| 摘要 |
<p>The present invention relates to a hot rolled steel sheet capable of satisfying the API 5L X70 PSL2 standard (the tensile strength (TS) is 600 MPa or more, and the yield strength (YP) is 555 MPa or more), and ensuring the hydrogen induced cracking resistance; and a method for manufacturing the same. According to the present invention, the method for manufacturing the hot rolled steel sheet comprises: a step of re-heating a steel slab comprising, by weight%, 0.03-0.07 wt% of carbon (C), 0.2 wt% or less of silicon (Si), 0.5-1.5 wt% of manganese (Mn), 0.02-0.05 wt% of aluminum (Al), 0.07-0.1 wt% of niobium (Nb), 0.01-0.02 wt% of titanium (Ti), 0.2-0.45 wt% of chrome (Cr), 0.2-0.35 wt% of copper (Cu), 0.1-0.3 wt% of nickel (Ni), 0.001-0.003 wt% of calcium (Ca), and the remainder consisting of Fe and inevitable impurities at 1200-1250°C which is a slab re-heating temperature (SRT); a hot rolling step of secondarily rolling the slab at 800-850°C which is a finish rolling temperature (FRT) after the re-heated slab is primarily rolled at 900-950°C which is a roughing delivery temperature (RDT); and a step of cooling and coiling the hot-rolled steel.</p> |
