Manufacturing method of grain-oriented magnetic steel sheet

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.