Factors affecting the final grain size of decarburized lamination steels

Abstract

A study was made of the effects of carbon content, strain, initial grain size, carbide morphology, annealing time, and temperature on the final grain size produced after the decarburization anneal. The results show that columnar grains form only in higher carbon (0.05/0.06 Pct C) steels with low initial grain sizes (<20 µm) when decarburized at 1450 °F (788 °C). Equiaxed grains, however, are obtained in low carbon (0.02/0.03 Pct C) lamination steels for all processing conditions. It was found that the formation of both equiaxed and columnar final grain size (GS f ) was dependent upon percent strain (e), initial grain size (GS i ), and carbide distribution (D c ) according to the following regression equations (all grain size measurements in µm):G5 f (columnar grain) = 204 + 0.9GSi - 12.3e + 37.8D C logGS f (equiaxed grain) = 2.151 + 0.022GSi - 0.038e - 0.0005GS i · e- 0.0002(GS i )2 + 0.079D c