Method for producing grain-oriented electrical steel sheet

A method for producing a grain-oriented electrical steel sheet, the method comprising subjecting a slab having a chemical composition comprising, by mass %:

• C:
• 0.002% to 0.10%;
• Si:
• 2.5% to 6.0%;
• Mn:
• 0.01% to 0.8%;
• at least one group selected from the group consisting of:
• Group A:
• Al:
• 0.010% to 0.050%, and N:
• 0.003% to 0.020%;
• and
• Group B:
• at least one of S:
• 0.005% to 0.03%, and Se:
• 0.002% to 0.03%;
• and
• the remainder being Fe and inevitable impurities,
• to hot rolling, hot band annealing, one or two or more cold rollings sandwiching an intermediate annealing therebetween to form a steel sheet, formation of subscale on a surface of the steel sheet through decarburization annealing, application of an annealing separator composed mainly of MgO onto the steel sheet surface and finish annealing,
• wherein when a certain temperature within a range of 700 to 800° C. in a heating process of the decarburization annealing is T1 and a certain temperature as a soaking temperature within a range of 820 to 900° C. is T2, a heating rate R1 between 500° C. and T1 is set to not less than 80° C./s and a heating rate R2 between T1 and T2 is set to not more than 15° C./s,
• an oxygen potential PH2O/PH2 in an atmosphere up to the soaking temperature T2 in the decarburization annealing is within a range of 0.30 to 0.55, and
• a time of keeping a temperature in a range of T2 to 900° C. and making an oxygen potential PH2O/PH2 of the atmosphere to be not more than 0.10 is set to be not less than 5 seconds after the soaking treatment in the decarburization annealing.