ASTM Grain Size Number
The ASTM standard E112 was adopted in 1961 for rating grain size. The value of the grain size number, G, is dependent upon the number of grains per square inch, observed on a polished and etched metallographic specimen at a magnification of 100X. As the value of the number of grains per square inch increases, so does the grain size number. The value of C is usually rounded to the nearest one-half value. A circle template can be used for both techniques provided the grain size is equiax. Grains that are tangent to the circle are counted as one-half a grain boundary intercept and grain corner intercepts are counted as 1.5. ASTM grain size numbers are unambiguous and provide an easy measure by which materials can be compared.
D. C. Van Aken, "ASTM Grain Size Number," Industrial Heating, BNP Media, Inc., Jan 1999.
Materials Science and Engineering
Article - Journal
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