An accurate count does requiremarking off of the grains as they are counted.4.1.3 Intercept ProcedureThe intercep
43、t method involves an actual count of the number of grains intercepted by a test line orthe number of grain boundary intersections with a test line, per unit length of test line, used to calculate the mean lineal interceptlength, . is used to determine the ASTM grain size number, G. The precision of
44、the method is a function of the number ofintercepts or intersections counted. A precision of better than 60.25 grain size units can be attained with a reasonable amount ofeffort. Results are free of bias; repeatability and reproducibility are less than 60.5 grain size units. Because an accurate coun
45、t canbe made without need of marking off intercepts or intersections, the intercept method is faster than the planimetric method for thesame level of precision.4.2 For specimens consisting of equiaxed grains, the method of comparing the specimen with a standard chart is mostconvenient and is suffici
46、ently accurate for most commercial purposes. For higher degrees of accuracy in determining average grainsize, the intercept or planimetric procedures may be used. The intercept procedure is particularly useful for structures consistingof elongated grains.4.3 In case of dispute, the intercept procedu
47、re shall be the referee procedure in all cases.4.4 No attempt should be made to estimate the average grain size of heavily cold-worked material. Partially recrystallizedwrought alloys and lightly to moderately cold-worked material may be considered as consisting of non-equiaxed grains, if a grainsiz
48、e measurement is necessary.4.5 Individual grain measurements should not be made based on the standard comparison charts. These charts were constructedto reflect the typical log-normal distribution of grain sizes that result when a plane is passed through a three-dimensional array ofgrains. Because t
49、hey show a distribution of grain dimensions, ranging from very small to very large, depending on the relationshipof the planar section and the three-dimensional array of grains, the charts are not applicable to measurement of individual grains.5. Generalities of Application5.1 It is important, in using these test methods, to recognize that the estimation of average grain size is not a precisemeasurement.Ametal structure is an aggregate of three-dimensional crystals of varying sizes and shapes. Even if all these crystalswere
