| 摘要 |
<p>Disclosed are a steel sheet for a line pipe having excellent resistance to hydrogen induced cracking and low temperature toughness and high strength by controlling an alloying element, and a process condition and a method for manufacturing the steel sheet for a line pipe. According to the present invention, the method for manufacturing the steel sheet for a line pipe manufactures a steel sheet which consists of: 0.05 to 0.10 wt% of carbon (C), 0.15 to 0.25 wt% of silicon (Si), 1.2 to 1.5 wt% of manganese (Mn), 0.01 wt% or less of phosphorous (P), 0.001 wt% or less of sulfur (S), 0.02 to 0.04 wt% of soluble aluminum (S_Al), 0.1 to 0.4 wt% of copper (Cu), 0.02 to 0.04 wt% of niobium (Nb); 0.1 to 0.2 wt% of chrome (Cr), 0.1 to 0.3 wt% of nickel (Ni), 0.005 to 0.015 wt% of titanium (Ti), 0.03 to 0.06 wt% of vanadium (V), 0.02 to 0.04 wt% of molybdenum (Mo), 0.0001 to 0.0020 wt% of calcium (Ca), remainder iron (Fe) and inevitable impurities. The final micro-structure has a composition structure containing acicular ferrite, polygonal ferrite, and bainite. The steel sheet for a line pipe has a toughness strength (TS) of 535 to 760 MPa, a yield point of 450 to 600 MPa, and a yield ratio of 93% or less.</p> |
