Abstract
The friction stir welding (FSW) process is capable of joining all aluminium alloys, especially 2xxx and 7xxx aerospace alloys, with good joint properties. Successful weld quality was obtained for a dissimilar joint 2050-T3 Al–Cu–Li alloy/7449-TAF Al–Mg–Zn–Cu alloy at 20 mm thickness thanks to pulsation of the advancing speed. This FSW dissimilar joint was post-weld heat treated: 2050-T8/7449-T79. The joint ultimate tensile strength (UTS) was 336 MPa, similar to a 7449 bead on plate with the same thickness. Moreover, the fracture location takes place in the 7449 heat affected zone (HAZ), the weakest point indicated by the microhardness profile. The ‘pulsed’ process induces an improved stirring based on alternation of dark and light bands, whose chemical composition is close to 2050 and 7449 respectively.
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