发明授权
US4708748A Method of making cold rolled dual-phase structure steel sheet having an excellent deep drawability 失效
制造具有优异深冲性的冷轧双相结构钢板的方法

Method of making cold rolled dual-phase structure steel sheet having an
excellent deep drawability
摘要:
A cold rolled dual-phase structure steel sheet having an excellent deep drawability is disclosed, which consists of ferrite phase and low temperature transformation product phase and comprises 0.001-0.008 wt % of C, not more than 1.0 wt % of Si, 0.05-1.8 wt % of Mn, not more than 0.15 wt % of P, 0.01-0.10 wt % of Al, 0.002-0.050 wt % of Nb and 0.0005-0.0050 wt % of B provided that the value of Nb(%)+10B(%) is in a range of 0.010-0.080%, and, if necessary, 0.05-1.00 wt % of Cr and the balance being substantially Fe with inevitable impurities. This steel sheet is manufactured by hot and cold rolling a steel slab with the above chemical composition and continuously annealing the resulting steel sheet in such a manner than the steel sheet is heated and soaked at a temperature from .alpha..fwdarw..gamma. transformation point to 1,000.degree. C. and then cooled at an average cooling rate of not less than 0.5.degree. C./sec but less than 20.degree. C./sec in a temperature range of from the soaking temperature to 750.degree. C., and subsequently at an average cooling rate of not less than 20.degree. C./sec in a temperature range of from 750.degree. C. to not more than 300.degree. C.
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