Standard Test Methods for Estimating the Largest Grain Observed in a Metallographic Section (ALA Grain Size)

Importancia y uso:

4.1 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.

4.2 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.

4.3 These methods shall not be used for the determination of average grain size, which is treated in Test Methods E112. 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.

4.4 These methods may be applied in the characterization of duplex grain sizes, as instructed in the procedures for Test Methods E1181.

Subcomité:

E04.08

Referida por:

F0799-19, E1181-02R23, E1382-97R23, E0112-24, E0112-24, E0112-24

Volúmen:

03.01

Número ICS:

19.120 (Particle size analysis. Sieving)

Palabras clave:

ALA grain; caliper diameter; comparison procedure; ellipse measurement; grain size; largest grain; measuring procedure; metallography; microstructure; outlier grain; point-count procedure;