Superplastic Behavior of Overaged 2024 Aluminum Alloy after Friction Stir Processing

A commercial 2024 aluminum alloy was heat treated at 280 °C for 48 h and then slow cooled in a furnace to obtain minimum hardness. This material friction stir processed (FSP) using three sets of processing conditions. To study the effect on microstructure high temperature mechanical properties, materials were tested tension an initial strain rate 10−2 s−1 range 200 450 °C. Processing severity selected as main factor obtaining fine grain sizes right after FSP. The size enormously reduced from about 50 µm 1 µm. reduction gave rise very elongations failure 400%. Strain–rate-change tests showed stress exponent close 2 intermediate rates, which related boundary sliding controlling deformation mechanism superplasticity, is strongly grain-size dependent. possible by solute-drag creep, proposed other authors, disregarded since conducted °C, where FSP coarsens rapidly, low elongation resistance, importance dependence operative 250–400 only compatible with sliding.