不等厚2219铝合金板回填式搅拌摩擦点焊接头组织及性能研究

According to the requirements of aerospace technology, refill friction stir spot welding technology was used to weld 2219 aluminum alloy plates with different thickness (2 mm+8 mm). By changing welding process parameters (rotation speed, welding time and plunge depth), the influences of welding parameters on the microstructure and mechanical properties of welded joints were analyzed. The results show that with the increase of rotation speed, the tensile-shear strength of the joints increases first, and then decreases. The extension of welding time can increase the tensile-shear force of the joint, but too long time will lead to the reduction. The selection of plunge depth should not only ensure the combination of upper and lower plates, but also not lead to excessive softening of lower plates. What's more, when the rotation speed is 1 800 r/min, the welding time is 6 s, and the plunge depth is 2.6 mm, the optimal tensile-shear force of the joint is 7 924 N. There are three fracture modes of refill friction stir spot welded joints: plug fracture, shear fracture and plug-shear fracture. Among them, the tensile-shear force of the spot welded joint is larger when the type of plug-shear fracture occurs.