Production method for grain-oriented electrical steel sheet

A production method for a grain-oriented electrical steel sheet, the production method comprising:

• hot rolling a steel slab to obtain a hot-rolled sheet, the steel slab having a chemical composition containing, in mass %,
• C:
• 0.01% to 0.10%,
• Si:
• 2.0% to 4.5%,
• Mn:
• 0.01% to 0.5%,
• Al:
• less than 0.0100%,
• S:
• 0.0070% or less,
• Se:
• 0.0070% or less,
• N:
• 0.0050% or less, and
• O:
• 0.0050% or less, and optionally one or more selected from the group consisting of
• Ni:
• 0.005% to 1.50%,
• Sn:
• 0.01% to 0.50%,
• Sb:
• 0.005% to 0.50%,
• Cu:
• 0.01% to 0.50%,
• Mo:
• 0.01% to 0.50%,
• P:
• 0.0050% to 0.50%,
• Cr:
• 0.01% to 1.50%,
• Nb:
• 0.0005% to 0.0200%,
• B:
• 0.0005% to 0.0200%, and
• Bi:
• 0.0005% to 0.0200%,
• with a balance consisting of Fe and inevitable impurities;
• annealing the hot-rolled sheet to obtain a hot-rolled and annealed sheet;
• cold rolling the hot-rolled and annealed sheet one time, two times with intermediate annealing being performed therebetween, or more than two times with the intermediate annealing being performed between each of two consecutive cold rollings, to obtain a cold-rolled sheet having a final sheet thickness;
• and
• subjecting the cold-rolled sheet to primary recrystallization annealing and secondary recrystallization annealing,
• wherein in the cold rolling, a rolling reduction ratio is 80% or more at least one time out of the one time, the two times, or the more than two times,
• wherein the cold rolling is performed using a tandem mill and involves variations in rolling rate relative to a set value R0 in meters per minute (mpm),
• wherein the hot-rolled and annealed sheet is heated on an entry side of the tandem mill so that a steel sheet temperature T0 in ° C. at the entry side of the tandem mill is maintained while the rolling rate is the set value R0 and a steel sheet temperature T1 in ° C. at the entry side of the tandem mill is maintained while the rolling rate is less than or equal to 0.5×R0, and
• wherein the steel sheet temperatures T0 and T1 satisfy a formula:
• T
• 1
• ≥
• T
• 0
• +
• 10
• ⁢
• °
• ⁢
• C
• .
• (
• 1
• )