1、Designation: E1382 97 (Reapproved 2015)Standard Test Methods forDetermining Average Grain Size Using Semiautomatic andAutomatic Image Analysis1This standard is issued under the fixed designation E1382; the number immediately following the designation indicates the year oforiginal adoption or, in the
2、 case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () 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 of
3、 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 util
4、ized 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 automa
5、tic 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 These t
6、est 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 tested.1
7、.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 sections
8、 appear in the following order:Section SectionScope 1Referenced Documents 2Terminology 3Definitions 3.1Definitions of Terms Specific to This Standard 3.2Symbols 3.3Summary of Test Method 4Significance and Use 5Interferences 6Apparatus 7Sampling 8Test Specimens 9Specimen Preparation 10Calibration 11P
9、rocedure: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 Chord (Intercept) Le
10、ngth/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 StructureSpecimensAnne
11、xA1Examples of Proper and Improper Grain BoundaryDelineationAnnexA21These test methods are under the jurisdiction of ASTM Committee E04 onMetallography and are the direct responsibility of Subcommittee E04.14 onQuantitative Metallography.Current edition approved Oct. 1, 2015. Published February 2016
12、. Originallyapproved in 1991. Last previous edition approved in 2010 as E1382 97(2010).DOI: 10.1520/E1382-97R15.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States12. Referenced Documents2.1 ASTM Standards:2E3 Guide for Preparation of Met
13、allographic SpecimensE7 Terminology Relating to MetallographyE112 Test Methods for Determining Average Grain SizeE407 Practice for Microetching Metals and AlloysE562 Test Method for Determining Volume Fraction bySystematic Manual Point CountE883 Guide for ReflectedLight PhotomicrographyE930 Test Met
14、hods for Estimating the Largest Grain Ob-served in a Metallographic Section (ALA Grain Size)E1181 Test Methods for Characterizing Duplex Grain SizesE1245 Practice for Determining the Inclusion or Second-Phase Constituent Content of Metals by Automatic ImageAnalysis3. Terminology3.1 DefinitionsFor de
15、finitions of terms used in these testmethods, (feature-specific measurement, 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
16、grain boundary intersection points on astraight test line segment that crosses 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 considere
17、d as one half an interception).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 as112 intersections).3.2.4 image processinga generic term covering a varietyof video techniq
18、ues that are used to enhance or modifycontrast, find and enhance edges, clean images, and so forth,prior to measurement.3.2.5 skeletonizationan iterative image amendment proce-dure in which pixels are removed from the periphery of thegrain boundaries (“thinning”), or other features, unless removalwo
19、uld produce a loss of connectivity, until each pixel has nomore than two nearest neighbors (except at a junction); this isfollowed by extension of line ends until they meet other lineends, to connect missing or poorly delineated grain boundaries.3.2.6 watershed segmentationan iterative image amend-m
20、ent procedure in which each grain, or other features, iseroded to a single pixel, without loosing that pixel (ultimateerosion”); 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: = the phase of int
21、erest for grain size mea-surement in a two-phase (constituent) microstructure.A= average area of grains in a two-phase (constituent)microstructure.AA= area fraction of 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
22、the ithfield.Ai= mean grain area for the ithfield.Amax= area of 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.l= mean lineal intercept length of the phase in atwo-phase microstructure for n field
23、s measured.li= mean lineal intercept length of the phase in 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 int
24、ercept length for the ithfield.Li= length of grain boundaries 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 = num
25、ber of grains measured or the number of grainintercepts counted.NA= mean number of grains per unit test area for nfieldsmeasured.NAi= number of grains per unit area for the ithfield.N= mean number of grains in a two-phase microstructureintercepted by the test lines or scan lines.Ni= number of grains
26、 in a two-phase microstructureintercepted by the test 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
27、 for n fields measured.NLi= number of grains intercepted 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 f
28、or nfields measured.PLi= number of grain boundary intersections per unit lengthof test lines or scan lines for the ithfield.PP= point fraction of the 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
29、.Xi= any individual measurement.95 % CI = 95 % confidence interval.% RA = percent relative accuracy.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 Do
30、cument Summary page onthe ASTM website.E1382 97 (2015)24. 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 intersectio
31、ns 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 additionalfields to obtain an adequate number of measurements toachieve the desired degree of statistical pre
32、cision.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 several fields are
33、 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 with equiaxed or defo
34、rmed 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 associated withmanual me
35、asurements, 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 specimen orspecimens
36、, 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 boundaries, and so fort
37、h),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 process variations,
38、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 lead to measurement err
39、ors, 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-centered cubic metals a
40、nd 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 that do not delineate
41、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 field evaluatedusing
42、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 etchedspecimens, must be u
43、sed with caution as false boundaries maybe created 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 detected as grain boundarie
44、s 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 revealed at all. Exces-
45、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 automatic image analysis a
46、ndalso measurements made with a digitizing tablet.6.7 Detection of proeutectoid 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 interlamellar spacingis c
47、oarse. 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 themeasurement results.6.9 If photo
48、graphic 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 usingautomatic image analysis.6.1
49、1 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.E1382 97 (2015)36.12 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 fo
