| 摘要 |
Grain-oriented electrical steel sheets with good magnetic properties are industrially stably produced, by using as the material, a steel slab having a composition consisting of, by mass% or mass ppm, C: 0.08 % or less, Si: 2.0 % to 4.5 % and Mn: 0.5 % or less, S: less than 50 ppm, Se: less than 50 ppm,O: less than 50 ppm, sol.Al: less than 100 ppm, N in a range satisfying [sol.Al] × (14/27) ppm ‰¤ N ‰¤ 80 ppm, and the balance being Fe and incidental impurities, wherein after cold rolling and before the start of secondary recrystallization annealing, the cold rolled sheet is subjected to nitriding treatment to obtain a nitrogen content of 50 mass ppm or more and 1000 mass ppm or less, and a total content of 0.2 mass% to 15 mass% of a sulfide and/or sulfate is contained in an annealing separator, and a staying time in the temperature range of 300 °C to 800 °C in the heating stage of secondary recrystallization annealing of 5 hours or more is secured to precipitate silicon nitride (Si 3 N 4 ) and MnS, and using the silicon nitride in combination with MnS as inhibiting force for normal grain growth to significantly reduce variation of magnetic properties. |
