Unveiling the Synergistic Effect of Tool Pin Profile on AA2219 Friction Stir Welds

The AA2219-T87 Al alloy was subjected to friction stir welding (FSW) using square, triangular, and conical tool pins. The investigation encompasses a comprehensive examination of material characterization in correlation to mechanical properties and corrosion behaviour. This study found that tool pin profile shape greatly affected weld joint structural and mechanical qualities. Distinct pin geometries create different plastic material flow patterns due to built-in heat and material transfer systems. The transmission electron microscopy (TEM) micrographs revealed striking differences in the precipitate characteristics. DSC (differential scanning calorimetry) traces the dissalution of precipitates over multiple weldments. The dynamic recovery in various weldments is demonstrated by the grain sizes and orientations disclosed by EBSD (electron back scattered diffraction) analysis. The PDP (potentio dynamic polarization) test found that welds created using a square tool pin design exhibited a relatively lower pit density. The square tool profile was found to produce enough heat to aid the flow of plastic material during friction stir welding, which led to this beneficial conclusion.