| 摘要 |
PURPOSE:To manufacture a high-strength cold rolling steel sheet which is excellent in surface state and cold workability by bringing low carbon steel which limits the upper limit of Si and Mn, to hot rolling and heat treatment under a specified condition, and bringing it to box annealing after pickling and cold rolling. CONSTITUTION:Steel which contains <=0.15% C, <=3% Si, <=2% Mn, and contains one or both of <=1% Cu and 0.03-0.13% P as necessary, and 0.5-4% Si+Mn, and the balance iron with inevitable impurites is treated as mentioned below. That is to say, this steel is hot-rolled at a finish temperature exceeding an Ar3 transformation point, is cooled at >=30 deg.C/second speed, and is wound. Subsequently, it is held at a temperature exceeding 500 deg.C. Subsequently, after pickling and also cold rolling, its box annealing is executed at 650-800 deg.C temperature. |
