Effect of Single Pass and Double Pass on Friction Stir Welded Aluminium Alloy 6063 using Square Tool Pin Profile

Solid state joining process named Friction Stir Welding was developed in 1991 which has attracted considerable interest from the aerospace and automotive industries, since it is able to produce defect free joints particularly for light metals i.e. magnesium and aluminium. Aluminium alloy AL 6063 is medium strength architectural alloy, normally used in intricate extrusions. Due to difficulties in welding Aluminium using conventional welding processes, Friction Stir Welding has been used to weld aluminium alloy AL 6063. The effect of single pass and double pass was studied using combination of different parameters i.e. Square tool pin profile, tool rotational speed (1400 rpm), welding speed (35mm/min) and tool shoulder diameter 21 mm. The square pin (7×7 mm) profile was used to make a butt weld joint by using single pass, double pass (same side) and double pass (reversed side).Results was compared by studying the effect of number of passes on the tensile strength and micro hardness Test. After testing, the effect of single pass and double pass on friction stir welded aluminium alloy 6063 using square tool pin profile are concluded, it was observed that the maximum value of UTS i.e. 168.5 N/mm² was obtained at 1400 rpm tool rotational speed, 35 mm/min welding speed with square tool pin profile with double pass (same side) friction stir welding. The Vickers hardness value was maximum at stir zone i.e. 87 Hv with 1400 rpm tool rotational speed, 35 mm/min welding speed with square pin profile with double pass (same side)and(reversed side) as compared with the heat affected zone (HAZ) and thermo mechanically affected zone (TMAZ).