The influence of convex shoulder on tribological and mechanical behavior of FSLW of aircraft assembly technology

Abstract

Regarding the challenges of welding for aluminum alloy, this research illustrates the influence of convex shoulder on mechanical and tribological behavior of friction stir lap welding of aircraft assembly technology. This research employs a spiral whirling needle convex shoulder, and the friction diffusion-welding test is carried out with 2024-T4 aluminum alloy sheets. Then the influence of the numbers of vortex-like needle convex shoulders on the cross-section morphology, material flow behavior, and mechanical properties are compared and analyzed. The experimental results show that there is no obvious bending phenomenon at the lapping interface under the action of a vortex-shaped stirring pin, and increasing the number of vortex-shaped structures is beneficial to increase the cross-sectional width of the nugget area. When the four vortex-shaped mixing needles are adopted, the effective lap width and fracture load of the lap joint with tensile fracture mode are greater than those with six vortex structures, respectively; the values are 11.74 mm and 17531.83 N.