The development of a high strain rate superplastic Al-Mg-Zr alloy

In order for superplastic forming of aluminium to break out of the niche market low cost alloys are required that exhibit higher strain rate capability that are capable of volume production. This paper describes an investigation into the feasibility of producing such an alloy. A series of Al-4Mg alloys with 0, 0.25, 0.5, 0.75 & 1% Zr additions was prepared using a cheap particulate casting route, in an attempt to achieve higher levels of Zr supersaturation than are possible with conventional casting. The particulate was processed into a sheet product via hot extrusion followed by cold rolling and the effect of a number of process variables on the SPF performance of the sheet was investigated. It was found that increasing the Zr content, and manipulation of the thermomechanical processing conditions improved the SPF performance. Ductilities in excess of 600% have been achieved at a strain rate of 0.01 s-1, together with flow stresses less than 15MPa.