Influence of axial force parameters to the quality of friction pull plug welding for 2219-T87 aluminium alloy sheets

In this study, we performed a friction pull plug welding process successfully on 8-mm-thick 2219-T87 plates. The influence of the welding process on the weld formation and defects are investigated. The defect characters, grain structures, precipitate evolutions and tensile properties of the weld are examined. It was found that the axial force plays a crucial role in influencing the weld formation and defect characters. In thermal mechanically affect zone nearby the bonding interface, the grains might be highly deformed and recrystallised owing to the severe plastic deformation. Besides, the strengthening precipitates might be dissolved during welding. Near the bonding interface, as the hardening effects from cold work and precipitation have been weakened, the hardness in this region was reduced obviously. The ultimate tensile strength and elongation of defect free welds may reach 310 MPa and 6.5% respectively. This reveals that FPPW technology has the potential for the application in aerospace industrial field.