Experimental investigation of dilution, microstructure and fracture behavior in CMT-based WAAM of aluminum alloy

In this study, Al 5183 wire was deposited on AA6061-T6 substrate using a cold metal transfer (CMT) based wire arc additive manufacturing (WAAM) process. A Taguchi L9 orthogonal array was employed to optimize the welding current and travel speed of robotic welding torch for minimizing dilution while ensuring stable deposition. The novelty of this work lies in the use of a dissimilar material combination and the integration of dilution-oriented process parameter optimization with fractography-based porosity analysis, establishing a direct relationship between microstructure, defects and fracture behavior in WAAM-fabricated aluminum components. The zig-zag path deposition strategy was adopted for optimized condition. Material characterization and mechanical testing were also carried out for the WAAM-deposited sample under optimized parametric conditions. The field emission scanning electron microscopy with energy dispersive X-ray spectroscopy analysis was carried out for the tensile fracture surface. The fractography analysis revealed a ductile fracture characterized by dimples and microvoids. Pore morphology showed that most of the pores were within the 0–1 μm diameter range with circularity values between 0.5 and 0.7, indicating moderately rounded pore geometries. These findings provide practical guidance for process parameter selection to achieve controlled dilution and sound metallurgical bonding in dissimilar CMT-WAAM of aluminum alloys.