High-quality friction pull plug welding of AA2219-T87 plate with a thickness of 18 mm: Experimental characterization on shaping, microstructure and mechanical properties

Abstract

In this study, the friction pull plug welding (FPPW) of a thick AA2219-T87 plate (nominal thickness = 18 mm) was conducted. The shaping, microstructure, and mechanical properties of the FPPW joint were characterized and discussed. The experimental results indicated that the defects accounted for the most influencing factor of the tensile properties of the FPPW joint. Further, the lack of bonding at the top and bottom of the joint was caused by insufficient dynamic recrystallization and the necking of the plug, respectively. Notably, the tensile tests revealed that kissing bonds were the main sources of the crack, which were significantly affected by dynamic recrystallization; they are readily formed at the top or bottom of FPPW joints. The detrimental phase, mainly the eutectics at the bonding interface, exerted less influence on the bonding strength. After adjusting the joint structure to achieve sufficient dynamic recrystallization at the top and preventing plug necking, high-quality FPPW joints were obtained; the average tensile strengths of their top, middle, and bottom layers were 323.4, 304.2, and 301.7 MPa, respectively, and their corresponding average elongations were 6.8%, 6.4%, and 5.5%, respectively.