Analysis of Hybrid Pin Profiles and Traverse Speed Effects on Weld Geometry, Grain Structure, and Strength in FSW of 2050-T84 Al-Li Alloy

The aerospace alloy 2050-T84, with its high strength, low density, reduced fatigue crack growth resistance, and corrosion resistance, is a widespread alternative for automotive parts, marine, and aviation construction. A hybrid tool pin (HTP) profile was applied in Friction Stir Welding (FSW) to join the 2050-T84 alloy, at different higher traverse speeds (TS) (of 4, 6, 8, and 10 mm/s) and a constant tool rotation speed (RS) of 1400 rpm for speeding up production. The consequences of HTP and higher TS on the microstructure, joint strength, weld bead structure, and tensile strength of FSWed alloy plates are investigated in the present study. The consequences showed that torque and force increased with TS, reaching their maximum values at 8 mm/s, and then decreased. At a TS of 8 mm/s, the microstructural analysis showed enhanced strength, joint quality, and grain refinement. However, a void defect was observed at 10 mm/s, indicating inadequate heat input. The outcomes demonstrate that the performance of FSW joints in aerospace-grade Al-Li alloys is enhanced by a hybrid tool design in combination with an improved traverse speed of 8 mm/s.