Microstructure and Magnetic Properties of Strip-Casting Non-oriented Silicon Steel at Different Cold Rolling and Annealing Processes

A 1.5 mm thickness Fe-1.3%Si non-oriented silicon steel as-cast strip produced by strip casting was cold rolled at different reductions (56.7%, 66.7%, 76.7%) and annealed at different temperatures (800, 850, 900, 950 ℃) and time (1, 3, 5, 7 min). The microstructure, precipitate and magnetic properties of the silicon steel were investigated. The results show that MnS particles with size of 30-40 nm were the main precipitate during annealing, which had significantly pinning effect on grain. The magnetic induction B50 of annealed silicon steel maintained at 1.77-1.80 T. With the increase of cold rolling reduction from 56.7% to 76.7%, the average size of recrystallized grains refined obviously and core loss P15/50 decreased from 5.54 W·kg-1 to 4.23 W·kg-1. Relatively large recrystallized grains were obtained when the cold rolled silicon steel with 66.7% reduction was annealed at 900 ℃ for 5 min, leading to the optimal magnetic properties (P15/50= 4.54 W·kg-1).