| 摘要 |
PURPOSE: A cold-rolled steel plate or strip has high strength and good formability, especially, rolling formability in order to produce a pressed article having high bucking resistance. CONSTITUTION: The pressed article of high bucking resistance comprises:0.01 to 0.04 wt.% of Ti and/or Nb; at most 0.15 wt.% of at least one component selected from the consisting of copper, vanadium and nickel; at most 0.08 wt.% of P; and at most 0.02 wt.% of S, within the range of 0.01 to 0.08 wt.% of C, 0.10 to 0.80 wt.% of Mn, at most 0.60 wt.% of Si, 0.015 to 0.08 wt.% of AL, at most 0.005 wt.% of N, 0.003 to 0.015 wt.% of Ti or 0.0015 to 0.008 wt.% of Nb. The cold-rolled steel plate or strip manufacturing method comprises the steps of:preheating a major strip at a temperature exceeding 550 to 1050°C; hot-rolling the strip on Ar3 at the final temperature of 950°C; coiling the hot-rolled strip at 550 to 750°C; cold-rolling the strip at a temperature of high than 720°C; cooling the cold-rolled strip at 5 to 70 K/s; and forming a coarse rolled strip.
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