The Effect Of Back Pressure On Superplastic Forming Performance Of AA5083 And Deformation On Mechanical Properties Of TC4

Superplastic pneumatic bulge forming is an important application of superplastic forming, which has been widely appied in the aeronautics, astronautics, shipping, automibiles, electronic communications and etc. However, it is still needed of futher research on the mechanisms, and application technologies of superplastic pneumatic bulge forming. Superplastic bulge experiment is considered to be the best way to investigate the superplastic forming performance of sheets.It is mainly researched on two sides in this paper:Firstly, finite element simulation is utilized to get the p-t curve for different forming ways, and then caviation and forming limits of the sheets which formed in different conditions are compared to investigate the effect of back pressure on the superplastic forming performance.Secondly, finite element simulation is utilized to get the p-t curve and then the superplastic bulge test is conducted. After that, the effects of deformation on condition fatigue strength, static strength, plasticity and the grain size of TC4 are evaluated.It is shown by the experiment that back pressure can effectively restrain the generating and growing of the caviation and then the forming limit of AA5083 aluminium alloy cone workpiece is improved. The bulging elongation of the vertex of the cone workpiece is 266% without back pressure while they increase to 324% under the condition of 1.5MPa back pressure and 567% under the condition of 3MPa back pressure. And that for the TC4 titanium cylinder parts, static strength declines when bulge elongation is less than 100% while strength limit and yield strength are keep constant proximately. Besides this, condition fatigue strength declines as the elongation increases.