| 摘要 |
<p>A non-heat-treated ferritic-bainitic steel to be used as hot-forged, wherein the following relation holds between the bainitic structure fraction f and the carbon content C(%): 1.4C + 0.4 ≥ f ≥ 1.4C in the metal structure after hot forging a steel material containing the following elements on the weight basis: C: 0.10∩0.35 %; Si: 0.15∩2.00 %; Mn: 0.40∩2.00 %; S: 0.03∩0.10 %; Al: 0.0005∩0.05 %; Ti: 0.003∩0.05 %; N: 0.0020∩0.0070 %; V: 0.30∩0.70 % and further containing at least one of Cr, Mo, Nb, Pb and Ca in a specified amount and cooling the forged steel to room temperature. It is possible to produce a non-heat-treated hot-forging steel having high tensile strength, fatigue strength and machinability.</p> |
