【国外标准】 Standard Test Methods for Determining Average Grain Size Using Semiautomatic and Automatic Image Analysis

5.1 These test methods cover procedures for determining the mean grain size, and the distribution of grain intercept lengths or grain areas, for polycrystalline metals and nonmetallic materials with equiaxed or deformed grain shapes, with uniform or duplex grain size distributions, and for single phase or multiphase grain structures.5.2 The measurements are performed using semiautomatic digitizing tablet image analyzers or automatic image analyzers. These devices relieve much of the tedium associated with manual measurements, thus permitting collection of a larger amount of data and more extensive sampling which will produce better statistical definition of the grain size than by manual methods.5.3 The precision and relative accuracy of the test results depend on the representativeness of the specimen or specimens, quality of specimen preparation, clarity of the grain boundaries (etch technique and etchant used), the number of grains measured or the measurement area, errors in detecting grain boundaries or grain interiors, errors due to detecting other features (carbides, inclusions, twin boundaries, and so forth), the representativeness of the fields measured, and programming errors.5.4 Results from these test methods may be used to qualify material for shipment in accordance with guidelines agreed upon between purchaser and manufacturer, to compare different manufacturing processes or process variations, or to provide data for structure-property-behavior studies.1.1 These test methods are used to determine grain size from measurements of grain intercept lengths, intercept counts, intersection counts, grain boundary length, and grain areas.1.2 These measurements are made with a semiautomatic digitizing tablet or by automatic image analysis using an image of the grain structure produced by a microscope.1.3 These test methods are applicable to any type of grain structure or grain size distribution as long as the grain boundaries can be clearly delineated by etching and subsequent image processing, if necessary.1.4 These test methods are applicable to measurement of other grain-like microstructures, such as cell structures.1.5 This standard deals only with the recommended test methods and nothing in it should be construed as defining or establishing limits of acceptability or fitness for purpose of the materials tested.1.6 The sections appear in the following order:Section Section  1Referenced Documents  2Terminology  3 Definitions  3.1 Definitions of Terms Specific to This Standard  3.2 Symbols  3.3Summary of Test Method  4  5Interferences  6Apparatus  7Sampling  8Test Specimens  9Specimen Preparation 10Calibration 11Procedure:   Semiautomatic Digitizing Tablet 12 Intercept Lengths 12.3 Intercept and Intersection Counts 12.4 Grain Counts 12.5 Grain Areas 12.6 ALA Grain Size 12.6.1 Two-Phase Grain Structures 12.7Procedure:   Automatic Image Analysis 13 Grain Boundary Length 13.5 Intersection Counts 13.6 Mean Chord (Intercept) Length/Field 13.7.2 Individual Chord (Intercept) Lengths 13.7.4 Grain Counts 13.8 Mean Grain Area/Field 13.9 Individual Grain Areas 13.9.4 ALA Grain Size 13.9.8 Two-Phase Grain Structures 13.10Calculation of Results 14Test Report 15Precision and Bias 16Grain Size of Non-Equiaxed Grain Structure Specimens Annex A1Examples of Proper and Improper Grain Boundary Delineation Annex A21.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.8 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.