| 摘要 |
PURPOSE:To stably obtain good magnetic properties even if hot rolled sheet annealing is obviated by controlling the amt. of AlN to be precipitated in a hot rolled steel sheet in which C, Si, Al, N, S or the like are specified and the average grain size of primarily recrystallized grains, subjecting it to hot rolling and thereafter executing nitriding treatment. CONSTITUTION:A steel contg., by weight, <=0.075% C, 2.2 to 4.5% Si, 0.01 to 0.06% acid soluble Al, <=0.0l3% N, S+0.405Se; <=0.014%, 0.05 to 0.8% Mn, and the balance Fe 15 melted. The slab of this steel is heated to <1280 deg.C and is subjected to hot rolling, and in the case the N content as AlN in the hot rolled sheet is defined as NasAlN, N-(NaSAlN); <=0.03% and (NasAlN)/N; >=0.55% are satisfied. Successively, it is subjected to final forced draft cold rolling at >=80% draft without executing hot rolled sheet annealing. Next, after the completion of decarburizing annealing, the average grain size of primarily recrystallized grains till the start of final finish annealing is regulated to 18 to 35mum, and nitriding treatment is executed till the start of secondary recrystallization in final finish annealing. |
