Study of potential recrystallization nuclei in the cold-rolled microstructure of an electrical steel by electron backscatter diffraction

Strain induced boundary migration (SIBM) is widely recognized to be the main mechanism corresponding to recrystallization in metals of low or medium amount of deformation. The nucleation process in recrystallization of heavily deformed metals is, however, less understood for key issues such as how the nuclei are formed and where they are located. The evolution of texture from deformation to recrystallization cannot thus be explained well. In this study, an attempt was conducted to identify the potential recrystallization nuclei (PRN) in the cold-rolled microstructure of an electrical steel by electron backscatter diffraction (EBSD). This work demonstrates that the SIBM mechanism can be the main mechanism corresponding to recrystallization nucleation in a heavily deformed steel. The same area in both the cold-rolled and partially recrystallized states was analysed using EBSD to obtain the correlation between the recrystallized grains and the cold-rolled substructures. The deformed grains having high stored energy were first selected, followed by identifying substructures surrounded entirely or partly by high angle boundaries in these heavily deformed grains. The deformation induced grains having low intra-granular misorientation of 2° or less exhibit a very similar orientation distribution to that of the recrystallized grains and are proposed to be the PRN in subsequent recrystallization.