Joining of AZ91 Mg alloy and Al6063 alloy sheets by friction stir welding

Abstract

In the present work, the effect of process parameters on joining of AZ91 Mg alloy and Al6063 aluminum alloy sheets during friction stir welding (FSP) was studied. A successful joint was achieved at 1100 r.p.m. tool rotational speed and 25 mm/min tool travel speed. Combination of tool rotational speed and tool travel speed has observed a profound effect on the material flow mechanisms at the nugget zone. From the microstructural studies, the joint formation was observed as mainly due to mechanical mixing of the materials. The level of metallurgical continuity at the nugget zone was observed as poor and a sharp interface at the joint was noticed. The microhardness measurements across the weld joint also revealed the lack of establishment of a perfect metallurgical bonding. X-ray diffraction analysis of weld zone showed presence of both magnesium and aluminum. Hence from the preliminary observations, it can be understood that the joining of AZ91 Mg alloy and Al6063 alloy can be achieved by FSP; however, complex issues in material mixing still need further investigations. Keywords: Friction stir welding, Dissimilar joints, Magnesium, Aluminum, Nugget zone