Effect of Friction Stir Processing on the Microstructure and Mechanical Properties of A384 Aluminum Alloy

Friction stir processing (FSP) is a solid-state technique for microstructural modification. The aim of this work is to evaluate the effect of input process parameters of friction stir processing (tool rotational speed rpm, travel speed mm/min) on microstructure and mechanical properties of A384 aluminum alloy. A384 aluminum alloy was cast using conventional stir casting process. The obtained alloy was subjected to friction stir process using different input parameters (rpm, mm/min) with double pass. Water was used as cooling medium during process. The microstructures of investigated alloys were characterized by optical, SEM microscopes, EDS and Map analyzer, while mechanical properties were evaluated by using tensile test. The results indicate that; after friction stir processing, the microstructure of as-cast alloy was greatly improved. Needle-like eutectic Si and Chinese Script a-Fe were modified to fine precipitates. Meanwhile, coarse primary Si and large plate b-Fe phase were dissolved. On the other hand, mapping analysis shows homogenous distribution of different alloying elements through the matrix. The higher values of tensile properties were obtained at 1200 rpm and 80 mm/min. UTS and YS were increased by 98% and50%, respectively. Meanwhile, ductility was approximately three times higher than that of cast alloy.