Friction stir welding of wire arc additively manufactured 205A aluminum alloy: Microstructure and mechanical properties.

Friction stir welding (FSW) was used to weld the 205 A aluminum alloy parts fabricated by wire arc additive manufacturing (WAAM). The microstructure characteristic, phase structure and dislocation were systematically investigated, and the mechanical properties of the FSW joint were evaluated. The results show that the pores in the weld were almost eliminated, and the fine recrystallized grains with a size of about 5 μm were obtained in the stir zone. Under the effects of severe plastic deformation and heat, the θ phases were broken and partially dissolved in the weld during the FSW process, and the θ′ strengthening phases were precipitated by the promotion of Cd. Compared to the WAAM-fabricated 205 A base material, the FSW joint maintained high strength and improved plasticity because of the precipitation strengthening of θ′ phases and the grain boundary strengthening of fine recrystallized grains. • The WAAM-fabricated 205 A aluminum parts were first welded by FSW. • θ′ phases were precipitated in the weld promoted by Cd element. • The mechanical properties of the FSW joint were better than BM. • The strength was improved by the θ′ phases and fine recrystallized grains. [ABSTRACT FROM AUTHOR]