Fatigue Performance and 3D Residual Stress Map of Refill Friction Stir Spot Welded 2219 Aluminum Joints

For many years, the aviation industry has been closely monitoring friction-based welding due to its ability to reduce weight, circumventing the challenges associated with fusion-based welding. This technology also enables the joining of materials that are traditionally deemed challenging to weld using conventional methods. Refill Friction Stir Spot Welding (refill FSSW) emerges as a solid-state joining process with substantial potential to replace single-point joining techniques like riveting.
This research centers on applying Refill Friction Stir Spot Welding (Refill FSSW) to the high-strength aluminum alloy, AA 2219. It aims to explore various aspects of the welding process, including the fatigue behavior of the joint, the mechanisms of crack nucleation and propagation, with a particular emphasis on analyzing the residual stress within the weld.
Analogous to friction stir welding (FSW), the intricate interplay of nonuniform plastic deformation, thermal gradients, heterogeneous material flow, and rapid microstructural changes during refill FSSW invariably induces internal residual stresses.
Understanding the 3D residual stress field introduced by refill FSSW is essential for developing crack propagation models, a critical step for the industrial application of this technology.