| 摘要 |
<p>Disclosed are a steel sheet for a line pipe with high strength and excellent DWTT performance through alloying constituent control and process condition control, and a manufacturing method thereof. According to the present invention, the method to manufacture a steel sheet for a line pipe comprises: (a) a step of reheating, at a temperature of 1050-1150°C, a slab plate including 0.05-0.08 wt% of carbon (C), 0.2-0.3 wt% of silicon (Si), 1.7-1.9 wt% of manganese (Mn), 0.012 wt% or less of phosphorous (P), 0.0012 wt% or less of sulfur (S), 0.05 wt% or less of aluminum (Al), 0.02-0.04 wt% of niobium (Nb), 0.015-0.025 wt% of titanium (Ti), 0.04-0.06 wt% of vanadium (V), 0.0005 wt% or less of boron (B), 0.2-0.3 wt% of molybdenum (Mo), 0.2-0.3 wt% of nickel (Ni), 0.15-0.25 wt% of copper (Cu), 0.1-0.2 wt% of chrome (Cr), 0.003wt% or less of calcium (Ca), and the remainder consisting of iron (Fe) and inevitable impurities; (b) a step of primarily rolling the reheated plate in a recrystallization area of austenite; (c) a step of secondarily rolling the primarily rolled plate in a non-recrystallization area under a condition of finish rolling temperature of Ar3-50 to Ar3°C; and (d) a step of cooling the secondarily rolled plate.</p> |
