| 摘要 |
PURPOSE:To improve magnetic properties by specifying average temp. rise rate, maximum temp., and annealing time, respectively, at the time of applying recrystallization annealing to a nonoriented silicon steel sheet with a specific composition after cold rolling. CONSTITUTION:The nonoriented silicon steel sheet has a composition consisting of, by weight ratio, <=0.01% C, <=0.01% N, <=3.5% Si, <=0.15% P, <=0.01% S, <=1.0% Al, and the balance essentially Fe. At the time of recrystallization annealing after the cold rolling of this steel sheet, the average temp. rise rate between 500 deg.C and maximum annealing temp. is regulated to >=300 deg.C/sec. The maximum annealing temp. is regulated to a temp. between 750 deg.C and a temp. T deg.C having a relationship, with Si content, represented by T( deg.C)=910 +50 Si(%), and also the annealing time at >=50 deg.C is regulated to <=10sec. Further, it is preferable that, in the steel composition, B is incorporated so that B/N becomes <=1.5. By this method, the nonoriented silicon steel sheet having superior magnetic properties can be obtained by means of short-time annealing. |
