| 摘要 |
<p>The present invention relates to a high tensile steel having a tensile strength (TS) of 500-700 MPa, a yield point (YP) of 400-550 MPa, a transition temperature of -50 to -70°C by designing an alloy based on low Ceq., rolling under the conditions of the low slab reheating temperature and heavy deformation, and controlling so that properties of matter of the center part is not deteriorated under a condition of spray cooling, and to a manufacturing method thereof. According to the present invention, the method for manufacturing the high tensile steel includes: (a) a step of reheating a slab at a slab plate reheating temperature of 1000-1050°C, wherein the slab includes: 0.05-0.1 wt% of carbon (C), 0.2-0.3 wt% of silicon (Si), 0.9-1.6 wt% of manganese (Mn), 0.01 wt% or less of phosphorous (P), 0.005 wt% or less of sulfur (S), 0.015-0.05 wt% of aluminum (Al), 0.2-0.6 wt% of nickel (Ni), 0.1-0.3 wt% of copper (Cu), 0.01-0.03 wt% of niobium (Nb), 0.01-0.02 wt% of titanium (Ti), 5-50 ppm of calcium (Ca), and the remainder consisting of iron (Fe) and inevitable impurities; (b) a step of hot-rolling the reheated slab; and (c) a step of cooling the hot-rolled slab at a finish cooling temperature of 300-400°C.</p> |
