Fine equiaxed zone induced softening and failure behavior of 7050 aluminum alloy hybrid laser welds

A fine (~3–10 μm) equiaxed zone (FQZ) between the heat affected zone and the weld metal is a unique microstructural feature associated with fusion welded Zr-containing aluminum alloys, posing a significant threat to the structural integrity of welded components. This work examines the softening and failure behavior of a 7050-T7451 hybrid laser welded joint. Nanoindentation test results show the FQZ to have the lowest hardness across the welded...