Synergistic regulation of alternating magnetic field and torch tilt angle for high-precision fabrication of self-supporting inclined aluminium alloy components via CMT-WAAM

Wire arc additive manufacturing (WAAM) of inclined wall structures faces critical challenges, including significant deviations between actual and theoretical inclination angles, pronounced macro-morphology discrepancies between the upper and lower parts of components, heterogeneous and unevenly distributed microstructures across deposited and internal layers, and anisotropic mechanical properties. These issues severely hinder the application of inclined wall components. To address these problems, this study proposes a quantitative control strategy that applies a millitesla-level alternating electromagnetic field to the tip of a tilted welding torch. Systematic experiments encompassing additive manufacturing, microstructure characterization, and mechanical property testing were conducted. A simplified analytical model of the molten pool was established to investigate its flow behavior and predict the welding torch inclination angle under single-pass and multi-layer deposition conditions. The experimental results demonstrate that the synergistic regulation of a 4 mT alternating magnetic field (AMF) and a 20° torch tilt angle significantly enhances the forming accuracy and quality of CMT-WAAM aluminum-based inclined walls. The alternating Lorentz force generated by the AMF stirs the molten metal, facilitating bubble escape and increasing nucleation sites, while also suppressing columnar grain growth and Al-Si eutectic segregation. Combined with the optimized arc pressure distribution induced by the torch tilt angle, the high-inclination aluminum alloy components achieve excellent mechanical properties. This study further elucidates the mechanism underlying the collaborative regulation of component formation and performance by the alternating electromagnetic field and torch tilt angle, laying a solid experimental and theoretical foundation for the in-situ fabrication of high-inclination components.