| 摘要 |
PROBLEM TO BE SOLVED: To produce a grain-oriented silicon steel sheet capable of stably obtaining good magnetic properties by specifying the average grain size of primary recrystallized grains till the start of final finish annealing in a steel slab having a specified compsn. and the elongation of the steel sheet subjected to nitriding treatment and flattening annealing till the start of secondary recrystallization. SOLUTION: A slab contg., by weight, <=0.01% C, 1.0 to 4.0% Si, 1.0 to 6.0% Mn, <=0.010% S+0.405Se, 0.03 to 0.040% acid soluble Al, 0.0010 to 0.0130% N, and the balance Fe is heated at <1280 deg.C and is subjected to hot rolling. This hot rolled sheet is subjected to cold rolling and is subjected to primary recrystallization annealing, final finish annealing and flattening annealing to produce a grain-oriented silicon steel sheet. At this time, the average grain size of primarily recrystallized grains till the start of the final finish annealing after the completion of the primary recrystallization annealing is regulated to 8 to 30μm, nitriding treatment with >=0.0005% by increasing the amt. of nitrogen is executed till the start of secondary recrystallization in the final finish annealing after the hot rolling, and furthermore, by the flattening annealing, the elongation of the steel sheet is regulated to <=5%. |
