Measuring the Grain Size of Specimens with Non-Equiaxed Grains

摘要

If a specimen has been cold worked, or it did not recrystallize after hot working, the grains will not be equiaxed and extra care must be taken when assessing the specimen's grain size. Always test a longitudinally oriented plane first to determine if the grains are, or are not, equiaxed. In this work, a low-carbon sheet steel was tested in the as-received condition (reportedly annealed), and after cold reductions in thickness of 12, 30 and 70%. Above 70% reduction, it can be quite difficult to reveal the ferrite grain boundaries well enough to get a precise measurement. Measurements were made on the three principal planes using the Jeffries planimetric method, the Abrams three-circle intercept method and the intercept method using directed parallel test lines. Grain elongation was assessed using the simple anisotropy ratio and the Saltykov degree of orientation method.