Effect of anisotropy on fatigue properties of 2198 Al–Li plates joined by friction stir welding

Al–Li alloys are characterized by a strong anisotropy in mechanical and microstructural properties with respect to the rolling direction. In the present paper, 4 mm sheets of 2198 Al–Li alloy were joined via friction stir welding (FSW) by employing a rotating speed of 1000 mm/min and a welding speed of 80 mm/min in parallel and orthogonal direction with respect to the rolling one. The joints mechanical properties were evaluated by means of tensile tests at room temperature. In addition, fatigue tests were performed by using a resonant electro-mechanical testing machine under constant amplitude control up to 250 Hz sinusoidal loading. The fatigue tests were conducted in axial control mode with R = σmin/σmax = 0.33, for all the welding and rotating speeds used in the present study.