Study On Warm Forming Technology Of AZ80 Magnesium Alloy Car Hub

In order to get a new method,new material to make the hub and achieve the goal of improving the quality of product,reducing the cost and energy consumption, select wrought magnesium alloy as the research subjects in this thesis and carry out research as follows:First, rheological property of AZ80 is studied applying Gleeble-3800 thermal-mechanical simulator. The emphasis is the influence of deforming temperature, deforming rate, and deforming amount on deformation resistance of material, from which the law is found. The mathematic model of peak value of this material is set up according to regressive method, which provided deformation activation energy of magnesium alloy, basic gist for choosing technological parameter of isothermal extrusion formation.Secondly,adopting isothermal plane strain experiment ,the influence on the law of deformation and strength-toughening of AZ80 magnesium alloy are studied according to deformation degree and deformation temperature. The result indicated that the deformation effect is conspicuous at 200～250℃, the deformation degree of tensile strength is approximately linear increased, the reason of which is preserving a significant deformation strengthening effect after deformation. While the deformation temperature is more than 300℃, the deformation reach a certain degree, tensile strength is tend to be stabilized because of dynamic recrystallization. Based on the experiment condition tensile strength improve in various degree which increased by more than one time before homogenizing treatment, elongation also improved than cast state.Based on the experimental results, the influence law on the structure of two punches: core shaft,no core shaft is analyzed applying FEM in allusion to isothermal extrusion forming of AZ80 magnesium alloy car wheel. The influence on equivalent stress and pressure during deformation is discussed by different core shaft diameter and inner diameter of blank-billet. At last the forming method:"blank-billet, core shaft extrusion"is presented.From the thermal simulation,isothermal compression and computer simulation results, the forming parameters of AZ80 magnesium alloy are determined which provided theoretical foundation for plastic forming. We constituted forming processing routes:cast ingot--homogenizing treatment--cutting stock--upsetting--backward extrusion--upsetting-extruding front wheel-flange--expanding-flanging rear wheel-flange--next processing. Experimental verification has been conducted.The experimental results show that the forming force is small according to the new method, and the constituted process and the die designed are reasonable and feasible, and the mechanical property, microscopic structure and size accuracy of the forming accessory are all satisfactory, which provided theory and practical gist for plastic forming of the accessories with holes at the bottom.