Friction Stir Processing of Heat Treated A380 Al Alloy to Enhance Surface Characteristics

Friction stir processing (FSP) has been increasingly used to improve the surface characteristics of Al alloys. Investigation on FSP of heat-treated A380 Al alloy was performed to examine the impact of tool rotation speed on the surface characteristics. Heat treatment was accomplished using solution heat treatment followed by age hardening. The microstructure of the unprocessed and processed regions was characterized by utilizing an optical microscope, XRD, SEM and EDS. Surface properties were determined using hardness and pin-on-disk wear tests. The results showed that the heat treatment transformed the morphology of the silicon in the alloy matrix from fibrous to globular. FSP refined the microstructure in the stir zone due to the stirring effect. Hardness increased with an increment in the tool rotation speed due to increased densification of the stirring area. The wear test displayed the significant impact of the tool rotation speed on the wear rate as the wear rate decreased when the tool rotation speed tended to the highest value. The results also displayed that abrasive and delamination are the main mechanisms of surface deterioration.