Effect of Cold Rolling Reduction Ratio on Microstructure and Magnetic Properties of Secondary Cold-Rolled High-Grade Nonoriented Silicon Steel

Trial production of 0.25 mm-thick thin-gauge high-grade nonoriented silicon steel with a Si content of 3.5% by the secondary cold rolling process is studied. The recrystallization microstructure and magnetic properties are systematically studied by the microstructure, texture evolution, and the effect of two-stage cold rolling reduction ratios (37.5-70.5%) during the whole process. The results show that the magnetic induction intensity B-5000 first increases and then decreases; the iron loss first decreases and then increases at the frequencies of 50 and 400 Hz with the reduction of the cold rolling reduction rate in the second stage. The cubic and Goss texture of the finished annealed sheet has the highest strength when the reduction ratio of the second stage cold rolling is 58.3%. The highest magnetic induction intensity, B-5000 = 1.671 T. Lowest iron loss, P-1.0/50 = 0.83 W kg(-1), P-1.5/50 = 1.98 W kg(-1), and P-1.0/400 = 11.94 W kg(-1), respectively.