Friction stir welding parameters and their influence on mechanical properties of welded AA6061 and AA5052 aluminium plates

Friction stir welding (FSW) process is the preferred technique for joining of dissimilar metals. This paper intends to provide comprehensive study on the mechanical and metallurgical properties of dissimilar friction stir welded aluminium alloys, AA6061 and AA5052. The objective of the study is to find the optimum welding parameters at which the maximum weld joint strength can be achieved and to identify the influence of those parameters on the weld strength and microstructure of the AA6061 with AA5052 welded joints. The FSW process parameters such as traverse speed, tool rotational speed, axial force and tilt angle were considered. The mechanical properties measured are yield strength, tensile strength and percentage of elongation. Scanning Electron Microscopy (SEM) and optical microscope were used to observe the microstructure of weld zone (WZ) and heat affected zone (HAZ) of welded samples. Energy Dispersive x-ray Analysis (EDS) was used to obtain the elemental composition at the weld zone. Visual inspection reveals that there is no existence of weld defects like voids and porosity developed on the surface of the joints. The welds produced by the dissimilar aluminium alloys exposed an equiaxed and fine-grained structure in the weld zone. Analysis of variance (ANOVA) Technique is used to check the adequacy of the developed mathematical model. The difference between calculated and adjusted R-2 is 0.2 which indicates that the model is adequate. The percentage error is also less for the estimated and predicted values of the properties of welded joints.