| 摘要 |
PURPOSE:To inexpensively produce a grain-oriented silicon steel sheet excellent in cold workability and reduced in iron loss by subjecting a slab of a steel having a specific composition consisting of C, Si, Mn, S, Al, N, and Fe to rolling, to continuous annealing, and to specific finish annealing. CONSTITUTION:A slab of s steel which has a composition consisting of, by weight, <=0.01% C, 1.5-4.0% Si, 1.0-6.0% Mn, <=0.01% S, >0.015-0.030% sol. Al, 0.001-0.010% N, and the balance Fe with inevitable impurities and satisfying (Si-0.5Mn)<=0.2 is hot-rolled. The resulting hot rolled plate is subjected, in this state or after annealing, to cold rolling once or is cold-rolled two or more times while process-annealed between the cold rolling stages. The resulting steel sheet is subjected to primary recrystallization by continuous annealing. Further, the steel sheet is subjected to secondary recrystallization by primary finish annealing where the steel sheet is held in an N2-containing atmosphere at 825-925 deg.C for 7-50hr and then held at this temperature for 4-50hr in the atmosphere substituted by 100%H2 atmosphere. Then the steel sheet is purified by means of secondary finish annealing where the steel sheet is held in the H2 atmosphere at >925-1050 deg.C for 4-50hr. |
