| 摘要 |
<p>Disclosed are a hot rolled steel sheet for a steel pipe and a method to manufacture a steel pipe capable of improving grooving corrosive properties of an electric resistance welding part through the adjustment of alloy components and the control of process conditions. According to the present invention, the method to manufacture the steel pipe comprises: a step of re-heating a steel slab, by weight%, including 0.05-0.18% of C, 0.025% or less of Si, 0.30-0.60% of Mn, 0.020% or less of P, 0.005% or less of S, 0.08-0.30% of Cu, 0.08-0.30% of Ni, 0.08-0.30% of Cr, 0.0010-0.0060% of Ca, and the remainder consisting of Fe and inevitable impurities at the slab re-heating temperature (SRT) of 1220-1300°C; a step of hot rolling the re-heated sheet at the finish delivery temperature (FDT) of 860-900°C; a step of coiling the hot rolled sheet by cooling the sheet; a step of normalizing the wound sheet during 10-30 minutes at 800-900°C by un-coiling the sheet; a step of forming a steel pipe by welding the sheet in an electric resistance welding method after cutting the normalized sheet; and a post-weld heat treatment (PWHT) step of heat treating the sheet after welding the welded steel pipe at 520-620°C.</p> |
