Abstract

Wire Arc Additive Manufacturing (WAAM) has emerged as a promising metal additive manufacturing technology due to its high deposition rates, cost-effectiveness, and suitability for large-scale structural components. This review discusses the main research trends, process parameters, microstructural evolution, defect formation mechanisms, and mechanical performance associated with WAAM-fabricated components. Particular emphasis is placed on the influence of key processing parameters-current, voltage, travel speed, and wire feed rate-on heat input, bead geometry, melt pool stability, and resulting microstructure. The mechanics of bead formation and deposition geometry are analyzed in terms of thermal-fluid interactions and mass conservation principles, highlighting their impact on layer uniformity and structural integrity. Persistent technical challenges are examined, including porosity, lack of fusion, residual stresses, geometric distortion, and anisotropy in mechanical properties resulting from the layer-by-layer thermal cycling. The review further addresses the complexity of multi-material deposition, where thermal mismatch and intermetallic phase formation represent significant barriers to reliable structural integration. Emerging research directions are discussed, including advanced wire development, functionally graded materials, real-time process monitoring, predictive thermo-metallurgical modeling, robotic motion optimization, and process standardization. The need for harmonized qualification protocols and robust databases is emphasized as a critical step toward large-scale industrial adoption, particularly in aerospace, naval, energy, and advanced manufacturing sectors (Figure 1).

Keywords:Wire arc; Material deposition; Fabrication; Superalloys; Stainless steels; Electrode; Geometry; Metallurgical simulation