| 摘要 |
A process for producing a grain-oriented electromagnetic steel sheet using, as a raw material therefor, a steel slab having a composition which contains, in terms of mass% or mass ppm, up to 0.08% C, 2.0-4.5% Si, and up to 0.5% Mn, has S, Se, and O contents reduced to below 50 ppm each and a sol.Al content reduced to below 100 ppm, and has an N content regulated to the range [sol.Al]×(14/27) ppm≤N≤80 ppm, with the remainder comprising Fe and unavoidable impurities, the process comprising cold-rolling the steel slab, thereafter subjecting the steel slab, before initiation of secondary recrystallization/annealing, to a nitriding treatment whereby the nitrogen content is regulated to 50-1,000 mass ppm, incorporating a sulfide and/or a sulfate into an annealing separator in a total amount of 0.2-15 mass%, and conducting secondary recrystallization/annealing so that the steel slab, during the heating, is held for 5 hours or longer in the temperature range of 300-800ºC, thereby precipitating silicon nitride (Si3N4) and MnS and using the silicon nitride and the MnS in combination as a power of inhibiting the growth of normal grains. Thus, unevenness in magnetic property is greatly reduced, and a grain-oriented electromagnetic steel sheet having satisfactory characteristics is industrially stably produced. |
