Abstract
Commercial 5083 Al rolled plates were subjected to friction stir processing (FSP) with two different processing parameters, having 430 and 850 rpm tool rotational speed with a single traverse feed rate of 90 mm/min. These FSP conditions resulted in two fine grained microstructures of 0-95 mu m (430 rpm) and 2.6 mu m (850 rpm). Tensile elongations were measured at a relatively low temperature of 250 degrees C at three strain rates, and demonstrated that a decrease in grain size resulted in significantly enhanced ductility and lower forming loads. The occurrence of a relatively high value of strain rate sensitivity, m of 0.45 for a grain size of 0.95 mu m, suggests the operation of superplastic deformation under these present experimental conditions.