Effect of hot band grain size on the anisotropy of warm rolled low carbon steels

In warm rolled steels, the intensity of the < 111 >//ND annealing texture, which favours formability, has been related to the formation of shear bands during rolling. Coarse hot band grain sizes (HBGS's) facilitate flow localization, the mechanism associated with the formation of shear bands. In this work, the effect of grain size after hot rolling was studied in a low carbon steel containing small additions of Cr and Mn. The formation of shear bands and their subsequent influence on the normal anisotropy r(m) and planar anisotropy Delta r in the annealed steels were of particular interest. Two HBGS's (18 and 30 mu m) were employed and the specimens were warm rolled to reductions of 65 and 80% at various temperatures between 640 and 700 degrees C. The results show that the frequency of shear banding is slightly lower for the smaller grain size. The normal anisotropy was not affected by the HBGS; by contrast, much lower Delta r values were associated with the finer grained steel.