| 摘要 |
PURPOSE: A method for manufacturing hot forged article is provided, which is capable of improving mechanical performance of automobile parts without execution of a separate heat treatment process after hot forging, and the forged article manufactured by the method are provided. CONSTITUTION: In a method for manufacturing forged article using carbon steel comprising carbon, silicon, manganese, phosphorus and sulfur, the method for manufacturing hot forged article having high strength and high toughness comprises the processes of hot forging low carbon steel comprising 0.10 to 0.15 wt.% of carbon(C), 0.15 to 0.35 wt.% of silicon(Si), 0.60 to 0.90 wt.% of manganese(Mn), 0.030 wt.% or less of phosphorus(P), 0.035 wt.% or less of sulfur(S), 0.6 to 1.0 wt.% of molybdenum(Mo), 0.08 to 0.15 wt.% of vanadium(V), 0.02 to 0.04 wt.% of niobium(Nb) and a balance of Fe and other inevitable impurities; and manufacturing a hot forged article in which bainite structure is contained in martensite matrix structure by rapidly cooling the hot forged low carbon steel. In a hot forged article containing carbon, silicon, manganese, phosphorus and sulfur, the hot forged article having high strength and high toughness is characterized in that it is formed of low carbon steel comprising 0.10 to 0.15 wt.% of carbon(C), 0.15 to 0.35 wt.% of silicon(Si), 0.60 to 0.90 wt.% of manganese(Mn), 0.030 wt.% or less of phosphorus(P), 0.035 wt.% or less of sulfur(S), 0.6 to 1.0 wt.% of molybdenum(Mo), 0.08 to 0.15 wt.% of vanadium(V), 0.02 to 0.04 wt.% of niobium(Nb) and a balance of Fe and other inevitable impurities, wherein 10 to 20% of fraction of bainite structure is contained in martensite matrix structure, and the hot forged article has 900 MPa or more of tensile strength and 70 J or more of toughness.
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