Tensile behaviour and microstructure evolution in friction stir welded 2195–2219 dissimilar aluminium alloy joints

2XXX series aluminium alloys are widely used in propellant tanks of space launch vehicles. In this work, friction stir welding (FSW) was performed to produce dissimilar joints between 2195 and 2219 alloys. The effect of temperature (ambient, 77K and 20K) on the tensile properties of 2195–2219 joints was investigated. Results showed that a decrease in temperature increased the tensile properties significantly without a reduction in ductility. Due to contribution from 2195 alloy, the properties of the dissimilar joint were marginally higher than the 2219 similar joint. The failure location in the thermo-mechanically affected zone (TMAZ) of the 2219 side was substantiated with the hardness survey across the weld. The effect of material position at advancing side (AS) and retreating side (RS) on tensile properties of dissimilar joints was investigated. Results depicted that regardless of the material position, the failure was consistently observed at TMAZ of 2219. However, placing 2219 at the AS showed better properties than at RS. This study brought out the tensile behaviour at cryogenic temperatures and suitable material position to achieve optimum strength, which are key inputs for designing launch vehicle structures.