Investigations on weld joints of 7075 alloy with Al–5Mg–1Zn composite fillers by arc welding

Abstract

In this work, the semisolid stirring casting assisted ultrasonic treatment and multi-pass rolling methods were applied to fabricate TiCp/Al–5Mg–1Zn filler materials for tungsten inert gas welding of 7075-T651 aluminum alloy. After welding, various performances and microstructures of the as-weld samples were studied via multifarious electron microscopy and extensive tests. As a result, the TiC nanoparticles which distributed uniformly minished the size of α-Al grains and modified secondary phase owing to the heterogeneous nucleation and retardation of growth. The hardness and tensile strength of joints were enhanced as TiC particles were added, compared to those of 5183 commercial fillers. Besides, both the stress corrosion cracking and intergranular corrosion susceptibility of the weld joints were reduced.