Characterization of grain size ASTM International standard methods: http://materials.mcmaster.ca/faculty/malakhov/4L04/ReferenceMaterials/AST M%20standards/ASTM%20E112-10%20Average%20Grain%20Size.pdfASTM International http://materials.mcmaster.ca/faculty/malakhov/4L04/ReferenceMaterials/AST M%20standards/ASTM%20E112-10%20Average%20Grain%20Size.pdf ASTM grain size number, n = (log N/log 2) + 1 where N is the number of grains per square inch at 100X.
{}