Hybrid Additive Manufacturing via Wire Arc Metal Deposition and Deformation for Microstructure Refinement and Performance Enhancement

Wire Arc Additive Manufacturing (WAAM) is a cost-effective and scalable technique for producing large metallic components; however, coarse columnar microstructures, strong crystallographic texture, and significant residual stresses limit its widespread adoption. In recent years, hybrid WAAM processes integrating deformation-based techniques have been developed to address these limitations. This review provides a comprehensive analysis of deformation-assisted WAAM, encompassing interlayer rolling, friction stir processing (FSP), hammer peening, laser shock peening, and ultrasonic vibration-assisted approaches. These hybrid techniques introduce additional thermomechanical parameters—strain, strain rate, and applied stress—that significantly influence microstructure evolution. The governing physical metallurgy mechanisms are discussed in detail, including dislocation accumulation, recovery, static and dynamic recrystallization, and severe plastic deformation. Studies from 2022 to 2025 are critically reviewed, highlighting the effectiveness of hybrid WAAM in promoting columnar-to-equiaxed grain transformation, reducing anisotropy, mitigating defects, and improving mechanical properties across aluminum, titanium, steels, and nickel-based alloys. The integration of auxiliary processes such as in-situ machining and heat treatment is also discussed. This review establishes a process-structure-property framework for hybrid WAAM and provides guidance for the development of advanced additive manufacturing systems capable of delivering near-net-shape components with microstructures and properties approaching those of wrought or forged counterparts.