Effect of the Initial Columnar‐Grained Inhomogeneity of Electrical Steels on the Transformation Temperature

Abstract

The effects of various initial structures and heating and cooling rates on the columnar‐grained transformation temperature are studied by a thermal dilatometer and electron backscatter diffraction. The results show that deformation can reduce the thermal hysteresis more effectively than decrease the heating rate, and the phase transformation hysteresis of the deformed sample is the smallest during heating, followed by the columnar‐grained sample with a slow heating rate, whereas the columnar‐grained sample with a fast heating rate has the largest phase transformation hysteresis. Moreover, the dilatational amount changes greatly with cooling rate. The coarse columnar grains can severely restrain dilatation. The smaller dilatational amount is related to the incomplete phase transformation of the columnar grains and also related to the suppression of the dilatational amount of the small grains by the surrounding columnar grains. In contrast, the largest dilatational amount is caused by the relatively sufficient phase transformation. In addition, the changes of the transformation temperature and the dilatational amount are mainly induced by the grain size effect and the inhomogeneity of the structures, but {100} texture can affect the uniformity of grain size.