Pankaj Shrivastava, Velaphi Msomi, Sipokazi Mabuwa
This review presents a focused and critical evaluation of friction stir welding (FSW) for metal matrix composites (MMCs) as part of automotive structure, with comparative insights that are not typically brought together in the existing literature. In the current paper, the collective influences of reinforcement type, particle morphology, tool geometry, cooling strategy, and process parameters on the microstructural evolution in a strip-long direction in the context of particle redistribution, dynamic recrystallization, and intermetallic formation and defect suppression are systematically studied. A cross-comparison of the MMC systems used in automotive components is presented, focusing on the ability of FSW to achieve superior joint performance compared to fusion welding and identifying the conditions under which problems such as particle agglomeration, tunnel defects, and tool degradation still occur. The review combines findings from tensile, fatigue, hardness, and high-strain rate behavior to establish process-property-performance relationships that are relevant for crashworthy and lightweight vehicle applications. Recent developments in technology, such as advanced tool materials, hybrid improvement of FSW, active cooling, and real-time monitoring, are critically evaluated as they would subsequently affect weld integrity and scalability of production. Case Studies from Industrial Implementation Cases for the industrial implementation of FSW for MMCs assemblies for mass-manufactured automotive technology automotive platforms further illustrate the opportunities and the constraints in the adoption of FSW in the MMC assembly process. The review concludes with an identification of open issues, notably in nanocomposite welding, tool life, reinforcement-matrix interfacial control, and joining of dissimilar composite systems; and with targeted exercises for research to hasten integration of MMC-FSW in the manufacture of new automobiles.