Selection of FSW tool pin profile, shoulder diameter and material for joining AZ31B magnesium alloy – An experimental approach

In this investigation, an attempt was made to select proper tool pin profile, tool shoulder diameter and tool material to friction stir weld AZ31B magnesium alloy. Five tool pin profiles, five tool materials and three tool shoulder diameters were used to fabricate the joints. Tensile properties of the joints were evaluated and correlated with the weld zone microstructure and hardness. From this investigation, it is found that the joint fabricated using threaded pin profiled tool made of high carbon steel with 18 mm shoulder diameter produced mechanically sound and metallurgically defect free welds compared to their counterparts. The absence of defects in weld region, presence of very fine equiaxed grains in the weld region and higher hardness in the weld region are the main reasons for superior tensile properties of these joints.