2.The mechanism of abnormal growth of Goss oriented grainsduring secondary recrystallization of oriented electrical steels

Abstract:

The theory of secondary recrystallization of grain oriented electrical steels is of great significance for guiding the adjustmentof production processes and ensuring product quality． During the secondary recrystallization process，the dispersively distributed inhibi-tor particles strongly hinder grain boundary migration and grain growth． Therefore，the existing secondary recrystallization theory，whichonly focuses on the initial migration behaviors of grain boundaries，not only fails to clarify the mechanism of secondary recrystallization，but also cannot explain why some smaller Goss grains can finally，as a frequent behavior，engulf all other grains． The investigation sug-gests that the significant molar volume effect generated by the precipitation of inhibitor particles within the ferrite matrix strongly inhibitsthe coarsening of the particles in the central layer of steel sheets at high temperatures，but there is still a chance for coarsening of parti-cles in the surface layer． Therefore，the surface grains can grow before the growth of central layer grains． The prominent elastic anisot-ropy of ferrite at high temperatures causes the grain boundaries of large-sized non-Goss grains on the surface layer to only slowly migratetowards Goss grains，while the grain boundaries of surface Goss grains can quickly migrate towards adjacent small-sized non-Goss grainsgradually accumulating an absolute advantage in size，devouring all other grains and finally forming a strong Goss texture．

Keywords: grain oriented electrical steel; Goss grains; abnormal growth; texture