Strategies for Controlling Metallurgical Transformations and Mechanical Properties in Al/Steel Friction Welding: A Review

Abstract

Abstract. With the growing demand for lightweight and high-strength structures in fields such as aerospace and automotive engineering, aluminum alloy/steel (Al/steel) hybrid structures, combining the low density of Al with the high strength of steel, have gained widespread applications. Focusing on Al–steel friction welding, this review explores metallurgical evolution and control methods in this solid-state joining process characterized by low heat input and high joint strength. However, significant differences in physical and metallurgical properties often lead to interfacial challenges, including the formation of brittle intermetallic compounds, residual stresses, and structural inhomogeneities. This review highlights research advances made over the past decade in thermomechanical regulation, interfacial metallurgical optimization, and novel assisted welding techniques. Furthermore, strategies such as geometric interface design, interlayer insertion, and the development of novel three-body friction welding configurations are discussed as effective methods to improve joint quality and reliability. It also identifies the key challenges in quality control for welding large-scale components and in evaluating the service performance of dissimilar joints. Overall, this review provides valuable control strategies and outlines future research directions for achieving high-reliability Al/steel friction welds.