Enhancing surface properties and microstructure through influence of tool pin profiles on friction stir welded Al-Mg alloy

This investigation is effort to enhance the mechanical properties on friction stir welded Al-Mg alloy with different processing levels like tool pin profiles, tool rotational speed and welding speed and the other parameters like tool tilt angle and tool axial load is kept constant for all the runs. The tool pin profiles (straight pentagonal cylinder (SPC), straight cylinder (SC) and straight fluted cylinder (SFC)), tool rotational speed (1000, 1300 and 1600 rpm) and tool traverse speed (30, 40 and 50 mm/min) is processing input factors. Those FSWed samples are considered to conduct the mechanical properties like tensile strength and microhardness is investigated. The optical microscope investigations are utilized to identify the finer grain structure on welded Al-Mg alloy. The ultimate tensile strength is attained at the processing levels (1000 and 1600 rpm, 30 and 50 mm/min and SPC and SC). The maximum hardness was attained on the stirred zones of FSWed Al-Mg alloy for the process parameters (1300 rpm, 30 and 40 mm, SFC and SC), respectively. The poorer grain structure was attained on the stirred regions of Al-Mg alloy due to mechanical mixing is not properly maintained by the selected processing parameters. The microstructure of friction stir welded Al-Mg alloy shows the better fine refinement due to enhancing stirring action by the optimal process parameters.