An Experimental Approach to Study the Effect of Welding Parameters on Similar Friction Stir Welded Joints of AZ31B-O Mg Alloy

In this investigation an attempt has been made to study the effect of friction stir welding parameters on mechanical and metallurgical properties of AZ31B-O Mg alloy joints. The selected material was welded using combination of different parameters i.e. tool rotational speed, welding speed and tool shoulder diameter. The effect of weld pitch i.e. ratio of welding speed to tool rotational speed (0.0020 mm/rev to 0.05 mm/rev) was examined on the mechanical and micro structural properties of friction stir welded joints of AZ31B-O Mg alloy. The linear relationship between tensile strength and weld pitch was observed. The maximum value of tensile strength i.e. 187.8 N/mm2 was obtained at weld pitch of 0.05 mm/rev using 20 mm tool shoulder diameter. Most of the tensile test specimens fractured in the area between Stir Zone (SZ) and Thermo Mechanical Affected Zone (TMAZ) towards the advancing side. The fine and equiaxed grains were observed due to dynamic recrystallization at higher value of weld pitch.