Enhancing additive manufacturing quality of Inconel 718 through interpass temperature control in robotic CMT-WAAM

Wire Arc Additive Manufacturing (WAAM) has emerged as a viable solution for the fabrication of high-value, large-scale metallic components, particularly utilizing nickel-based superalloys such as Inconel 718. Despite the promise of reduced lead times and material waste, challenges such as porosity, micro-segregation, and thermal-induced defects persist. This study investigates the influence of interpass temperature on porosity evolution, microstructural characteristics, and mechanical performance of Inconel 718 components manufactured via a robotic Cold Metal Transfer (CMT) Gas Metal Arc Welding WAAM process. Controlled interpass temperatures of 100 °C and 200 °C were employed to deposit wall structures layer-by-layer. Non-destructive computed tomography (CT) was utilized for pore quantification, while tensile testing and metallographic analysis were conducted to evaluate structural integrity. Results revealed that a higher interpass temperature of 200 °C led to a 13.3% reduction in overall porosity and a significant decrease in maximum pore volume, although it resulted in coarser dendritic structures (≈22 µm) compared to the 100 °C condition (≈15 µm). The study key findings suggest that while higher interpass temperatures facilitate gas escape and reduce detrimental pores, they induce strength-ductility trade-off through microstructural coarsening. This research provides a quantitative framework for optimizing thermal strategies in high-performance aerospace and industrial applications.