Unveiling heat-affected zone softening in dissimilar AZ31B and WE43 alloy welds

In this study, AZ31B-H24 and WE43-T5 Mg alloys were joined using friction stir welding. The effect of base material position, tool offset and rotational speed on the microstructure and mechanical properties was investigated. With AZ31B on the advancing side (AS), distinct layers of both materials were observed in the nugget zone (NZ), while material mixing in the NZ was better with WE43 on the AS. A maximum joint strength of 207 MPa (97% of AZ31B) was observed with AZ31B on the AS without tool offset and a tool rotation speed of 600 RPM. The failure location was at the thermo-mechanically affected zone/heat-affected zone of AZ31B side when AZ31B was on the AS, while joints with WE43 on the AS failed in the NZ.