Effect of CMT Welding Process Parameters on the Microstructural and Mechanical Properties of Dissimilar Aluminum Alloys of AA8011 and AA6061

The cold metal transfer welding process is a highly effective joining process of similar and dissimilar aluminum alloy plates due to its minimal spatter, stable arc, and low heat input. This work focuses on the joining of dissimilar alloys AA8011 and AA6061 with filler wire of ER4043 with different process parameters and investigates the correlation between the microstructure and mechanical properties of the weldments. Microstructural analysis revealed the presence of coarse grains along the partially melted zone (PMZ) boundaries and the equiaxed dendritic structures at the welded region. The equiaxed dendritic morphology in the weld fusion zone (WFZ) revealed enhancement of weld strength and hardness value, mainly due to effective dilution and the nonappearance of welding defects. This study highlights the complex interactions between microstructural features and mechanical performance in the weldments. The welded zone exhibited increased microhardness and tensile strength, resulting from the presence of delicate secondary phases in the weldments and a refined grain structure in the WFZ. X-ray diffraction confirmed the formation of critical intermetallic phases, including Al13Fe4, Mg2Si, and alpha-Al, distributed across the PMZ and welded region. The minimum ultimate tensile strength (UTS) of 79.84 MPa was perceived for sample-1, while the maximum UTS of 97.39 MPa was observed for sample-3. Overall, the study concludes that controlling the process parameters minimizes defects like phase imbalance and porosity while maintaining homogenous properties.