Research On Drawing Process And Structure And Properties Of Magnesium Alloy

In this paper,a kind of closed drawing device,with capacity of heating and temperature-controlling,and drawing die are designed.Extruding and drawing are used to form thin-walled WE43 magnesium alloy tubes ofΦ4.0mm×0.25mm and alternation rules of wall thickness of the tubes are discussed;drawing forces under different processing parameters are measured and effect of drawing processing parameter on drawing force is analyzed;effect of heat treatment on properties and structure of extruded WE43 magnesium is discussed,and impact of deformation degree on properties and structure of drawed WE43 magnesium alloy,as well as its deformation mechanics,is researched.The results show that drawing processing of magnesium alloy bars and tubes can be realized in the presence of drawing device and dies designed.Thin-walled magnesium alloy tubes ofΦ4.0mm×0.25mm formed through a series of crafts of extruding,drawing, machining and heat treatment have homogeneous wall thickness,good performance and structure and surface quality.Mechanical properties of the tubes can reach:σ_b＞200MPa,δ＞15%.Multi-pass drawing and decreasing elongation coefficient can reduce circumferential compressive stresses which tubes bears during drawing,prevent effectively increasing tendency of wall thickness,and are also favorable to homogeneous wall-thickness;T4 heat treatment can also prevent the increasing tendency of wall thickness.The bigger the Elongation coefficient,the bigger the drawing force needed;drawing force first decline and then increase with the increasing of drawing velocity.When v equals to 0.25mm/s,drawing force is lowest,making that optimization of drawing velocity is realized.Drawing processing of tubes designed is feasible,and assurance coefficient K of all passes is much greater than 1,making sure that no breaking occurs during drawing.Solution treatment can improve structure and properties of extruded WE43 magnesium alloy,and reduce probability of tubes overlapping during drawing.Through solution treatment of 525℃×8h,this alloy have excellent comprehensive properties in room temperature,rare-earth phases chang into fine particles and distribute homogeneously inα-matrix.Multi-pass drawing makes tensile strength of WE43 magnesium alloy increase and elongation decrease.Twin nucleation is main nucleation way of drawed magnesium alloy, and is favorable to recrystallization and refinement of magnesium alloy grains.When deformation degree is up to 84.2%,grain size reduces from 23μm to below 8μm.