An experimental investigation of fatigue behavior and deformation of double spot friction welded joints

•A new style of SFW joints has been introduced as double welded joints configuration.•The strength of fabricated joints under tensile and fatigue tests have been determined.•The capability of SFW technique in joining more than two sheets has been demonstrated.

Fatigue behavior of double spot friction welded joints in aluminum alloy 7075-T6 plates is investigated by conducting monotonic tensile and fatigue tests. The spot friction welding procedures are carried out by a milling machine with a designed fixture at the best preliminary welding parameter set. The fatigue tests are performed in a constant amplitude load control servo-hydraulic fatigue testing machine with a load ratio of (R = Pmin/Pmax) 0.1 at room temperature. It is observed that the failure mode in cyclic loading (low-cycle and high-cycle) resembles that of the quasi-static loading conditions i.e. pure shearing. Primary fatigue crack is initiated in the vicinity of the original notch tip and then propagated along the circumference of the weld’s nugget.