| 摘要 |
PROBLEM TO BE SOLVED: To industrially stably manufacture a grain oriented silicon steel sheet having good properties by depositing both silicon nitride (SiN) and MnS at the same time with using nitrosulphurizing, using both silicon nitride and MnS as restraint of normal grain growing, and largely reducing variations of magnetic properties.SOLUTION: When a grain oriented silicon steel sheet is manufactured with a raw material of a steel slab having a composition of, by mass%, C:0.08% or less, Si:2.0 to 4.5% and Mn:0.5% or less, limited S, Se and O each of less than 50 ppm, limited sol.Al of less than 100 ppm, and controlled of N with [sol.Al]×(14/27) ppm≤N≤80 ppm, and the balance Fe with inevitable impurities, a nitrosulphurizing treatment is conducted so that the content of nitrogen is 50 ppm to 1000 ppm and the amount of S is over 20 ppm and 800 ppm or less by initiation of secondary recrystallization firing after cold rolling and then 5 hours or longer of retention time in a temperature range of 300 to 800°C during a heating up process of the secondary recrystallization firing is secured. |
