| 摘要 |
<p>Disclosed are a hot rolled steel sheet for a pipe satisfying an API-X70 standard without reducing a yield strength when a pipe is manufactured; and a method to manufacture the same. According to the present invention, the method to manufacture the hot rolled steel sheet for a pipe comprises: a step of re-heating a slab comprising, by wt%, 0.03-0.12% of carbon (C), 0.2-0.4% of silicon (Si), 1.4-1.8% of manganese (Mn), 0.03% or less of phosphorus (P), 0.01% or less of sulfur (S), 0.01% or less of nitrogen (N), 0.02-0.06% of niobium (Nb), 0.01-0.04% of titanium (Ti), 0.05-0.5% of nickel (Ni), 0.1-0.5% of chrome (Cr), 0.1% or less of molybdenum (Mo), and the remainder consisting of iron (Fe) and inevitable impurities at 1180-1300°C which is a slab reheating temperature (SRT); a step of hot rolling the re-heated slab at 800-880°C which is a finishing rolling temperature (FRT); and a step of coiling the slab by cooling the hot rolled slab at 500-570°C which is a coiling temperature (CT).</p> |
