ASTM International - ASTM E930-99(2007)
Standard Test Methods for Estimating the Largest Grain Observed in a Metallographic Section (ALA Grain Size)
|Publication Date:||1 October 2007|
|ICS Code (Particle size analysis. Sieving):||19.120|
significance And Use:
The presence of large grains has been correlated with anomalous mechanical behavior in, for example, crack initiation, crack propagation, and fatigue. Thus there is engineering justification for... View More
The presence of large grains has been correlated with anomalous mechanical behavior in, for example, crack initiation, crack propagation, and fatigue. Thus there is engineering justification for reporting the ALA grain size.
These methods shall only be used with the presence of outlier coarse grains, 3 or more ASTM grain size numbers larger than the rest of the microstructure and comprising 5 % or less of the specimen area. A typical example is shown in Annex A1 as Fig. A1.1.
These methods shall not be used for the determination of average grain size, which is treated in Test Methods E 112. Examples of microstructures that do not qualify for ALA treatment are shown in Annex A1 as Fig. A1.2, Fig. A1.3, and Fig. A1.4.
These methods may be applied in the characterization of duplex grain sizes, as instructed in the procedures for Test Methods E 1181.View Less
1.1 These test methods describe simple manual procedures for measuring the size of the largest grain cross-section observed on a metallographically prepared plane section.
1.2 These test methods shall only be valid for microstructures containing outlier coarse grains, where their population is too sparse for grain size determination by Test Methods E 112.
1.3 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.