Hot-rolled steel sheet for grain-oriented electrical steel sheet and method of producing same, and method of producing grain-oriented electrical steel sheet

A hot-rolled and annealed sheet for a grain-oriented electrical steel sheet, comprising:

• a chemical composition containing, by mass %,
• C:
• 0.002% or more and 0.080% or less,
• Si:
• 2.00% or more and 8.00% or less,
• Mn:
• 0.02% or more and 0.50% or less,
• acid-soluble Al:
• 0.003% or more and less than 0.010%, and
• at least one of S or Se:
• 0.001% or more and 0.010% or less in total,
• with N limited to less than 0.006%, and the balance being Fe and inevitable impurities, wherein
• an average recrystallized grain size in regions from an outermost surface layer and a bottommost surface layer to a depth of 1/4 sheet thickness is three times or less an average recrystallized grain size in regions from a center of the sheet thickness to a length of less than 1/4 sheet thickness in directions to the outermost surface layer and the bottommost surface layer.

A method of producing a hot-rolled steel sheet for a grain-oriented electrical steel sheet, comprising:

• preparing a steel slab having a chemical composition containing, by mass %,
• C:
• 0.002% or more and 0.080% or less,
• Si:
• 2.0% or more and 8.0% or less,
• Mn:
• 0.02% or more and 0.50% or less,
• acid-soluble Al:
• 0.003% or more and less than 0.010%, and
• at least one of S or Se:
• 0.001% or more and 0.010% or less in total,
• with N limited to less than 0.006%, and the balance being Fe and inevitable impurities;
• heating the steel slab to 1300° C. or lower;
• and
• subjecting the steel slab to hot rolling, wherein a friction coefficient in final pass of the hot rolling is 0.35 or less.