| 摘要 |
The present invention relates to a development of tolerance for a steel sheet for an oil pipe utilized as an oil pipeline to transfer crude oil and, more specifically, relates to a high-strength steel sheet capable of enduring high underground pressures and a manufacturing method thereof. The method to manufacture the high-strength steel sheet comprises: (a) a step of reheating a steel slab comprising 0.04-0.12 wt% of C, 0.1-0.4 wt% of Si, 1.5-2.0 wt% of Mn, 0.015 wt% or less of P, 0.002 wt% or less of S, 0.04-0.1 wt% of Nb, 0.001-0.025 wt% of Ti, 0.05-0.4 wt% of Ni, 0.001-0.35 wt% of Cr, and the remainder consisting of Fe and inevitable impurities at a slab reheating temperature (SRT) of 1200-1250°C; (b) a step of hot-rolling the reheated slab at a finishing delivery temperature (FDT) of 730-850°C; and (c) a step of cooling the hot-rolled steel at a coiling temperature of 400-500°C, and coiling the cooled hot-rolled steel. |
