Friction stir lap joining of 2198 aluminum-lithium alloy with weaving and pulsing variants

Lap joints of 2198-T8 Al-Li alloy in 0.063 in. sheet thickness were friction stir welded to investigate the combination of this material and assembly method for the manufacturing of aerospace structures. Along with conventional friction stir welding (FSW), weaved FSW and pulsed FSW (PFSW) were evaluated to determine the potential impact of these variant technologies on weld strength. Additionally, a more traditional flat shoulder tool geometry operated with a tilt angle was compared to a tapered shoulder tool geometry operated at a 0° tilt angle, which offers the possibility of simplifying robotic welding operations. Faying surface sealant, the use of which is critical in aerospace applications, was investigated as well, to determine its impact on weld strength and to characterize its interactions with welding parameters and process variants.