Effect of Grain Size Before Cold Rolling on Microstructure, Texture and Magnetic Properties of Ultra-Thin Low-Si Non-oriented Silicon Steel

The present work aims to investigate the effects of prior grain size of hot rolled sheets after normalization on microstructure, texture evolution, recrystallization kinetics, and magnetic properties in 1.6% Si non-oriented silicon steel. With the increase of normalizing temperature, coarse grains will be produced, which directly leads to different recrystallization behaviors. The microstructure with a smaller grain size before cold rolling has a slow driving force at the early recrystallization stage, then at the later recrystallization stage, the grains have relatively fast kinetics by annexing adjacent deformed grains. By contrast, the microstructure with a larger grain size before cold rolling has a faster dynamic force in early recrystallization, and the shear band provides nucleation location and stores energy for recrystallization, while the dynamic force in the later recrystallization is relatively slow. The magnetic induction intensity increases with the increase of grain size before cold rolling, P 1.5/50 , P 1.0/400 and P 1.0/1000 decrease first and then increase. When the grain size before cold rolling is 154.8 μ m, the grain size of the finished sheet is 112.6 μ m, the magnetic induction intensity is 1.738 T, and the optimal iron losses for P 1.5/50 , P 1.0/400 , and P 1.0/1000 were 2.311W/kg, 18.399W/kg and 78.48W/kg, respectively.