Hybrid Weld-Bonded Joints: A Critical Comparative Review of Welding Processes, Adhesive Interaction and Joint Performance

Weld-bonded joints combine localized metallic welding with structural adhesives and are increasingly used in lightweight multi-material structures. Although numerous studies have examined individual weld-bonding processes, the available literature remains fragmented with respect to process classification, adhesive-weld interaction and mechanical performance. This paper presents a critical review of hybrid weld-bonded joints published between 2000 and 2026, with emphasis on welding-based joining processes and their influence on joint behavior. The main weld-bonding techniques, including resistance spot weld-bonding (RSWB), friction stir weld-bonding (FSWB), friction stir spot weld-bonding (FSSWB) and laser weld-bonding (LWB), are systematically compared in terms of heat input, adhesive stability, load transfer mechanisms and mechanical performance. The analysis indicates that processes with lower heat input, such as FSWB and FSSWB, provide improved adhesive preservation and fatigue performance, whereas RSWB remains the most industrially established solution. The influence of different adhesive families (epoxy, polyurethane, acrylic and thermoplastic) is evaluated with respect to thermal resistance, rheological behavior during welding and long-term durability. Mechanical performance under static, fatigue and impact loading is critically assessed, highlighting typical strength improvements compared with purely welded joints and identifying dominant failure modes. In addition, numerical modeling approaches, including finite element and cohesive zone methods, are reviewed in terms of their ability to capture coupled thermomechanical and damage phenomena. The review further outlines key industrial applications, current technological limitations and future research directions, including advanced adhesive systems, low-heat-input processes, non-destructive testing and digital-twin-based optimization.