| 摘要 |
PURPOSE:To manufacture a high-tension cold-rolled steel sheet having superior cold workability and weldability by hot rolling and cold rolling a steel contg. specified percentages of C, Si, Mn, Ti, Nb and B and by annealing the cold rolled steel sheet under specified conditions. CONSTITUTION:A steel consisting of, by weight, 0.05-0.20% C, <=1.0% Si, 1.4- 2.6% Mn, 0.01-0.25% Ti and/or 0.01-0.30% Nb, 0.0003-0.0100% B and the balance Fe with inevitable impurities is hot rolled and cold rolled as usual. The cold rolled steel sheet is annealed by holding at the A1 transformation point - 900 deg.C for 1sec-500min and cooling at 100-500 deg.C/sec average cooling rate. A high-tension cold-rolled steel sheet having 80-150kgf/m<2> tensile strength, superior cold workability and weldability is obtd. |
