Simulation Of Phase Transformation And Microstructure Of 38MnVTi Non-quenched Steel During Cooling

Today people have high requirements for environmental protection.Application of energy-saving steel is a trend.Non-tempered steel,is a steel that does not require quenching and tempering treatment,reduces production processes and energy consumption.38 MnVTi is a ferrite-pearlite non-quenched and tempered steel.38 MnVTi is mainly used to produce automobile engine connecting rod.It is important to control the cooling process behind the hot forming,because it does not need to be quenched and tempered.Computer technology can simulate the change of microstructure after thermal forming.At present,there are many studies on the numerical simulation and process optimization of microstructure evolution during the thermoplastic forming process of materials and many experimental studies on the phase transition in the cooling process after thermoforming.Therefore,the research of phase transformation during the cooling process after 38 MnVTi hot forming is very important for Chinese non quenched and tempered steel,which can optimize the workpieces performance,reduce the cost and shorten the production time.In this paper,a thermal simulator is used to complete the experiment.First,the critical point of 38 MnVTi is obtained by thermodilatometry.Then the thermal expansion curves of different isothermal temperatures are obtained.The final isothermal cooling curve can be obtained for computer simulation.The expansion curves of different cooling rates are obtained by thermodilatometry.Microstructures were observed through microscopes and scanning electron microscopy(SEM).The hardness of samples obtained at different cooling rates.Drawing the continuous cooling transition curve of 38 MnVTi.The transformation law of 38 MnVTi and the microstructure of the phase transition are analyzed.The analog result can be used to predict the experimental resultsIntroducing the obtained TTT curve into the Deform material library.Calculation of thermal physical parameters by reverse heat transfer.The cooling phase transition of 38 MnVTi was simulated by deform,and the microstructures of different cooling rates were obtained.The results of continuous cooling curve through simulation are drawn.The CCT curve obtained by the simulation and the CCT curve obtained by the experiment are compared,and the results are similar.The effect of stress on the continuous cooling transformation behavior of non quenched and tempered steel 38 MnVTi was studied by thermal deformation test.The continuous cooling expansion curves at different deformation temperatures,different deformation temperatures and strain rates were obtained.The phase transition of 38 MnVTi and the phase change products were analyzed for different deformation parameters through the metallographic photographs.