| 摘要 |
<p>PURPOSE: A steel plate manufacturing method is provided to heat-process a steel plate with a box-annealing method after cold-rolling, thereby obtaining a stable mass-flow and a sound shape of the steel plate. CONSTITUTION: A steel pipe manufacturing method comprises a hot-rolling step(S100) for hot-rolling a slab steel plate comprising 0.20-0.23 wt% of C, 1.65-1.75 wt% of Mn, 0.07-0.15 wt% of Si, 0.020-0.065 wt% of P, 0.010 wt% or less of S, 0.18-0.25 wt% of V, and the rest of Fe and unavoidable impurities at a temperature of 850-950°C; a cooling-coiling step(S200) for coiling the hot-rolled slab steel plate after cooling at a CT(Coiling Temperature) of 550-700°C; a cold-rolling step(S300) for cold-rolling the coiled steel plate after coil-withdrawing out the same; and an annealing step for annealing the cold-rolled slab steel plate with a box-annealing method. [Reference numerals] (AA) Start; (BB) End; (S100) Hot rolling(FDT: 850-950°C); (S110) Slab reheating(SRT: 1150-1250°C); (S200) Cooling/coiling(CT: 550-700°C); (S300) Cold-rolling; (S310) Pickling; (S400) Annealing</p> |
