A quasi in-situ EBSD study of the nucleation and growth of Goss grains during primary and secondary recrystallization of a strip-cast Fe-6.5 wt% Si alloy

Abstract

The nucleation and growth of Goss grains during primary and secondary recrystallization of a strip-cast grain-oriented Fe-6.5 wt% Si alloy were investigated using a quasi in-situ electron backscatter diffraction (EBSD) technique. During primary recrystallization at 700 °C, the Goss was found to nucleate from two locations in the deformed<111>//ND (normal direction) grains: in the shear bands and at the grain boundaries. However, only those nucleated from the shear bands tended to survive during the subsequent grain growth. Even the survived Goss grains would not develop as abnormal Goss grains during secondary recrystallization. Abnormally growing Goss grains were formed at the surfaces when the primary recrystallization temperature was 850 °C, which grew into the center and consumed the entire thickness during secondary recrystallization. The abnormal growth of the Goss grains was attributed to the large fraction of 20–45° grain boundaries at the growing front, which essentially did not change during secondary recrystallization. Using a classical grain growth model, the migration velocities of Goss grains during abnormal growth were calculated, which were compared to the experimental migration velocities obtained from the quasi in-situ EBSD data. It was shown that the model could roughly predict the abnormal growth of the Goss grains during secondary recrystallization.