Simulation And Optimization Of Multi-directional Extrusion Process For Square Three-way Of High-strength Magnesium Alloy

Magnesium alloys are widely used in aviation and aerospace industries due to their light weight and high specific strength.Magnesium alloy extruded parts have high precision,good performance,light weight and high specific strength,so they have a wide range of application prospects.Multi-directional extrusion technology can form parts with complex shapes,and the product has a complete streamline structure,so it is the main manufacturing process for manufacturing high-performance multi-pass parts.This article mainly studies the high-strength Mg-Gd-Y-Zn-Zr magnesium alloy square tee multi-directional extrusion forming process.Through the hot compression experiment on the high-strength Mg-Gd-Y-Zn-Zr magnesium alloy,the stress and strain data of the material hot working are obtained,and the constitutive model of the material is established based on the experimental data,and the microstructure analysis of the compressed sample The microstructure recrystallization model was established,and the mathematical model obtained was embedded into the software using the secondary development interface of the finite element software Deform,and the material model was established for the simulation and optimization of the multidirectional extrusion process of high-strength magnesium alloy.Designed the multi-directional extrusion square tee forging drawing and blank shape,and formulated two multi-directional extrusion process plans: one-step method and twostep method.The one-step method is to use a die to extrude the billet into forgings in multiple directions at one time;the two-step method is divided into two stages.The first stage is to use the die to back-extrude the cylindrical billet into a cylindrical billet,and the second stage is to use The mold extrudes the cylindrical blank into a square shape and extrudes it into three-way parts in multiple directions.Use the secondary developed finite element software Deform to establish a finite element model,import the constitutive equation of magnesium alloy into the Deform software to establish a material model,perform numerical simulations on the two process schemes,analyze the forming process of forgings,and analyze the horizontal punch Prerelease position for design.The distribution law of equivalent strain,equivalent stress and the change law of extrusion force with stroke under the two schemes are analyzed;the distribution and evolution law of grain size and recrystallization volume fraction of forgings are analyzed,and comparative analysis is carried out.In the end,the equivalent strain and equivalent stress distribution of the two-step method for forgings are uniform,the required extrusion force is small,and the average size of recrystallized grains is also small.The finite element simulation of the multi-directional extrusion process under different process conditions is carried out,and the equivalent strain,equivalent stress,extrusion force,grain size and re-emission of the forging at different temperatures,different extrusion speeds and different friction coefficients are analyzed.Crystal volume fraction distribution and evolution law.The response surface(RSM)approximate model was established with Isight software,and the shape of the cylindrical part formed in the first stage of the two-step method was optimized for multi-objective optimization.Finally,the strain distribution of the square three-way forging was more uniform and the extrusion force was reduced.