| 摘要 |
PURPOSE:To produce the steel sheet improved in magnetic properties and film characteristics by specifying heating temp. and also specifying the temp. and atmosphere in finish annealing at the time of producing a grain-oriented silicon steel sheet from a slab of a silicon steel having a specific composition in which S content is specified. CONSTITUTION:A slab of a silicon steel having a composition consisting of, by weight, 0.025-0.075% C, 2.5-4.5% Si, <=0.012% S, 0.010-0.060% acid-soluble Al, <=0.010% N, 0.08-0.45% Mn, and the balance Fe with inevitable impurities is heated up to <=1200 deg.C and hot-rolled, and the resulting plate is cold-rolled once or is subjected to cold rolling twice or more while process-annealed between the cold rolling stages so as to be formed into the final sheet thickness. Subsequently, the resulting sheet is subjected to decarburizing annealing and is then subjected to nitriding treatment in the state where the strip is allowed to travel, and, after a separation agent at annealing is applied, finish annealing is performed while regulating the atmosphere in the temp. region up to 800-850 deg.C in high temp. finish annealing so that it has a composition consisting of >=30% (N2+Ar), where N2 is >=25%, and the balance H2 and also regulating the atmosphere in the temp. region beyond the above temp. region so that it is the same as the atmosphere in the conventional finish annealing for grain-oriented silicon steel sheet. |
