Dynamic Continuous Cooling Transformation Diagram of 42CrMoA Steel

The critical transition temperature Acl,Ac3 and Ms of 42CrMoA steel were determined by Gleeble-1500D thermal simulation testing machine using dilatometric method combining with metallographic-hardness method.The inflation curve and phase transition point of the steel in the different cooling speed of continuous cooling after deformation was determined.The product microstructure morphology of cold austenitic transformation was analyzed.the Vickers-hardness at different cooling rates of these products was measured.The dynamic CCT diagram was obtained.The results show that the products of austenite transform are ferrite and pearlite when the cooling rate is lower than 0.1 ℃/s.Those would be ferrite,pearlite and bainite when the cooling rate is in the range of 0.2 to 0.5 ℃/s.Those would be ferrite,pearlite,bainite and martensite when the cooling rate is in the range of 0.6 to 0.7℃/s.Those would be bainite and martensite when the cooling rate is in the range of 1 to 15℃/s and those would be total martensite if the cooling rate is higher than 20℃/s.