1、Designation: E 1382 97 (Reapproved 2004)Standard Test Methods forDetermining Average Grain Size Using Semiautomatic andAutomatic Image Analysis1This standard is issued under the fixed designation E 1382; the number immediately following the designation indicates the year oforiginal adoption or, in t
2、he case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.INTRODUCTIONThese test methods may be used to determine the mean grain size, or the distribution
3、 of grainintercept lengths or areas, in metallic and nonmetallic polycrystalline materials. The test methods maybe applied to specimens with equiaxed or elongated grain structures with either uniform or duplexgrain size distributions. Either semiautomatic or automatic image analysis devices may be u
4、tilized toperform the measurements.1. Scope1.1 These test methods are used to determine grain sizefrom measurements of grain intercept lengths, intercept counts,intersection counts, grain boundary length, and grain areas.1.2 These measurements are made with a semiautomaticdigitizing tablet or by aut
5、omatic image analysis using an imageof the grain structure produced by a microscope.1.3 These test methods are applicable to any type of grainstructure or grain size distribution as long as the grainboundaries can be clearly delineated by etching and subsequentimage processing, if necessary.1.4 Thes
6、e test methods are applicable to measurement ofother grain-like microstructures, such as cell structures.1.5 This standard deals only with the recommended testmethods and nothing in it should be construed as defining orestablishing limits of acceptability or fitness for purpose of thematerials teste
7、d.1.6 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 appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.1.7 The secti
8、ons appear in the following order:Section Sec-tionScope 1Referenced Documents 2Terminology 3Definitions 3.1Definitions of Terms Specific to This Standard 3.2Symbols 3.3Section Sec-tionSummary of Test Method 4Significance and Use 5Interferences 6Apparatus 7Sampling 8Test Specimens 9Specimen Preparati
9、on 10Calibration 11Procedure:Semiautomatic Digitizing Tablet 12Intercept Lengths 12.3Intercept and Intersection Counts 12.4Grain Counts 12.5Grain Areas 12.6ALA Grain Size 12.6.1Two-Phase Grain Structures 12.7Procedure:Automatic Image Analysis 13Grain Boundary Length 13.5Intersection Counts 13.6Mean
10、Chord (Intercept) Length/Field 13.7.2Individual Chord (Intercept) Lengths 13.7.4Grain Counts 13.8Mean Grain Area/Field 13.9Individual Grain Areas 13.9.4ALA Grain Size 13.9.8Two-Phase Grain Structures 13.10Calculation of Results 14Test Report 15Precision and Bias 16Grain Size of Non-Equiaxed Grain St
11、ructure Speci-mensAnnexA1Examples of Proper and Improper Grain Boundary De-lineationAnnexA22. Referenced Documents2.1 ASTM Standards:2E3 Practice for Preparation of Metallographic Specimens1These test methods are under the jurisdiction of ASTM Committee E04 onMetallography and are the direct respons
12、ibility of Subcommittee E04.08 on GrainSize.Current edition approved Nov. 1, 2004. Published November 2004. Originallyapproved in 1991. Last previous edition approved in 1997 as E 1382 97.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at service
13、astm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.E7 Terminology Relating to MetallographyE112 Test Methods
14、for Determining Average Grain SizeE 407 Practice for Microetching Metals and AlloysE 562 Practice for Determining Volume Fraction by Sys-tematic Manual Point CountE 883 Guide for Reflected Light PhotomicrographyE 930 Test Methods for Estimating the Largest Grain Ob-served in a Metallographic Section
15、 (ALA Grain Size)E 1181 Test Methods for Characterizing Duplex Grain SizesE 1245 Practice for Determining the Inclusion or Second-Phase Constituent Content of Metals by Automatic ImageAnalysis3. Terminology3.1 DefinitionsFor definitions of terms used in these testmethods, (feature-specific measureme
16、nt, field measurement,flicker method, grain size, gray level, and threshold setting),see Terminology E7.3.2 Definitions of Terms Specific to This Standard:3.2.1 chord (intercept) lengththe distance between twoopposed, adjacent grain boundary intersection points on astraight test line segment that cr
17、osses the grain at any locationdue to random placement of the test line.3.2.2 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 interception).3.2.3 grain boundary intersection countdet
18、ermination ofthe number of times a test line cuts across, or is tangent to,grain boundaries (triple point intersections are considered as112 intersections).3.2.4 image processinga generic term covering a varietyof video techniques that are used to enhance or modifycontrast, find and enhance edges, c
