Study On The Microstructure And Properties Of 42CrMo4 With Different Tempering Process

As a new type of high-strength alloy steel,42CrMo4 steel is widely used in large-bearing manufacturing in various fields.To explore the optimal tempering process,improve the microstructure and mechanical properties of 42CrMo4 steel as the experimental object,and study the microstructure and property changes under the heat treatment process of different tempering temperatures and holding time;The tempering process was simulated by finite element method to analyze the variation of residual stress with tempering temperature,and the residual stress was detected by X-ray diffraction method to verify the simulation results.The influence of thermal deformation parameters on the flow stress of 42CrMo4 steel with optimal heat treatment was analyzed by thermal compression experiments.The constitutive model and hot processing map of the alloy steel are constructed to provide theoretical guidance for hot working.The following research results were obtained:（1）Through the heat treatment experiment,determine the optimal heat treatment system of 42CrMo4 steel:600℃tempering insulation for 3h.（2）Through the tempering process of 42CrMo4 steel simulation,obtained the residual stress change law:with the tempering temperature increases,the stress gradually decreases.（3）The hyperbolic sinusoidal constitutive model of 42CrMo4 steel is established through the analysis of the experimental data of hot compression.The results show that the thermal activation energy Q=395.98KJ/mol and the stress index n=6.59588.（4）The hot processing map of 42CrMo4 steel is drawn when the strain variable is0.1,0.3,and 0.5.According to the hot processing map,it is found that when the strain variable is 0.1,the processing stability is better at high temperatures and high strain rates.When the strain variable is 0.3,the deformation condition of 700-740℃and0.007-0.4s^-1should be avoided during processing.When the strain is 0.5,there is no instability zone.