ASTM E1382 Determining Average Grain Size Using Semiautomatic and Automatic Image Analysis

Scope:

ASTM E1382 test method covers the 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, uniform or duplex grain size distribution. It determines their applications and specifications. The method proceeds with the quality check, heat treatment, and the testing of the chemical composition of materials.  The results obtained from this method help in quality control, research, and performance evaluation of grains.  

Procedure:

For ASTM E1382 testing, the mean grain size depends upon the number of grains per unit area, the length of grain boundaries, and grain intercept lengths. In order to ensure statistical precision, multiple measurements are taken within a microscopic field. Grain intercept lengths or areas are distributed by measuring intercept lengths or areas for a large number of grains and arranging the findings in a histogram pattern; that is, frequency of occurrence vs. class limit ranges. To acquire an appropriate description of the distribution, a large number of measurements across various domains are required.

Video 01: Grain Number Analysis

Specimen Size:

Specimen size should be as per the requirements. In this ASTM E1382 test, the specimen with a minimum polished surface area of 160 mm ² (0.25 in. ²) is adequate.

Data:

Calculate the standard deviation, s, of the NAi (the number of grains per unit area) measurements. The mean grain area, A ̄, can be determined by applying the formula.

Conclusion:

The ASTM E1382 test method is specifically important for the quality assurance and durability check of gains. The grain size and mean length are determined. The top service provider in this regard is the Infinita Lab which ensures efficient and reliable testing.