Study On Grain Evolution And Numerical Simulation Of 4130 Steel Valve Body In Multi-directional Die Forging Process

Further large-scale exploitation of oil and gas energy is the top priority in solving the current energy problem.As an important connector of drilling equipment,the valve body is widely used in the oil and gas industry.With the needs of oil and gas exploitation,valve bodies are used more and more under various complex conditions such as high temperature,deep cold,and high pressure.The working environment is very harsh,so its performance requirements are higher.The valve body using 4130 steel as the material is often due to the difficulty of the forging process during the hot working process,which leads to a variety of structural defects such as mixed crystal and coarse crystal in the manufacturing process,which affects its forming quality and use performance.Therefore,studying the high-temperature deformation behavior of the valve body material and the evolution of the microscopic grain structure during the deformation process has very important engineering significance for formulating,optimizing,and quantitatively evaluating the valve body forming process.In this paper,4130 steel is selected as the research object.Through the thermal simulation compression test,the flow stress curve under the deformation temperature of850?1250?,strain rate of 0.01?5s^-1,and strain amount of 0.6 is obtained,and friction is performed on it.Correction and temperature correction have resulted in a relatively accurate flow stress curve.Based on the revised curve,the influence of different thermal deformation process parameters on the flow stress of 4130 steel was analyzed,and the prediction model of the peak stress of 4130 steel and the thermal deformation constitutive equation considering strain compensation were established.By analyzing the metallographic photos of the sample after hot compression of 4130steel,the influence of different hot deformation process parameters on the micro-grain structure was studied,and the peak strain model,dynamic recrystallization critical strain model,and dynamic recrystallization dynamics of 4130 steel were established.Scientific model and related grain size model.Based on the dynamic material model theory and the Prasad instability criterion,the thermal processing diagram of the material was drawn,and the optimal thermal processing process window for 4130 steel was determined.Through the secondary development of DEFORM software,the macro and micro numerical simulation of the multi-directional die forging forming process of 4130 steel valve body was carried out.Combined with the deformation characteristics of the valve body forgings at different locations,the reasons for the formation of the grain structure in this location area are analyzed.Based on the grain size data of the valve body in this article,a reasonable method for evaluating the uniformity of the grain structure of valve body forgings is given.