Study on continuous cooling transformation of dual phase steel with 0.06C-0.6Si-1.5Mn-0.6Cr

The continuous cooling transformation curves without and with deformation of a dual phase steel(0.06C-0.6Si-1.5Mn-0.6Cr) were studied by Gleeble-1500 thermal-mechanical simulation.Microstructures were observed by using an optical microscope and the hardness of the specimens was measured.The results showed that the volume fraction of bainite and Vickers hardness increased obviously with the cooling rate increasing when the cooling rate was lower than 10℃/s;while the volume fraction of bainite(both at undeformed and deformed states) and hardness tended to vary gently in the cooling rate range of 10~20℃/s.From CCT curves,it can be drawn that γ→α transformation temperature is between 780～550℃ for the deformed steel and bainite can be gained in the cooling rate of 2~20℃/s.