1 PRODUCTION METHOD FOR GRAIN-ORIENTED ELECTRICAL STEEL SHEET AND PRIMARY RECRYSTALLIZED STEEL SHEET FOR PRODUCTION OF GRAIN-ORIENTED ELECTRICAL STEEL SHEET

摘要

C, S, and O in an amount of less than 50 ppm and less than 50 ppm, respectively, in terms of mass% or mass ppm, C: more than 0%, less than 0.08%, Si: 2.0 to 4.5% controlling the content of sol.Al to less than 100 ppm and further controlling N in the range of sol.Al/(26.98/14.00) ppm? N? 80 ppm, and the balance of Fe and inevitable impurities , And after the reheating is not performed or the reheating is performed, the hot rolled sheet is formed into a hot rolled sheet by hot rolling, followed by annealing and rolling to obtain a cold rolled sheet having a final sheet thickness. Subsequently, during or after the first recrystallization annealing, And the annealing separator is applied. In the temperature raising process of the second recrystallization annealing, the retention time between 300 and 800 ° C is set to not less than 5 hours and not more than 150 hours, and silicon nitride (Si ₃ N ₄ ) is precipitated on the grain boundary, and By functioning as a suppressing force of normal grain growth, silicon nitride significantly reduces variations in magnetic properties and industrially stably produces a grain-oriented electrical steel sheet having good characteristics.