Patent ID: 9187798
Filing Date: 2015-11-17
Classification: C21D,C22C,H01F

Abstract:
1. A method for manufacturing a grain oriented electrical steel sheet, comprising the steps of: subjecting a steel slab to heating and subsequent hot rolling to obtain a hot rolled steel sheet, the steel slab having a composition containing by mass %, C: 0.020% to 0.15% (inclusive of 0.020% and 0.15%), Si: 2.5% to 7.0% (inclusive of 2.5% and 7.0%), Mn: 0.005% to 0.3% (inclusive of 0.005% and 0.3%), acid-soluble aluminum: 0.01% to 0.05% (inclusive of 0.01% and 0.05%), N: 0.002% to 0.012% (inclusive of 0.002% and 0.012%), at least one of S and Se by the total content thereof being 0.05% or less, and the balance as Fe and incidental impurities; subjecting the hot rolled steel sheet to hot-band annealing under conditions of soaking temperature of 800° C. to 1200° C. (inclusive of 800° C. and 1200° C.) and soaking time of 2 seconds to 300 seconds (inclusive of 2 seconds and 300 seconds); and subjecting the hot rolled steel sheet to at least two cold rolling operations, which includes a final cold rolling, with intermediate annealing therebetween to obtain a cold rolled steel sheet having a final sheet thickness; and subjecting the cold rolled steel sheet to primary recrystallization annealing and then secondary recrystallization annealing, wherein a thermal treatment is carried out after the hot-band annealing and prior to at least one of the cold rolling operations so that the thermal treatment is not carried out immediately prior to the final cold rolling, wherein the thermal treatment is carried out at a temperature in the range of 500° C. to 750° C. (inclusive of 500° C. and 750° C.) for a period in the range of 10 minutes to 480 hours (inclusive of 10 minutes and 480 hours).