| 摘要 |
A production method for grain-oriented electrical steel sheets in which a steel slab which includes, in mass%, 0.04-0.12% C, 1.5-5.0% Si, 0.01-1.0% Mn, 0.010-0.040% sol. Al, 0.004-0.02% N, and a total of 0.005-0.05% S and Se is processed through hot rolling, cold rolling, primary recrystallization annealing, and final annealing, wherein the ratio (sol. Al/N) of the content of sol. Al to N in the steel slab and the thickness (d(mm)) of the steel sheet during secondary recrystallization annealing satisfy the formula 4d+1.52≤sol. Al/N≤4d+2.32, and an ultrathin grain-oriented electrical steel sheet having low iron loss and minimal variation within the product coil is produced by maintaining the steel sheet prior to secondary recrystallization in the heating step of the final annealing at a temperature of 775-875°C for 40-200 hours, thereafter heating the sheet to a temperature range of 875-1050°C at a heating rate of 10-60°C/hr, and performing secondary recrystallization and purification treatment. |
