| abstract |
A high-formability and super-strength cold-rolled steel sheet and a manufacturing method thereof. The weight percentage of its components is: C 0.15~0.25%, Si 1.00~2.00%, Mn 1.50~3.00%, P≤0.015%, S≤0.012%, Al 0.03~0.06%, N≤0.008%, and the rest are Fe and inevitable impurities. The manufacturing method comprises the following steps: 1) smelting and casting; 2) heating to 1170~1230˚C and performing thermal insulation; 3) performing hot rolling, the finish rolling temperature being 880±30˚C, and coiling at 550~650˚C; and 4) performing acid washing, cold rolling, and annealing, the cold rolling reduction being 40~60%, annealing at 860~920˚C, and performing slow cooling to 690~750˚C with the cooling rate of 3~10˚C/s; performing rapid cooling at 240~320˚C, with the cooling rate ≥50˚C/s, then heating to 360~460˚C, and performing thermal insulation for 100~500s to cool to the room temperature at last. Finally, a high-formability, low-rebound property and super-strength cold-rolled steel sheet with the yield strength of 600~900MPa, the tensile strength of 980~1150MPa, the elongation of 17~25% is obtained. |