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.