1 Scope
1.1 This standard specifies the representation and determination methods for average grain size of metallic structure, including comparison procedure, planimetric procedure and intercept procedure; these methods are applicable to single-phase structure, but they, with specific requirements, may also be applied to determine the average size of a particular type of grain in a multi-phase or multi-constituent specimen. These methods may also be applied to nonmetallic materials with structures having appearances similar to those of the metallic structures shown in the comparison charts.
1.2 This standard is applied to determine the average grain size of specimens with a unimodal distribution (similar to lognormal distribution) of grain areas, diameters or intercept lengths, and is not applicable to the grain size in bimodal distribution. Characterization of duplex grain size is described in GB/T 24177. Test methods for determining individual very coarse grains in a fine grained matrix are described in YB/T 4290.
1.3 This standard deals only with determination of planar grain size. Determination of spatial grain size, that is, measurement of the size of the three-dimensional grains, is beyond the scope of this standard.
1.4 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 of purpose of the materials tested.
2 Normative References
The following documents for the application of this document are essential. Any dated reference, just dated edition applies to this document. For undated references, the latest edition (including any amendments) applies to this document.
GB/T 4335 Determination of Ferrite Grain Size for Cold Rolled Low Carbon Steel Sheets
GB/T 13298 Inspection Methods of Microstructure for Metals
GB/T 24177 Standard Test Methods for Characterizing Duplex Grain Sizes
GB/T 30067 Standard Terminology Relating to Metallography
YB/T 4290 Test Methods for Estimating the Largest Grain Observed in a Metallographic Section (ALA Grain Size)
3 Terms and Definitions
For the purposes of this document, the terms and definitions defined in GB/T 30067 and the following apply.
