The effect of forming temperature on the deep drawability (limit drawing ratio (LDR)) of AZ31 magnesium alloy sheet was studied both numerically and experimentally by the use of finite element analysis software DYNAFORM and specially designed warm deep drawing die set. The simulation model was built by SolidWorks 2009, 3-Parameter_Barlat model with BT shell unit was adopted as material model. The constitutive relation of the material was provided by uniaxial isothermal tension tests at different temperatures. After being set, all parameters were referred to famous explicit dynamic solver LS-DYNA. The simulation results showed that the LDR of the AZ31 magnesium alloy sheet is increased with the increase of the temperature initially, but after the temperature reached 423K, the LDR reached the maximum, and then decrease with the increase of temperature in the temperature range studied (room temperature-673K). PTEF was used as lubricant in the experiment. Experimental results showed same trend as numerical simulation results in the studied range of temperature, and LDR reached the maximum of 3.0 at 423K. It is shown that the results of numerical simulation have a good agreement with that of the experiment. By analyzing the microstructure of the drawn-cup walls at different temperatures, it is found that grains were stretched along the direction of tension at temperatures lower than 423K. And there appeared a large number of fine recrystallized grains when forming temperature is 423K showing that dynamic recrystallization occurred during forming process. Dynamic recrystallization conducted completely when forming temperature increased higher than 423K, but the material softening would aggravate with the increase of temperature and on the contrary would do harm to the deep drawing of AZ31 magnesium alloy sheet, resulting the decrease of LDR.
Finite Element Simulation of Warm Deep Drawing of AZ31 Magnesium Alloy Sheet
