Characterization of superplastic response in Al-Mg alloys

The ability to achieve large strains to failure coupled with extremely low flow stresses makes superplastic forming an attractive option in the automotive industry for the manufacture of complex parts from aluminum sheet. However, a barrier to increased usage is the cost penalty associated with alloys that are specially processed to have a small and stable grain size which makes them suitable for superplastic forming. In this paper, a series of elevated-temperature tensile tests are used to characterize the superplastic response of Al-Mg alloys that were specially processed for superplastic forming as well as an alloy which was conventionally processed. Results from these tensile tests coupled with optical microscopy are used to both establish the superplastic forming potential of these alloys as well as to highlight the different mechanisms that control deformation and cavitation in the two types of materials.