Dependence of recrystallization behavior and magnetic properties on grain size prior to cold rolling in high silicon non-oriented electrical steel

The present work aimed to investigate the roles of prior grain size of the hot rolled sheets after normalization on final recrystallization behavior and magnetic properties in 3.1%Si + 0.9%Al non-oriented electrical steel. Bigger prior grain size produced coarser deformed grains and promoted the development of in-grain shear bands, which together resulted in distinct recrystallization behavior. The prior small-grained microstructure caused relatively slow kinetics at the early stage of recrystallization, while fast kinetics was displayed at the later stage due to the growth of new γ(<111>//normal direction (ND))-grains and led to strong γ-fiber recrystallization texture. By contrast, the prior big-grained microstructure gave rise to relatively fast recrystallization kinetics at the early stage due to the diversified nucleation orientation and rapid grain growth in the interior of coarse deformed γ-grains with the help of in-grain shear bands. However, relatively slow kinetics was displayed at the later stage because the coarse deformed λ(<001>//ND)-grains were sluggish to recrystallize. Hence, continuous recrystallization and shear bands induced nucleation contributed to strong λ-fiber texture. Magnetic induction B50 continuously improved as the prior grain size increased, while both the low-frequency core loss P15/50 and the high-frequency core loss P10/400 decreased firstly and then increased with different critical prior grain size.