GRAIN-ORIENTED ELECTROMAGNETIC STEEL SHEET EXCELLENT IN COATING ADHESION AND RUST RESISTANCE, ORIGINAL SHEET FOR GRAIN-ORIENTED ELECTROMAGNETIC STEEL SHEET AND METHOD FOR MANUFACTURING THEM

摘要

PROBLEM TO BE SOLVED: To provide a grain-oriented electromagnetic steel sheet having a structure of a glass coating controlled and satisfying both of applied tension, and adhesiveness and rust resistance; and an original sheet for the grain-oriented electromagnetic steel sheet; and a method for manufacturing them.;SOLUTION: The grain-oriented electromagnetic steel sheet includes a coating mainly including forsterite having an average particle size of 2.0 μm or less between an insulating film and a mother steel sheet. In a manufacturing process comprising the steps of hot-rolling a steel slab, annealing the hot-rolled plate if necessary, cold-rolling it to a thickness of the final-product, decarbonizing and annealing it, nitriding and annealing it if necessary, annealing it for final finish, and subjecting it to an insulating film treatment, a temperature elevation in the decarbonizing and annealing is performed in an atmosphere of PH₂O/PH₂=0.65-3.0 at a heating-rate of 100°C/s or more and a heating temperature of 800°C or more, a residence time at 750°C or more is set to not more than 5 seconds, and the decarbonization is continually performed in an atmosphere of P(H₂O)/P(H₂)=0.25-0.6 with a maximum arrival temperature Y of 700-900°C, a residence time of not more than 4 seconds at a temperature of more than Y-30°C, and a residence time of not less than 10 seconds at Y-30°C to Y-85°C after the maximum temperature arrival.;SELECTED DRAWING: Figure 1;COPYRIGHT: (C)2017,JPO&INPIT