| 摘要 |
PURPOSE: A steel product for a welding structure is provided which has superior toughness in a heat-affected zone as a difference between a base metal and the heat-affected zone is being minimized even in the weld heat input ranging from middle heat input to very large heat input using TiN and TiO oxides, and a method for manufacturing the same and a welding structure using the same are provided. CONSTITUTION: The method for manufacturing a steel product for a welding structure having superior toughness in a heat-affected zone comprises the processes of heating a steel slab in the temperature range of 1100 to 1250 deg.C for 60 to 180 minutes, a composition of the steel slab comprises 0.03 to 0.17 wt.% of C, 0.01 to 0.5 wt.% of Si, 0.4 to 2.0 wt.% of Mn, 0.005 to 0.2 wt.% of Ti, 0.0005 to 0.1 wt.% of Al, 0.008 to 0.030 wt.% of N, 0.0003 to 0.01 wt.% of B, 0.001 to 0.2 wt.% of W, 0.03 wt.% or less of P, 0.03 wt.% or less of S, 0.002 to 0.03 wt.% of O and a balance of Fe and other impurities, wherein 1.2<=Ti/N<=2.5, 10<=N/B<=40, 2.5<=Al/N<=7, 6.5<=(Ti+2Al+4B)/N<=14, 4 <=Ti/O<=10; hot rolling the heated steel slab at a 40% or more of rolling ratio in the austenite recrystallization temperature zone; and cooling the hot rolled steel slab to a finishing temperature of ferrite transformation±10 deg.C in a cooling rate of 1 deg.C/min or more.
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