Investigation of the Synergistic Role of SiC Reinforcement and Heat Treatment in Friction Stir Welding Repair of Microcracks in Aluminum Alloy

Aluminum alloys are widely used in automotive, marine, and aerospace industries due to their excellent weldability and machinability but are prone to microcrack formation during service, leading to structural failure. This article proposes a novel friction stir welding repair strategy that incorporates SiC reinforcement combined with post‐weld solution heat treatment to enhance the repair performance of 6061‐T6 aluminum alloy. Unipolar and bipolar solution treatments are applied to 3‐mm‐thick plates. The addition of SiC not only promoted grain boundary strengthening but also significantly enhanced secondary phase strengthening. With 800 mesh SiC, the tensile strength increased to 292.1 MPa, 16.9% higher than the untreated sample. Heat treatment improved element distribution and further enhanced strengthening, with the bipolar solution‐treated sample achieving 339.2 MPa, a 35.09% increase. A 3D finite element model of the repaired joint is established to analyze stress distribution, revealing that SiC addition intensified local stress concentration. Therefore, the synergistic use of SiC reinforcement and heat treatment significantly improved the mechanical properties of repaired joints, providing an efficient strategy for the restoration of aluminum alloy components.