| 摘要 |
PURPOSE:To produce a thermally hardenable zinc-plated steel plate haveing good press formability and weldability by subjecting steel contg. limited compsns. of C, Si, Mn, Sol.Al, P to rolling, zinc plating and cooling after an alloying treatment under adequate conditions. CONSTITUTION:The steel consisting of 0.003-0.20% C, <=0.30% Si, 0.05-0.60% Mn, <=0.08% Sol.Al, <=0.130% P, and if necessary, 1 or 2 kinds of <=0.05% V and <=0.05% Nb and the balance substantially Fe and unavoidable impurities is subjected to hot finish rolling at the rolling temp. higher than the Ar3 transformation point and coiling at <=780 deg.C, then to cold rolling at >=40% draft and heating above the recrystallization temp. After the heated steel plate is subjected to zinc hot dipping and an alloying treatment, the plated plate is cooled at >= 5 deg.C/min cooling rate whereby the thermally hardenable zinc-plated steel plate having >=5kg/mm.<2> rate of thermal hardening is obtained. |
