| 摘要 |
PROBLEM TO BE SOLVED: To provide a method of stably manufacturing, at a low cost, a grain oriented silicon steel sheet having low iron loss and high magnetic flux density. SOLUTION: A slab, having a chemical composition which consists of <=0.01% C, 1.5-4% Si, 1-5% Mn, <=0.01% S, 0.003-0.03% sol. Al. 0.001-0.01% N, and the balance Fe with inevitable impurities and in which Si and Mn satisfy the relation of Si(%)-0.5×Mn(%)<=2, is hot-rolled. The resultant plate is cold-rolled by the single cold rolling process at 40-90% draft or the double cold rolling process where process annealing is included and the draft at a second cold rolling is 55 to 80%. The resultant sheet is subjected to primary recrystallization annealing and then to finish annealing at 825 to 1050 deg.C for 4 to 200 hr. At this time, in the course of heating up to the finish annealing temp., the sheet is held at 700 to 825 deg.C for 2 to 48 hr in a nonoxidizing atmosphere containing >=2% nitrogen. |
