Patent ID: 9640320
Date: 2017-05-02
CPC Classifications: C21D,C22C,H01F

Claim:
1. A method of producing a grain-oriented electrical steel sheet having forsterite film by subjecting a coil for grain-oriented electrical steel sheet after cold rolling to a primary recrystallization annealing, applying an annealing separation agent composed mainly of MgO thereon, and conducting final annealing, wherein for the primary recrystallization annealing rapid heating is conducted at a rate of not less than 80° C./sec from 500° C. to 700° C., and for the final annealing a temperature keeping treatment is conducted for 2 to 100 hours by maintaining a constant keeping temperature from 700° C. to 1000° C. and subsequently the temperature is raised up to 1180° C. or more and then kept at a constant temperature, and wherein the shape defect rate is 2.8% or less.