Method for manufacturing grain-oriented electrical steel sheet and grain-oriented electrical steel sheet

A grain-oriented electrical steel sheet, comprising:

• a silicon steel sheet;
• a forsterite coating disposed on the silicon steel sheet;
• and
• an insulating film disposed on the forsterite coating,
• wherein the silicon steel sheet has a component composition containing, by mass %,
• Si:
• 2.5% or more and 4.5% or less,
• Mn:
• 0.01% or more and 0.15% or less,
• C:
• 0% or more and 0.0050% or less,
• S and Se in total:
• 0% or more and 0.005% or less,
• acid-soluble Al:
• 0% or more and 0.01% or less,
• N:
• 0% or more and 0.005% or less
• Cu:
• 0% or more and 0.30% or less,
• Sn:
• 0% or more and 0.30% or less,
• Ni:
• 0% or more and 0.30% or less,
• Cr:
• 0% or more and 0.30% or less, and
• Sb:
• 0% or more and 0.30% or less,
• with a remainder including Fe and impurities,
• an average grain size of secondary recrystallized grains in the silicon steel sheet is 10 mm or more and 50 mm or less, and
• the grain-oriented electrical steel sheet has
• a sheet thickness of 0.15 mm or more and 0.23 mm or less,
• an iron loss Wp of 0.790 W/kg or less in terms of W17/50,
• Wp/Wd of 1.03 or more and 1.15 or less in term of W17/50, the Wp/Wd being a ratio of the iron loss Wp to an iron loss Wd in the case of being magnetic domain-refined, and
• a magnetic flux density B8 value of 1.930 T or more.