Researches On Numerical Simulation And Experiment In Equal-Channel Angular Pressing Of ZK60Magnesium Alloy

Magnesium alloys have many advantages such as specific strength, specificstiffness, good thermal conductivity, ease of machining and facilitate to recycleand so on. They are widely used in aerospace, electronics, automotive industryand other fields. However, there are many unfavorable factors such as poorductility at room temperature, poor forming ability and so on in Mg alloys, whichseverely limit their wider application. Refining grains can make the material havenot only higher strength, but also better plasticity. Therefore, to study themethods of refining grains has great theoretical and practical significance.In recent years, as one of severe plastic deformation technology, ECAP iswidely used to obtain ultrafine-grained materials. This method can get moredistortion on the premise of basically not changing the shape of materials.Besides, it can ultimately form equiaxed fine grains with good mechanicalproperties by increasing extrusion passes to accumulate strain. Particularly, thetechnology used in this research is EX-ECAP with back-pressure, which there isa conventional hot extrusion prior to ECAP, and there is a plunch at the exit holeof channel to apply the material a force during the extrusion process. The methodcan not only effectively prevent sample cracking, but also avoid the defect of thedead zone.In this paper, there are mainly three aspects of studies on ECAP deformationprocess of ZK60magnesium alloy. Firstly, tensile test is conducted on the ECAPsamples under various tensile temperatures to study the mechanical properties ofECAP samples of multi-pass extrusion at different temperatures. Secondly, themetallurgical structure, fracture morphology and TEM structure of ECAP samples are observed. By discussing the organizational change during the deformationprocess we try to find out the deformation mechanism and the more optimalconditions.Finally, we use the DEFORM-3D FEM program to simulate theprocess of ECAP for different passes to analyse the change and distribution ofthese parameters such as velocity, stress, temperature and so on, and compare theresult of organizational simulation with the experimental result.