Study of technology and structure property on friction plug welding of dissimilar aluminum alloy

Based on the friction push plug welding method, the investigations of friction plug welding experiments for AA2024-T3 and 7075-T6 friction stir welds with 8 mm thickness by using the AA2219-T6 plugs were performed, the varying features of microstructures, micro-hardness profiles, mechanical properties and fracture modes of various welding pressure have been analyzed in detail. The results showed that tight joints were obtained between plug and base metal or FSW welds. The transition zone from plug to base metal or FSW welds consisted of equiaxed grains. Grain growth occurred in the thermo-mechanically affected zone and heat affected zone. Micro-hardness of plug zone was 85~95 HV, which is the weakest areas of whole FPW joints. The tensile strength and elongation of AA2024 FPW joints can reach above 70% and 65% of the base metal respectively. The tensile strength and elongation of AA7075 FPW joints can reach above 62% and 48% of the base metal respectively. The fracture modes of FPW joints were ductile.