Simulation of Back-pressure Equal-channel Angular Pressing Deformation of AZ31 Magnesium Alloy with Different Extrusion Rates
Grain refinement is one of the key technologies to improve the strength and ductility of Mg alloys.The severe plastic deformation is often used as the preferred technique for grain refinement.The equal channel angular pressing(ECAP)is widely used because it can greatly refine the grains.However,the general ECAP process is difficult for further refining grains when the grains are refined to a certain extent,and it needs to be improved.Thus,a new type of back pressure equal channel angular pressing process was designed,and the process was simulated by using Deform 3D software,and the effects of different extrusion rates on the deformation process of AZ31 magnesium alloy were studied.The results show that setting back pressure in the process of equal channel angular extrusion can promote the equivalent strain,which is very sensitive to the strain rate.At low extrusion rate,the local metal flow and equivalent stress are significantly intensified.After reaching a certain level,the effect of back pressure on releasing stress concentration is obvious,and the local stress and strain increase is not obvious.This is mainly related to the deformation mechanism of magnesium alloy basal plane and prismatic non-basal slip.This new process plays an important role in further grain refinement and performance improvement of magnesium alloy materials.
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