An investigation into the cause of inhomogeneous distributions of aluminium nitrides in silicon steels

Two electrical steels containing 0.014 wt.% aluminium and 0.013–0.014 wt.% nitrogen were characterised to determine the operating recrystallisation mechanism following different heat treatment schedules. It was found that the operating recrystallisation mechanism depended on grain orientation with sub-grain coalescence and low-angle boundary movement occurring for {111}〈uvw〉-oriented grains and high-angle boundary movement occurring for {110}〈uvw〉-oriented grains in the narrow deformed bands. In addition, the number density of AlN precipitates (characterised using TEM) was larger in the {111}〈uvw〉-oriented grains compared to the {110}〈uvw〉-oriented grains. The higher number density of precipitates was due to the presence of dislocations remaining after recrystallisation.