Superplasticity of the rolled and friction stir processed Al–4.5 Mg–0.35Sc–0.15Zr alloy

The article describes the effect of friction stir processing (FSP) on the superplastic behaviour of the Al–4.5 Mg alloy containing Sc and Zr. The results yielded by the FSPed sheet were compared with the superplastic behaviour of the same alloy produced conventionally by cold rolling. The measurements of the superplasticty included the flow stresses and the maximum elongations of the alloy at initial strain rates ranging from 1×10−3 s−1 to 1 s−1, and at testing temperatures from 350 °C to 500 °C. The inclusion of the FSP step considerably enhanced the superplastic behaviour of the alloy in comparison with its rolled counterparts, which was reflected in higher elongations at higher strain rates and lower forming temperatures.