Patent ID: 9663839
Date: 2017-05-30
CPC Classifications: C21D,C22C

Claim:
1. A method for manufacturing a grain-oriented electrical steel sheet, the method comprising: heating a grain-oriented electrical steel sheet slab; hot-rolling the heated slab; optionally annealing the hot-roiled steel sheet; subjecting the hot-rolled steel sheet to one cold rolling or two or more cold roilings with intermediate annealing therebetween; subjecting the cold-rolled steel sheet to primary recrystallization annealing; and subjecting the annealed steel sheet to secondary recrystallization annealing, wherein the primary recrystallization annealing sequentially comprises a first heating process of heating the steel sheet to a temperature, Ts °C., which is below a recrystallization temperature of the steel sheet, at an average heating rate of 300° C./sec or higher, wherein Ts °C. is 500-600° C., a second heating process of heating the steel sheet at a lower average heating rate than the average heating rate of the first heating process, but not lower than 100° C./sec, and a third heating process of heating the steel sheet at a lower average heating rate than the average heating rate of the second heating process.