Defects and the properties of the dissimilar materials FSW joints of titanium alloy TC4 with aluminum alloy 6061

Titanium alloy TC4 and Aluminum alloy 6061 dissimilar material joints were made with friction stir welding method. The effects of welding parameters, including the stir pin position, the rotating rate and the travel speed of the tool, on the defects formation and the properties of the joints were investigated. The macrostructure of the joints and the fracture surfaces of the tensile test were observed with optical microscope and SEM. The reasons of the defects formation and the factors affecting the mechanical properties of the joints were discussed. When the welding parameters were appropriate, the joints fractured in the TMAZ and HAZ of the aluminum alloy and the strength of the joints could reach 68% of the aluminum base material strength.