| 摘要 |
PURPOSE:To improve the magnetic property of an electromagnetic steel and to avoid generations of surface defects, by increasing Mn content in the surface layer of the steel sheet and lowering Mn content in the core part of the steel sheet. CONSTITUTION:An electromagnetic steel material containing less than 0.065wt% C, less than 4.5wt% Si and 0.005-0.1wt% S and/or Se, is hot rolled. The hot rolled sheet is cold rolled to a final thickness, by one pass or by two or more passes accompanied with an intermediate annealing in a temperature range of 800-1,100 deg.C. The cold rolled steel sheet is then decarburized, coated with a partition agent, and annealed. Thus, a unidirectional electromagnetic steel sheet is produced. In this process, the Mn content X% in the surface layer, which accounts for 1-20% of the total thickness of the steel material before the hot rolling, satisfies the relation represented by the formula with the Mn content Y% in the core layer inside the surface layer. In this formula, X is in the range if 0.02-0.075%. |
