Effects of pre-treatment conditions on warm hydroformability of 7075 aluminum tubes

Warm hydroformability of 7075 tube materials was studied by hydroforming experiments between room temperature and 300 °C. Warm tension test was also performed to investigate the characteristics of the warm hydroforming process of high strength aluminum alloys. Especially, the effects of pre-treatment conditions on the flow behavior and the microstructures during warm deformation of tube materials were qualitatively analyzed. The results showed that sufficient elongation properties of high strength aluminum alloys, which are necessary for successful hydroforming of complex shaped parts in a single operation, could be achieved by the selection of pertinent pre-treatment conditions and deformation temperatures for hydroforming. It was shown that the flow behavior of 7075 was mainly affected by interplay of dynamic strain aging, dynamic recovery and dynamic precipitation according to deformation temperature.