Numerical Simulation And Experimental Study On Deformation Process Of ZK60 Magnesium Alloy By ECAP Deformation And Secondary Extrusion

As the lightest commercial structural metal,magnesium alloy has great potential in the biomedical,aerospace and automotive industries.However,since the magnesium alloy is a hexagonal closed-packed crystal structure,the formability is poor,and the room temperature strength is low,which limits its industrial application.The Equal-Channel Angular Pressing?ECAP?process can refine grains by large strain distribution,but the strain distribution is not uniform.Therefore,improving the uniformity of workpiece deformation after ECAP process deformation has important research significance for improving the microstructure and mechanical properties of the workpiece.Secondary extrusion can effectively improve the uniformity of workpiece deformation.The research on secondary extrusion process of magnesium alloy has great practical significance.If the secondary extrusion process is only experimentally studied and the cost is high,and the deformation process is complicated,it is difficult to obtain the distribution of various fields during the processing.Therefore,it is necessary to apply the finite element method to study the secondary extrusion process in order to simulate and analyze the mechanism and law of microstructure evolution during secondary extrusion deformation.This study mainly uses DEFORM^TM-3D software to simulate the deformation process of ZK60 magnesium alloy by ECAP deformation and secondary extrusion.Due to the poor plasticity of the cast magnesium alloy,cracks are easily generated during ECAP deformation.Therefore,the extruded ZK60 magnesium alloy is used as the raw material to make the material easier to shape during the deformation process.The microstructure changes of magnesium alloy during ECAP deformation and secondary extrusion deformation were analyzed.The optimal parameters of extrusion process were designed and determined,and corresponding experiments were carried out to verify.The numerical simulation software DEFORM^TM-3D was used to simulate the single pass ECAP deformation and secondary extrusion process of ZK60magnesium alloy.The effects of ECAP deformation and secondary extrusion on load-stroke,strain field and strain uniformity at different temperatures were simulated and analyzed.At the same time,the tissue simulation of ECAP and secondary extrusion was carried out,and the dynamic process of grain structure before and after secondary extrusion was obtained.In order to verify the simulation results,the metallographic structure analysis and hardness test of the extruded ZK60 magnesium alloy,one-time ECAP and the secondary extrusion deformation extrusion were carried out,and the microstructure change law during the deformation process was studied.The microstructure evolution of the experimental sample and the numerical simulation sample on the deformation zone is basically the same.The experimental results are in good agreement with the simulation results,indicating the significance of numerical simulation to guide the experiment.