| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for stably producing a grain oriented magnetic steel sheet having industrially stable and good magnetic properties while avoiding high temperature re-heating of a slab.SOLUTION: The method for producing a grain oriented magnetic steel sheet is provided in which a slab containing, by mass%, C:0.002 to 0.08%, Si:2.0 to 8.0% and Mn:0.005 to 1.0%, sol.Al:less than 0.0150%, N:less than 0.0100%, S and Se:each reduced to less than 0.0050 is re-heated at 1250°C or less, then is hot-rolled, the resultant hot-rolled steel sheet is annealed and cold-rolled, the resultant cold-rolled steel sheet is subjected to primary recrystallization annealing serving also as decarburization annealing, then is subjected to nitriding treatment, an annealing separating agent is applied onto a steel sheet surface and the steel sheet is subjected to final annealing. In the method for producing the grain oriented magnetic steel sheet, soaking temperature in the hot-rolled sheet annealing is set to be 800 to 1100°C, an average temperature rising rate between 200°C and soaking temperature in the heating process is set to be 5°C/s or more and a ratio of a grain boundary in which an orientation difference angle of the steel sheet after the primary recrystallization is 20 to 45° to the whole grain boundary is set to be 65% or more. |
