Grain Size Measurement
Grain size is normally quantified by a numbering system. Coarse 1-5 and fine 5-8. The number is derived fron the formula N 2n-1 where n is the number of grains per square inch at a magnification of 100 diameters. Grain size has an important effect on physical properties. For service at ordinary temperatures it is generally considered that fine grained steels give a better combination of strength and toughness, whereas coarse grained steels have better machinability.
