Effect of Rapid Heating on Columnar Grain Growth in Non-Oriented Electrical steels

The microstructure creation of electrical steels depends on heat treatment conditions. The influence of heating rates in the range of 10 to 25 deg C/s was investigated under laboratory conditions. The rapid heating in fully processed non-oriented electrical steel leads to columnar grain growth by diffusion induced grain boundary migration mechanism (DIBM). It was experimentally shown that temper-rolling process produces a concentrated deformation on the surface. This type of deformation together with strong temperature gradient, as a consequence of rapid heating, present a high driving force for directly abnormal grain growth in semi-processed non-oriented electrical steels.