Fracture and Fatigue Mechanisms of Spot Friction Welds in Lap-Shear Specimens of Aluminum 6111-T4 Sheets

In this paper, fracture and fatigue mechanisms of spot friction welds in aluminum 6111-T4 lap-shear specimens are investigated based on experimental observations. Optical and scanning electron micrographs of these spot friction welds before and after failure under quasi-static and cyclic loading conditions are examined. The micrographs show the fracture and fatigue mechanisms of spot friction welds under quasi-static and cyclic loading conditions. The experimental observations indicate that the fracture mechanisms depend on the microstructure and geometry of welds under quasi-static loading conditions. Under cyclic loading conditions, the fatigue mechanisms depend not only on the microstructure and geometry of welds but also on the load amplitudes.