Backward Extrusion Forming Technology Research Of Multilayer Shell Parts Of AZ80Magnesium Alloy

Magnesium and magnesium alloy has attracted more and more attention due to a series of advantages such as its low density, high specific stiffness, good damping capacity, process ability, excellent thermal conductivity, electromagnetic shielding and recyclability. They have been considered as eco-structural metal material in the21st century.The work which has been done in this paper is as follows:1. On analysis of the structure and shape characteristics of the AZ80magnesium alloy multilayer shell part, the forming process and forming force were determined, and so did to the extrusion methods and extrusion equipment. And the initial development of the extrusion solution was formulated.2. Using a numerical simulation analysis which was made on the extrusion and deformation process with the finite-element simulation software-MSC.Marc, the effects of the billet temperature, friction coefficient and the extrusion rate in deforming process were discussed and the law of influence on the extrusion force, stress, strain by different process parameters are acquired, thus the extrusion die and the extrusion parameters were optimized.3. The mold in the extrusion experiment was designed, and the AZ80magnesium alloy multilayer shell parts were extruded successfully in the laboratory and the law of influence on the forming quality and microstructure by different process parameters. The results show that the smaller of the billet diameter, the easier to eccentric during forming. When the mold had the same temperature, the performance would be increased at first and then declined with the billet temperature increasing. When the billet had the same temperature, the higher mold temperature, and the much better performance of the part after molding.4. The solution and aging treatment for the AZ80magnesium alloy multilayer shell parts were carried out. The experiment results show that:the solution treatment can improved the tensile strength and extensibility of mold and the part with lower billet temperature. For the multilayer shell parts with higher extrusion temperature, the solution treatment reduced the tensile strength and extensibility in contrary. The aging time had a great effect on the mechanical properties of the parts. With the increase of aging time, the number of the phase of β-Mg17Al12phase and the proportion of the precipitated phase gradually increased which lead to the increase gradually of the tensile strength and the decline significantly of the extensibility.