The microstructure,strength,toughness and fatigue properties of an ultra-high strength steel 40CrMnSiMoVA have been investigated.The so-called meta-bainite,composed of thin re- tained austenite films within or between...The microstructure,strength,toughness and fatigue properties of an ultra-high strength steel 40CrMnSiMoVA have been investigated.The so-called meta-bainite,composed of thin re- tained austenite films within or between the bainitic ferrite lathes was found in the steel after isothermally quenched at 300℃ for 1h.In comparison with the martensite structure obtained by isothermally quenching in martensite range,the meta-bainite has more excellent strength and plasticity,lower notch sensitivity,stronger strain harden ability,higher fatigue strength, longer strain or impact fatigue life,slower crack propagation rate and more remarkable overload effect on increasing fatigue life.展开更多
CCT-diagrams of Si-Mn-Mo bainitic steels have been determined.With Mo 0.25%,the high-temperature transformation of the steel shifts large to the right,and the bainitic trans- formation region becomes a“flat topped C-...CCT-diagrams of Si-Mn-Mo bainitic steels have been determined.With Mo 0.25%,the high-temperature transformation of the steel shifts large to the right,and the bainitic trans- formation region becomes a“flat topped C-curve”at cooling rate in wide range.Si in the steel may cause shift of the bainitic transformation region towards the right,and of the pro-eutectoid ferritic transformation region towards the left.Mn may delay the high temper- ature transformation more violently than the bainitic transformation.展开更多
文摘The microstructure,strength,toughness and fatigue properties of an ultra-high strength steel 40CrMnSiMoVA have been investigated.The so-called meta-bainite,composed of thin re- tained austenite films within or between the bainitic ferrite lathes was found in the steel after isothermally quenched at 300℃ for 1h.In comparison with the martensite structure obtained by isothermally quenching in martensite range,the meta-bainite has more excellent strength and plasticity,lower notch sensitivity,stronger strain harden ability,higher fatigue strength, longer strain or impact fatigue life,slower crack propagation rate and more remarkable overload effect on increasing fatigue life.
文摘CCT-diagrams of Si-Mn-Mo bainitic steels have been determined.With Mo 0.25%,the high-temperature transformation of the steel shifts large to the right,and the bainitic trans- formation region becomes a“flat topped C-curve”at cooling rate in wide range.Si in the steel may cause shift of the bainitic transformation region towards the right,and of the pro-eutectoid ferritic transformation region towards the left.Mn may delay the high temper- ature transformation more violently than the bainitic transformation.
