Effect of Friction Stir Processing Parameters on Microstructure and Mechanical Properties of AL 5059

Wrought aluminum alloy 5059 was friction stir processed with 3 different tool pin geometries, and varying rotation speeds. After friction stir processing microstructural characterization was carried out by optical microscopy, SEM and TEM. Grain size measurement was performed on the samples to investigate the effect of process parameters on recrystallization and grain growth in the stir zone. Mechanical properties were also obtained by microhardness and tensile tests.  Preliminary results indicate that a fine grained structure is achieved with improved mechanical properties. A tool with 3 flats in combination with a rotation speed of 580 rpm provides the best grain refinement and subsequent mechanical properties.