19、lean images, and so forth,prior to measurement.3.2.5 skeletonizationan iterative image amendment pro-cedure in which pixels are removed from the periphery of thegrain boundaries (88thinning”), or other features, unless re-moval would produce a loss of connectivity, until each pixelhas no more than t
20、wo nearest neighbors (except at a junction);this is followed by extension of line ends until they meet otherline ends, to connect missing or poorly delineated grainboundaries.3.2.6 watershed segmentationan iterative image amend-ment procedure in which each grain, or other features, iseroded to a sin
21、gle pixel, without loosing that pixel (88ultimateerosion”); this is followed by dilation without touching torebuild the grain structure with a very thin line (grain bound-aries) separating each grain.3.3 Symbols:a = the phase of interest for grain size measurement in atwo-phase (constituent) microst
22、ructure.Aa= average area of a grains in a two-phase (constituent)microstructure.AAa= area fraction of a grains in a two-phase microstruc-ture.Agi= total area of grains in the ithfield.Ai= true area of the ithgrain; or, the test area of the ithfield.Ai= mean grain area for the ithfield.Amax= area of
23、the largest observed grain.Ati= true test area for the ithfield.d = diameter of test circle.G = ASTM grain size number.l= mean lineal intercept length.la= mean lineal intercept length of the a phase in atwo-phase microstructure for n fields measured.lai= mean lineal intercept length of the a phase i
24、n atwo-phase microstructure for the ithfield.L = test line or scan line length.LA= mean grain boundary length per unit test area.LAi= grain boundary length per unit test area for the ithfield.li= intercept length for the ithgrain.li= mean intercept length for the ithfield.Li= length of grain boundar
25、ies in the ithfield.Lti= true test line or scan line length for the ithfield.Lv= length of grain edges per unit volume.M = magnification.n = number of fields measured or the number of gridplacements (or the number of any measurements).N = number of grains measured or the number of grainintercepts co
26、unted.NA= mean number of grains per unit test area for nfieldsmeasured.NAi= number of grains per unit area for the ithfield.Na= mean number of a grains in a two-phase microstruc-ture intercepted by the test lines or scan lines.Nai= number of a grains in a two-phase microstructureintercepted by the t
27、est lines or scan lines for the ithfield.Ni= number of grains intercepted by the test lines or scanlines for the ithfield; or, the number of grains counted in the ithfield.NL= mean number of grain intercepts per unit length of testlines or scan lines for n fields measured.NLi= number of grains inter
28、cepted per unit length of testlines or scan lines for the ithfield.Pi= number of grain boundaries intersected by the test linesor scan lines for the ithfield.PL= mean number of grain boundary intersections per unitlength of test lines or scan lines for nfields measured.PLi= number of grain boundary
29、intersections per unit lengthof test lines or scan lines for the ithfield.PPa= point fraction of the a grains in a two-phase micro-structure.sv= grain boundary surface area per unit volume.s = standard deviation = (1/(n 1)( (XiX)2.X= any mean value = ( Xi/n.Xi= any individual measurement.95 % CI = 9
30、5 % confidence interval.% RA = percent relative accuracy.4. Summary of Test Methods4.1 Determination of the mean grain size is based onmeasurement of the number of grains per unit area, the lengthof grain boundaries in unit area, grain areas, the number ofgrain intercepts or grain boundary intersect
31、ions per unit length,or grain intercept lengths. These measurements are made for alarge number of grains, or all of the grains in a given area,within a microscopical field and then repeated on additionalE 1382 97 (2004)2fields to obtain an adequate number of measurements toachieve the desired degree
32、 of statistical precision.4.2 The distribution of grain intercept lengths or areas isaccomplished by measuring intercept lengths or areas for alarge number of grains and grouping the results in histogramfashion; i.e., frequency of occurrence vs. class limit ranges. Alarge number of measurements over
33、 several fields are requiredto obtain an adequate description of the distribution.5. Significance and Use5.1 These test methods cover procedures for determiningthe mean grain size, and the distribution of grain interceptlengths or grain areas, for polycrystalline metals and nonme-tallic materials wi
34、th equiaxed or deformed grain shapes, withuniform or duplex grain size distributions, and for single phaseor multiphase grain structures.5.2 The measurements are performed using semiautomaticdigitizing tablet image analyzers or automatic image analyzers.These devices relieve much of the tedium assoc
