Method for manufacturing a grain-oriented electrical steel sheet

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

• providing a steel slab, the steel slab having a chemical composition containing, in mass %,
• C:
• 0.025% or more and 0.060% or less,
• Si:
• 3.0% or more and 4.0% or less,
• Mn:
• 0.05% or more and 0.50% or less,
• sol. Al:
• less than 0.01%,
• N:
• less than 0.006%, and
• S and Se:
• less than 0.010% in total,
• with the balance being Fe and inevitable impurities;
• optionally heating the steel slab to a heating temperature of 1300° C. or less;
• subjecting the steel slab to hot rolling to obtain a hot-rolled steel sheet;
• subjecting the hot-rolled steel sheet to hot band annealing;
• subjecting the hot-rolled steel sheet annealed by the hot band annealing, to cold rolling to obtain a cold-rolled steel sheet with a final sheet thickness;
• subjecting the cold-rolled steel sheet to primary recrystallization annealing to obtain a primary recrystallized steel sheet;
• applying an annealing separator to the primary recrystallized steel sheet;
• coiling the primary recrystallized steel sheet to which the annealing separator has been applied, to obtain a coil;
• subjecting the coil to secondary recrystallization annealing, and
• thereby producing the grain-oriented electrical steel sheet, wherein the grain-oriented electrical steel sheet has a carbon content of 0.005 mass % or less, an average value of a deviation angle
• (
• α
• 2
• +
• β
• 2
• )
• 1
• /
• 2
• calculated from a deviation angle α from ideal Goss orientation around an ND rotation axis and a deviation angle β from ideal Goss orientation around a TD rotation axis of 4.5° or less and an area ratio R62 of crystal grains with β≤0.50° of 15% or less,
• wherein
• a residence time from 900° C. to 700° C., t900-700° C., in an annealing before a final cold rolling is 6 seconds or more and 180 seconds or less,
• an area ratio Rc of carbide with a particle size of 1 μm or more at start of final cold rolling in the cold rolling is 2.0% to 15%,
• an average crystal grain size D at the start of the final cold rolling is 50 μm or more and 300 μm or less, and
• a maximum temperature Tmax in the final cold rolling is 150° C. or more.