The influence of die structure on the extrusion ability of AZ91 magnesium alloy

With higher strength and better flowing ability,AZ91 magnesium alloy is used as cast alloy commonly.It is necessary to determine appropriate extrusion temperature,extrusion speed and die structure for improving the plastic properties of AZ91 and developing new wrought magnesium alloy with higher strength.In this paper,the stress-strain relationship of the AZ91 magnesium alloy is investigated by thermal simulation test,and the suitable deformation temperature is determined.Based on the stress-strain relationship,the influence of the extrusion speed and die structure on the thermal field,velocity field and stress field are analyzed by FEM.The results show that,when the bearing length of tapered and streamline die is 15mm~20mm,a smooth surface and flawless magnesium alloy rod can be obtained with 5mm/s extrusion speed.When the bearing length of flat die is 10mm~20mm,the extrusion speed can reach 2.5mm/s to obtain high surface quality.The extrusion experiment of AZ91 magnesium alloy is carried out adopting 650T horizontal extruder,and the experimental results is in agreement with the FEM results.