Study On Dynamic Recrystallization Behavior And Thermoplastic Flow Stress Of 42CrMo Steel

The purpose of the thermal deformation of materials is forming and modification. For many forgings, the proportion of modification is great.However, how to modifcate is with the deformation process and the deformation process parameters. Through the research and the control of forgings process parameters,We realize the modification of forging products and the organization's control, and eventually provide basis theoretical for the practical production. 42CrMo steel is common steel, high strength, with its quench-hardening ability and good toughness.It is mainly used to produce higher requirements and conditioning section of forgings,such as large fan, with big gear locomotives, crankshaft etc. This paper mainly studies 42CrMo steel. Through the quantitative research on plastic deformation behavior and dynamic recrystallization of 42CrMo steel. The author analyzed the influence of deformation process parameters on 42CrMo steel heat flow stress and dynamic recrystallization and established rheological model and dynamic recrystallization model.Finally,this research achievements of the paper provide theoretical references for modification of 42CrMo steel forgings.The main research work includes:①The author made hot compression experiment of 42CrMo steel specimen on Gleeble - 1500 hot simulator. The author studies 42CrMo steel stress-strain relationship in hot compressive deformation condition and analysis the influence of deformation process parameters on 42CrMo steel heat flow stress using experiment data.②The constitutive model of 42CrMo steel in hot deformation was established.This paper established the constitutive model of 42CrMo steel in experimental conditions range by regression analysis based on hot compression experiment results.This model mainly includes: Peak flow stress model, Fields-Backofen model and a correction model including a softening factor.③The analysis of dynamic recrystallization and experimental research. This paper established the dynamic recrystallization model of 42CrMo steel using data based on hot compression experiment results.This model mainly includes: The dynamic recrystallization kinetics model, the dynamic recrystallization kinematics model ,dynamic recrystallization grain size model.④We concluded that influence regularity of microstructure on deformation process parameters through the metallurgical microstructure observation of 42CrMo steel, The author analyzes the influence of process parameters on dynamic recrystallization critical strain value, the dynamic recrystallization scores and dynamic recrystallization grain size.⑤The various grain models were loaded into the finite element simulation software Deform-3D to simulate the hot forming tests.The research work of this paper has the vital significance on the modification of forging products and the control of forging organization and provide theoretical basis for the practical production.