Detonator-assisted spot welding: A novel approach for joining dissimilar materials

In this study, a novel solid-state joining process, termed detonator-assisted spot welding, was developed and systematically investigated for the joining of similar and dissimilar metals. The process employs a detonator as a direct energy source, enabling a simplified welding configuration while generating high-velocity impact conditions capable of producing metallurgical bonding. The feasibility of the proposed technique was evaluated using JIS A1050/JIS A5052 and JIS A1050/SUS304 material combinations. Metallographic observations confirmed the formation of sound interfacial bonding, with interface morphology strongly influenced by the collision conditions. Vickers microhardness analysis revealed localized interfacial hardening associated with severe plastic deformation induced during impact. The tensile shear strength of the joints reached approximately 90–95% of the hardness-based reference strength, indicating effective bonding performance of the proposed process. High-speed imaging revealed dynamic flyer deformation behavior, including elliptical deformation and rapid acceleration during collision. A flyer velocity of approximately 945 m/s was obtained at a stand-off distance of 1.2 mm, which increased to a maximum at 4.2 mm, demonstrating the strong influence of stand-off distance on impact conditions and collision behavior. Furthermore, numerical simulations using smoothed particle hydrodynamics showed good agreement with experimental observations and provided insight into the transition in bonding mechanisms from plastic flow dominated bonding at the center to metal jet assisted bonding in the intermediate region. The results establish a correlation among process parameters, collision behavior, bonding mechanism, and mechanical performance. These findings demonstrate the potential of detonator-assisted spot welding as a compact high-rate solid-state joining technique for similar and dissimilar metals.