Complex-geometry metal parts in arc-directed energy deposition: Fabrication methods, defect formation mechanisms, quality improvement strategies

Arc-directed energy deposition (arc-DED) is a promising technology for fabricating medium to large-scale metal components due to its high deposition rates and significant cost-effectiveness. However, the widespread industrial application of arc-DED is hindered by various defects that frequently occur during the fabrication of intricate geometries. Therefore, advanced fabrication methods and robust quality improvement strategies are essential for achieving high-precision and reliable production of complex-geometry components. This paper provides a comprehensive review of recent developments in fabrication methods for complex geometries (i.e., overhangs, corners, crossings, and lattices). The relationship between defect formation mechanisms and specific geometric features is systematically analyzed, and quality improvement strategies aimed at eliminating these defects are discussed. The slicing and path planning strategies for complex structural models are introduced. Various methods for parameter optimization and closed-loop control are summarized. The paper concludes by presenting future outlooks for developing intelligent and adaptive strategies for the fabrication of metal parts with complex geometries. This review provides a foundational reference for realizing defect-free and high-efficiency fabrication in arc-DED industrial applications.