35、iated withmanual measurements, thus permitting collection of a largeramount of data and more extensive sampling which willproduce better statistical definition of the grain size than bymanual methods.5.3 The precision and relative accuracy of the test resultsdepend on the representativeness of the s
36、pecimen or speci-mens, quality of specimen preparation, clarity of the grainboundaries (etch technique and etchant used), the number ofgrains measured or the measurement area, errors in detectinggrain boundaries or grain interiors, errors due to detecting otherfeatures (carbides, inclusions, twin bo
37、undaries, and so forth),the representativeness of the fields measured, and program-ming errors.5.4 Results from these test methods may be used to qualifymaterial for shipment in accordance with guidelines agreedupon between purchaser and manufacturer, to compare differ-ent manufacturing processes or
38、 process variations, or to pro-vide data for structure-property-behavior studies.6. Interferences6.1 Improper polishing techniques that leave excessivelylarge scratches on the surface, or produce excessive deforma-tion or smearing of the microstructure, or produce pull-outsand other defects, will le
39、ad to measurement errors, particularlywhen automatic image analyzers are employed.6.2 Etching techniques or etchants that produce only partialdelineation of the grain boundaries will bias test results andmust be avoided.6.3 Etching techniques or etchants that reveal annealingtwins in certain face-ce
40、ntered cubic metals and alloys usuallyshould be avoided if the grain size is to be measured byautomatic image analyzers. The presence of twin boundariescan be tolerated when semiautomatic digitizing tablets areutilized but measurement errors are more likely to occur.Etching techniques and etchants t
41、hat do not delineate twinboundaries are preferred for these specimens. Discriminationof grain boundaries but not twin boundaries using imageamendment techniques may be possible with some automaticimage analyzers. Such techniques may be employed if theoperator can demonstrate their reliability. Each
42、field evaluatedusing these methods should be carefully examined before (orafter) measurements are made and manually edited, if neces-sary.6.4 Image processing techniques employed to completemissing or incompletely developed grain boundaries, or tocreate grain boundaries in grain-contrast/color etche
43、d speci-mens, must be used with caution as false boundaries may becreated in the former case, and grain boundaries may not beproduced between adjacent grains with similar contrast or colorin the latter case.6.5 Inclusions, carbides, nitrides, and other similar constitu-ents within grains may be dete
44、cted as grain boundaries whenautomatic image analyzers are utilized. These features shouldbe removed from the field before measurements are made.6.6 Orientation-sensitive etchants should be avoided assome boundaries are deeply etched, others are properly etched,while some are barely revealed or not
45、revealed at all. Exces-sively deep etching with such etchants to bring out the fainterboundaries should not be done because deep etching createsexcessive relief (deviation from planar conditions) and willbias certain measurements, particularly grain intercept lengthsand grain areas, performed by aut
46、omatic image analysis andalso measurements made with a digitizing tablet.6.7 Detection of proeutectoid a grains in steels containingferrite and pearlite (and other alloys with similar structures) byautomatic image analyzers can result in detection of ferritewithin the pearlitic constituent when the
47、interlamellar spacingis coarse. Use of high magnifications accentuates this problem.For such structures, use the lowest possible magnification, oruse semiautomatic devices.6.8 Dust, pieces of tissue paper, oil or water stains, or otherforeign debris on the surface to be examined will bias themeasure
48、ment results.6.9 If photographic images are measured using a digitizingtablet, uncertainties in the magnification (particularly whenenlargements are used) will bias the test results.6.10 Vibrations, if present, can blur the image and bias testresults and must be minimized or eliminated when usingaut
49、omatic image analysis.6.11 Dust in the microscope or camera system may producespurious detail in the image that may be detected as a grainboundary, particularly on automatic image analyzers, and willbias the test results. Consequently, the imaging system must bekept clean.6.12 Nonuniform illumination can influence feature detec-tion and thresholding using automatic image analyzers. Prior toanalysis, center the light source (as described in the operatinginstructions for the microscope) and adjust the field andaperture diaphragms for best image clarity. Digi
