Effect of process parameters on third generation of friction stir welded Al-Li alloy plates

In the present investigation, low density and high strength aluminum-lithium alloy was joined by friction stir welding (FSW) with a taper threaded tool at different process parameters. The experimental joint was carried out at different fundamental process parameters like tool traverse speed (TTS; 6, 8, and 10 mm/s) at a constant tool rotating speed (TRS;1000 rpm), and different TRS (1900, 2200, and 2500 rpm) with constant TTS (10 mm/s), and tool tilt angle (TTA) of 2 degrees. The effects of changing TRS and TTS on force and torque, ripple distance, surface roughness, microstructure, and tensile properties of welded samples were investigated. The results show that the force and torque decrease with increased rotational speed and the reverse trend follows with increasing TTS. It may be due to the generation of frictional heat during FSW. The surface roughness values of FSW samples in the nugget zone and advancing side to retreating side increased as rotational speed increased. The surface roughness values of welded samples were reduced as traverse speed was raised with a constant rotational speed of 1000 rpm. Higher tensile strength (343.59 MPa) is attained at 1900 rpm (TRS) and 10 mm/s (TTS) due to the fine equiaxed grain size in the nugget zone (11.57 mu m) and observed ductile mode of failure.(c) 2022 CIRP.