Description of stress-strain response and evaluation of the formability for Al-Cu-Mg alloy under the impact hydroforming

This study aims at investigating on the descriptions of stress-strain response and the assessment of formability for Al-Cu-Mg alloy under impact hydroforming (IHF). IHF process effectively combines the advantages of the flexible liquid and the impact impulse. The formability of low plastic materials can be increased by using IHF process. The elongation of Al-Cu-Mg alloy can even be more than 50 % compared with the quasi-static forming means (27 %∼30 %) if the strain rate was on the level of 5000/s. The stress-strain curve is characterized with S-shape. It is found that the strain hardening rate decreases linearly at the stage III, increases linearly at the stage IV and decreases non-linearly at the stage V. The deformation mechanism is the interaction of dislocation accumulation and dynamic recovery under the transmission from non-sheared to sheared precipitation when the strain rate is on the level of 3000/s∼5000/s. A modified Kocks-Mecking model was established to describe the mechanical property of AA 2B06. In addition, the high strain rate formability was evaluated by the new means which revealed the relationship between the impact energies, deep drawing height ratios and the deep drawing ratios by using the finite element modelling of the solid liquid coupling.