| 摘要 |
<p>PURPOSE: A structural steel having high-strength due to the addition of trace alloying elements and a manufacturing method thereof are provided to control Al, V, and N content and a cooling condition subsequent to a hot rolling without a controlled rolling, thereby securing an yield strength of more than 450 MPa(megapascals) and an impact value of more than 100 J(joule). CONSTITUTION: A structural steel having high-strength comprises 0.14 to 0.16 wt% of C, 0.25 to 0.35 wt% of Si, 1.25 to 1.35 wt% of Mn, less than 0.03 wt% of P, less than 0.015 wt% of S, 0.1 to 0.15 wt% of Ni, 0.07 to 0.15 wt% of Cr, 0.15 to 0.2 wt% of Cu, 0.04 to 0.06 wt% of V, 0.04 to 0.06 wt% of Al, less than 0.008 to 0.012 wt% of N, remnant Fe and other inevitable impurities. The yield strength of the steel is more than 450 MPa. The impact value of the steel is more than 100 J at a temperature of -5 Celsius degrees. A manufacturing method of the structural steel having a high-strength comprises: a step(S110) of reheating a slab steel; a step(S120) of hot-rolling the steel; and a step(S130) cooling the steel. [Reference numerals] (AA) Start; (BB) End; (S110) Slab reheating step; (S120) Rolling step; (S130) Cooling step(air-cooling)</p> |
