| 摘要 |
PURPOSE: A steel material for a high strength structure and a manufacturing method thereof are provided to obtain the precipitation strengthening effect by increasing the content of titanium, vanadium, and nitrogen, thereby securing more than 750MP of tensile strength. CONSTITUTION: A steel material for a high strength structure manufacturing method comprises the following steps: reheating(S110) a steel slab, hot-rolling(S120) the reheated steel material at 950-1000°C for finishing rolling, and cooling(S130) the hot-rolled steel material at below -5°C/sec of the average cooling rate. The steel material comprises, in wt %: C 0.17-0.20, Si 0.25-0.45, Mn 1.25-1.40 of Mn, P less than 0.015, S less than 0.005, Ni 0.1-0.2, V 0.28-0.32, Ti 0.05-0.08, Al 0.01-0.02, Nb 0.04-0.05, N 0.01-0.015 and other unavoidable impurities including Fe. The steel material additionally includes more than one component of less than 0.1wt % of Cr and less than 0.15wt % of Cu. [Reference numerals] (AA) Start; (BB) End; (S110) Reheating slab(SRT:1150-1250°C); (S120) Hot rolling(FDT:950-1000°C); (S130) Cooling(air cooling) |
