| 摘要 |
PURPOSE:To manufacture the titled steel sheet superior in ductility and workability, by applying hot rolling, pickling, cold rolling and continuous annealing to steel slab, then cooling and holding the sheet at a specified temp. range, then cooling it up to room temp. CONSTITUTION:Continuously cast slab of molten steel contg. by weight, 0.1-0.3% C, 0.25-2.0% Si, 1.5-2.5% Mn, <0.010% P, <0.003% S, 0.02-0.10% sol. Al, or further 0.0002-0.0030% Ca is hot rolled conventionally, the scale is removed by pickling, and the plate is cold rolled to steel strip having 1.4mm thickness. This is annealed continuously at >=750 deg.C, then cooled to 350-500 deg.C range by 3-70 deg.C/sec rate. The sheet is held at the temp. range for time range satisfying a formula (1), then cooled to room temp. The titled steel sheet superior in ductility and workability, having >80kgf/mm<2> tensile strength, >16% elongation, min. bending radius r(mm) of >=two times the sheet thickness t(mm) can be manufactured.
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