Numerical Simulation And Experimental Study Of Cold Drawing Of Magnesium And Magnesium Alloys Based On Deform-3D

Due to their low density,magnesium and magnesium alloys have high specific stiffness and specific strength.At the same time their good thermal conductivity,electromagnetic shielding performance and vibration damping behaviour make them have a broad prospect in industrial application.Magnesium has poor plasticity in room temperature because of its close-packed hexagonal structure,therefore it’s difficult to be cold plastic forming.Currently magnesium and magnesium alloy have been plastic deformed by the technology of multiple-pass wire cold drawing.It’s has a profound significance for promoting the diversity of the deformation mode and expanding the application field.With the two ways of numerical simulation based on Deform-3D and experimental study,φ 1.897mm AZ31,Mg2Zn and pure magnesium wires have been got by the multiple-pass wire cold drawing with small deformation per pass.On this basis,the influence factors of drawing force,the metal flow characteristics of magnesium wire,effective strain and regularities of residual stress distribution have been studied by numerical simulation.In addition,the evolutions of microstructure and mechanical properties during the multiple-pass wire cold drawing also have been studied by experimental study.The main results are as follows:During the process of cold drawing deformation,the drawing force is affected by the coefficient of friction,semi-cone angle of mould,and the drawing speed.In addition to extension deformation in the process of deformation,the surface of the metal also has the shear and bending deformation.From the center to the surface,the effective strain of φ1.8 97mm AZ31,Mg2Zn and pure magnesium wires is all on the rise trend.The deformation difference on the cross-section of AZ31 magnesium alloy wires is the largest,while pure magnesium is the least.Introduce the strain standard deviation θ to measure the magnesium wires’deformation uniformity.When drawing pass increases,the strain standard deviation of three components wires increases.Under the same cumulative deformation,decrease the drawing pass,increase the single channel of deformation degree,θ value will be reduced when the drawing pass decreses and deformation of each pass increases.AZ31,Mg2Zn and pure magnesium wires’residual stress from the axial,circumferential and radial gradiently distributes.From the center to the surface,the residual stress distribution of AZ31 magnesium alloy wires is the largest,while pure magnesium is the least.The axial residual stresses on the surface of three components of φ1.897mm wires measured by numerical simulation approximate to numerical value measured by X ray diffraction detection experiments.It indicate that the finite element model of wire multi-pass cold drawing process established by Deform-3D is verified.Under the same cumulative deformation,decrease the drawing pass can reduce the residual stress.During the cold drawing process of AZ31,Mg2Zn and pure magnesium wires,when the cumulative strain is small,the main deformation mechanism of twining.When the cumulative deformation is bigger,slipping and twining coexistence.The final deformation mechanism is mainly the slipping.Microstructure of fine grain can be got,the grain of AZ31 magnesium alloy is smallest,while pure magnesium is the biggest.With the increase of accumulative deformation,the microhardness and tensile strength of AZ31,Mg2Zn alloys are increased with the increase of accumulative deformation degree on the rise of the trend,While the changing process of microhardness and tensile strength of pure magnesium is mainly divided into two phases,They significant increase in the first stage.In the second stage,with the increase of accumulative deformation,the microhardness and tensile strength decline.In addition,due to the formation of the texture in the process of cold drawing,the cross section and vertical section of hardness are different.