Numerical simulation of backward extrusion AZ80 magnesium alloy thick-walled pipe was carried out by using Deform-3 Dsoftware.The influence of extrusion temperature and extrusion speed on the forming process of backward extrusion was simulated and analyzed.The results reveal that the equivalent strain of the reverse extrusion process is mainly concentrated on the contact position between the punch and blank as well as on the pipe wall.The damage value of the inner wall and the outer wall of the pipe exhibits serious

and it is easy to cause damage.With increasing in the extrusion temperature

the temperature difference

equivalent stress and extrusion load of the tube forming are decreased

so the extrusion deformation is more uniform.With decreasing in the extrusion speed

the peak value of the metal flow rate is decreased

and the metal flow is more uniform with the decrease of the tube temperature difference

so the extrusion deformation presents more unifrom.The reliability of the simulated results is verified by the backward extrusion test of the magnesium alloy tube.