Investigation on mechanical properties of friction plug welded joints for 2219 friction stir welds

Based on the friction push plug welding method, the investigations of friction plug welding experiments for 2219-T87 friction stir welds with 8 mm thickness by using the 2219-T6 plugs have been performed. The varying features of microstructures, mechanical properties at room, low temperature conditions, micro-hardness profiles and fracture modes have been analyzed in details. The results show that the microstructures of FPW joints was obviously inhomogeneous. The joints are mainly composed of plug zone, plug thermo-mechanical affected zone, recrystallization zone, base metal thermo-mechanical affected zone, heat affected zone and base material. The grains in the thermo-mechanically affected zone of base metal is the weakest areas of whole FPW joints at which the grains have the obviously deformed features and the lowest micro-hardness of 85 HV, which are the tensile strength of FPW joints at room and low temperatures can reach above 80% of FSW joint, the elongation can reach above 70%, and the fracture modes of FPW joints are possessed of ductile features.