Shipboard wire arc additive manufacturing under oscillatory conditions: Process analysis and forming characteristics

The shipboard Wire Arc Additive Manufacturing (WAAM) provides the potential for the production and repair of critical components during offshore operations, enabling rapid, on-demand fabrication in ocean environments. However, research on the WAAM process for maritime environments is still in the exploratory stage. Therefore, to investigate the formability of WAAM under oscillatory conditions typical of shipboard environments, this study simulates three sea state conditions: low, moderate, and high. Thin-walled components are printed using low-carbon steel ER50-6 under simulated ship oscillation. The morphology and surface quality of the printed components are characterized, and real-time current, voltage, and image signals are collected. Process monitoring and feature extraction are employed to analyze arc behavior, droplet transfer, and melt pool morphology, allowing for an evaluation of the forming characteristics under oscillation. Results indicate that oscillatory conditions impair the continuity of spectral peaks in current and voltage signals, with the coefficient of variation rising by over 30%. As oscillation intensity increases, the droplet transfer mode shifts from stable spray transfer to large droplet transfer, accompanied by arc instability and transient short circuits. At higher oscillation levels, the surface quality of thin-walled components declines markedly, with metal flow marks visible on the sides. In simulated shipboard conditions, droplet deflection and arc deviation increase, leading to larger droplet sizes and prolonged transfer times. Based on the findings, this study proposes that maintaining shorter droplet transfer cycles and smaller droplet sizes is crucial for ensuring process stability in shipboard WAAM applications.