摘要
Double-side probeless friction stir spot welding (DP-FSSW) of AA2198 alloy was conducted to investigate the microstructure and mechanical properties. Compared with common single-side probeless friction stir spot welding (P-FSSW), the plastic strain during DP-FSSW is nearly symmetrical with respect to the bondline to suppress the extension of hook defect, which is detrimental to the joint mechanical strength. With DP-FSSW, a fully metallurgically bonded region has formed due to severe plastic deformation at high temperatures. Tensile/shear tests show that the joint strength could exceed 8 kN, which is comparable to P-FSSW and refill FSSW, and all fractures happen in a shear failure mode as cracks extend along the in terface of two sheets. The microhard ness profile exhibits a uniform distribution along the thick ness direction, in which the hook defect shows the lowest value.
Double-side probeless friction stir spot welding(DP-FSSW) of AA2198 alloy was conducted to investigate the microstructure and mechanical properties. Compared with common single-side probeless friction stir spot welding(P-FSSW), the plastic strain during DP-FSSW is nearly symmetrical with respect to the bondline to suppress the extension of hook defect, which is detrimental to the joint mechanical strength.With DP-FSSW, a fully metallurgically bonded region has formed due to severe plastic deformation at high temperatures. Tensile/shear tests show that the joint strength could exceed 8 kN, which is comparable to P-FSSW and refill FSSW, and all fractures happen in a shear failure mode as cracks extend along the interface of two sheets. The microhardness profile exhibits a uniform distribution along the thickness direction, in which the hook defect shows the lowest value.
基金
financially supported by the National Natural Science Foundation of China (No. 51574196)
the Aeronautical Science Foundation of China (No. 20161125002)
the “111 Project” (No. B08040)
