Influence of grain size and texture prior to warm rolling on microstructure, texture and magnetic properties of Fe-6.5 wt% Si steel

Highlights: • Fe-6.5 wt% Si steel sheets were successfully prepared by warm rolling and annealing. • Effects of initial grain size and texture on texture evolution were clarified. • Effects of initial grain size and texture on recrystallization nucleation and growth were analyzed. • Superior magnetic properties were obtained in the sheet with large initial grain size. Fe-6.5 wt% Si steel hot bands with different initial grain size and texture were obtained through different annealing treatment. These bands were then warm rolled and annealed. An analysis on the evolution of microstructure and texture, particularly the formation of recrystallization texture was studied. The results indicated that initial grain size and texture had a significant effect on texture evolution and magnetic properties. Large initial grains led to coarse deformed grains with dense and long shear bands after warm rolling. Such long shear bands resulted in growth advantage for {1 1 3} 3 6 1 oriented grains during recrystallization. On the other hand, sharp {11 h} 1, 2, 1/h (α^∗-fiber) texture in the coarse-grained sample led to dominant {1 1 2} 1 1 0 texture after warm rolling. Such {1 1 2} 1 1 0 deformed grains provided massive nucleation sites for {1 1 3} 3 6 1 oriented grains during subsequent recrystallization. These {1 1 3} 3 6 1 grains were confirmed to exhibit an advantage on grain growth compared to γ-fiber grains. As a result, significant {1 1 3} 3 6 1 texture was developed and unfavorable γ-fiber texture was inhibited in the final annealed sheet. Both these aspects led to superior magnetic properties in the sample with largest initial grain size. The magnetic induction B₈ was 1.36 T and the high frequency core loss P_10/400 was 17.07 W/kg.