| 摘要 |
<p>Disclosed are a hot-rolled steel sheet for an oil pipeline and a manufacturing method thereof, wherein the hot-rolled steel sheet can have a high corrosion resistance and satisfy an API (American petroleum institute) 5L X70 standard through an allow element control and a process condition control. The manufacturing method of the hot-rolled steel sheet according to the present invention comprises: a step of reheating a slab sheet under the condition of an SRT (slab reheating temperature) of 1150 to 1250°C; a step of hot-rolling the reheated slab sheet under the condition of an FDT (finishing delivery temperature) of 750 to 850°C; and a step of coiling the hot-rolled sheet after cooling the hot-rolled sheet at a CT (coiling temperature) of 550 to 620°C, wherein the slab sheet comprises 0.03 to 0.06 wt% of C, 0.1 to 0.2 wt% of Si, 1.1 to 1.4 wt% of Mn, at most 0.01 wt% of P, at most 0.001 wt% of S, 0.02 to 0.05 wt% of Al, 0.04 to 0.1 wt% of V, 0.08 to 0.1 wt% of Nb, 0.01 to 0.03 wt% of Ti, 0.1 to 0.2 wt% of Mo, 0.1 to 0.3 wt% of Cr, 0.2 to 0.35 wt% of Cu, 0.1 to 0.3 wt% of Ni, 0.001 to 0.004 wt% of Ca, at most 0.006 wt% of N, and remnants Fe and inevitable impurities. [Reference numerals] (AA) Start; (BB) End; (S110) Reheat a slab (SRT: 1150 to 1250°C); (S120) Hot-roll (FDT: 750 to 850°C); (S130) Cool/coil (CT: 550 to 620°C)</p> |
