Mold And Process Design For The Superplastic Forming Of Magnesium Based On The Numerical Simulation

As the lightest metal structure materials, magnesium alloy has many advantages such as high specific strength and stiffness, excellent machinability, good recyclability, nice vibration dampening property and so on, thus, it attracts more and more attention with the increasing demand for energy conservation and it is widely applied to aerospace, transportation, telecommunications, etc. Due to hexagonal crystal structure, magnesium alloys have relatively low workability at room temperature. At present, the majority of magnesium components are manufactured by casting process, especially die casting. However, the mechanical properties of the cast magnesium alloy are weak because of the defects of this process (e.g. shrinkage cavity, shrinkage and slag) and this restricts the application of magnesium alloy greatly. Meanwhile, as one kind of the plastic deformations, super plastic deformation not only overcome the defects of casting, but also can produce complex parts by one-off and decrease the amount of post-processing and accordingly achieve high utilization of material. However, there is less research on superplastic forming of magnesium alloys from home and abroad..In this paper, two sets of mold for superplastic forming of two complicated parts were designed based on the deformation resistance of AZ80 magnesium alloy in plastic forming process obtained by theoretical calculation at first and the 3D models of the two sets of mold were established by Solidworks software. Then the numerical simulations of the forming processes of the two parts were analyzed under different temperatures (35℃、 375℃、400℃)and different loading rates(10mm/min、8mm/min、6mm/mn、4mm/min、 2mm/mi民、1mm/min) through DEFORM—3D software. The numerical simulation of the forming process of each part came in three stages. The reasonable forming solution of each part and appropriate process parameters were obtained through the first stage of numerical simulation. The stress and strain of each set of mold during the forming process was obtained through the second stage of numerical simulation under the appropriate process parameters, the analysis on the velocity field, equivalent stress field, plastic flow direction and the relationship between load and stroke were also carried out during this period. The mold structure of each part was optimized based on the results of the second stage simulation. The third stage of numerical simulation was carried out to check the strength and stiffness of the optimized mold and the result showed that the mold that optimized also met the requirement for the strength and stiffness. Finally, the reasonableness of the die design and accuracy of numerical simulation were verified through the test.