Cryogenic properties of Al–Mg–Sc–Zr friction-stir welds

In this work, the effect of friction-stir welding (FSW) on the microstructure and cryogenic properties of an Al–Mg–Sc–Zr alloy was studied. The produced friction-stir joints demonstrated both excellent static and dynamic mechanical properties at cryogenic temperatures. The joint efficiency for the yield strength during transverse tensile tests was in the range of 95–100%, whereas the impacts fracture toughness in the stir zone was found to be superior compared with that in the base material. The high level of the mechanical properties was attributed to the preservation of Al3(Sc,Zr) dispersoids, extensive grain refinement and the breaking of the continuous grain boundary network of the coarse Al6Mn particles during FSW.