Experimental Study And Numerical Simulation Of Hot Deformation Behaviors Of AZ40Alloy

Magnesium alloys is considered to be the most promising engineering materials,because of its many excellent properties The special crystal structure make it difficult toproduce plastic deformation at room temprerature, and in the high temprerature it is easy toproduce coarse grain and surface oxidation.At present, the vast majority of magnesiumproducts are die-casting products,and there are very few products by plasticprocessing.There are more advantages of plastic processing than die casting such as fineand uniform grains, without defect such as pore-free and crackle etc and better mechanicalproperties. In order to study the characteristics of warm forming process for magnesiumalloy,this paper begins with the forming property of AZ40magnesium alloy at hightemperature.The stress model and the microstructure evolution model of magnesium alloyAZ40are developed by the hot compress test. Numerical simulation of the axis part with asquare hole on the end extrusion process is carried out by using the software DEFORM-3Dwhich combined with the establlished model and the thermal-machanical coupled finiteelement method. Analyse the influences of process for AZ40magnesium alloy andguidance to optimize the hot forging process of magnesium alloys parts with complicatedshape.In this paper, AZ40magnesium alloy flow stress-stain curves in the temperature rangeof warm forging have been determined by the experiment of hot deformation. Equationbetween stress-stain and Zener-Hollomon was deduced based on the experimental data,andthe stress model has been set up.According to the quantitative matallography,the grain size of AZ40magnesium alloycan be measured under the different deformation conditions.So the relatiionship betweenthe size of dynamic recrystallization grain and Zener-Hollomon is established by themeasurement data.The Micro-hardness values of AZ40magnesium alloy under thedifferent deformation conditions were measured,equation between Micro-hardness andrecrystallization grain size is established by the measurement data.The aim of thisexperiment was to create microstructure evolution model and micro-hardness model.Absoft fortran language was secondarily used to develop DEFORM-3D software,which combined with the stress model and the microstructure evolution model.Based onthe new DEFORM-3D, the numeerical method of thermal-mechanical coupling for the axis part with a square hole on the end extrusion process is presented.The influences ofdeformation temperature and defromation rate on the flow stress,strain,and grain size wereanalyzed during the axis part with a square hole on the end hot extrusion.