| 摘要 |
PROBLEM TO BE SOLVED: To stably produce a grain-oriented silicon steel sheet excellent in magnetic properties by rolling a silicon steel slab having a specified compsn. composed of C, Si, Mn, S, Se, Al, N, Mo and Fe and thereafter executing nitriding treatment. SOLUTION: A silicon steel slab contg., by weight, 0.020 to 0.075% C, 2.5 to 5.0% Si, 0.05 to 0.45% Mn, <=0.15% S or Se, 0.010 to 0.050% acid soluble Al, 0.0035 to 0.012% N and 0.005 to 0.08% Mo, furthermore contg., at need, 0.02 to 0.15% Sn and 0.03 to 0.20% Cr, and the balance Fe with inevitable impurities is heated at <=1280 deg.C, is thereafter subjected to hot rolling and is subjected to hot rolled sheet annealing according to necessary. This hot rolled sheet is subjected to cold rolling for one time or >= two times including process annealing, and the final rolling ratio is regulated to >=80%. This cold rolled sheet is subjected to decarburizing annealing, is allowed to run at 650 to 850 deg.C in a gaseous mixture of H2 , N2 and NH3 , is subjected to nitriding treatment so as to regulate the content of N to >=120ppm and is subsequently subjected to finish annealing. |
