Patent ID: 8409368

Claim:
A manufacturing method of a grain-oriented electrical steel sheet, comprising: hot rolling a silicon steel material so as to obtain a hot-rolled steel strip, the silicon steel material containing Si: 0.8 mass % to 7 mass %, acid-soluble Al: 0.01 mass % to 0.065 mass %, N: 0.004 mass % to 0.012 mass %, Mn: 0.05 mass % to 1 mass %, Ti: 0.004 mass % or less and B: 0.0005 mass % to 0.0080 mass %, the silicon steel material further containing at least one element selected from a group consisting of S and Se being 0.003 mass % to 0.015 mass % in total amount, a C content being 0.085 mass % or less, and a balance being composed of Fe and inevitable impurities; annealing the hot-rolled steel strip so as to obtain an annealed steel strip; cold rolling the annealed steel strip one time or more so as to obtain a cold-rolled steel strip; decarburization annealing the cold-rolled steel strip so as to obtain a decarburized-annealed steel strip in which primary recrystallization is caused; coating an annealing separating agent containing MgO as its main component on the decarburized-annealed steel strip; and causing secondary recrystallization by finish annealing the coated decarburized-annealed steel strip, wherein the method further comprises performing a nitriding treatment in which an N content of the decarburized-annealed steel strip is increased between start of the decarburization annealing and occurrence of the secondary recrystallization in the finish annealing, wherein the hot rolling comprises: holding the silicon steel material in a temperature range from 1000° C. to 800° C. for 300 seconds or longer; and then performing finish rolling.