| 摘要 |
Grain-oriented electrical steel sheets with good magnetic properties are industrially stably produced, by using as the material, the steel slab having a composition consisting of, by mass% or mass ppm, C: 0.08 % or less, Si: 2.0 % to 4.5 %, 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: 80 ppm or less, and the balance being Fe and incidental impurities, and satisfying the relation of sol.Al (ppm) - N (ppm) x (26.98/14.00) ‰¤ 30 ppm, and by performing nitriding treatment, with a nitrogen increase (”N) being specified by the following formula (1) or (2), before, during or after primary recrystallization annealing, to precipitate silicon nitride (Si 3 N 4 ) at grain boundaries, and allowing the silicon nitride to act as inhibiting force for normal grain growth to significantly reduce variation of magnetic properties: when sol . Al - N × 26.98 / 14.00 ‰¤ 0 , 50 ppm ‰¤ ”N ‰¤ 1000 ppm
, or when 0 < sol . Al - N × 26.98 / 14.00 ‰¤ 30 , N - soll . Al × 14.00 / 26.98 + 100 ‰¤ ”N ‰¤ N - soll . Al × 14.00 / 26.98 + 1000 |
