1.1 This standard specifies the representation and estimation method of average grain size in metal. These methods also may be applied to nonmetallic materials with structures having appearance similar to those shown in the rating charts in this standard. These methods apply mainly to single phase grain structures but they can be applied to determine the average size of a particular type of grain structure in a multiphase or multiconstituent specimen.
1.2 This standard determines the average grain size of specimens with a unimodal distribution of grain areas, diameters, or intercept lengths. These distributions are approximately log normal. These test methods in this standard doesn’t apply in grain with duplex distribution.
1.3 These test methods deal only with determination of planar grain size, that is, characterization of the two-dimensional grain sections revealed by the sectioning plane. Determination of spatial grain size of specimen, that is, measurement of the size of the three-dimensional grains, is beyond the scope of these test methods.
1.4 This standard is only of recommended test methods, and it should not be construed as defining or establishing limits of acceptability or fitness of the materials tested.
