Gu, JianglongGao, MinjieYang, ShouliangBai, JingZhai, YuchunDing, Jialuo2020-02-032020-02-032019-11-13Gu J, Gao M, Yang S, et al., (2020) Microstructure, defects, and mechanical properties of wire + arc additively manufactured AlCu4.3-Mg1.5 alloy. Materials and Design, Volume 186, January 2020, Article number 1083570264-1275https://doi.org/10.1016/j.matdes.2019.108357https://dspace.lib.cranfield.ac.uk/handle/1826/15080The wire with a composition of AlCu4.3%Mg1.5% was customized and used to deposit the WAAM alloy with the power source of cold metal transfer. The microstructure, defect, and mechanical properties of the as-deposited and heat-treated WAAM alloys were studied. Key findings demonstrated that the microstructure of the as-deposited alloy was characterized by a hierarchical distribution of dendrites, equiaxed grains, and a slight number of columnar grains. The volume fraction of the network-like scattered coarse particles of second phases θ + S reduced by 95% after the T6 heat treatment. With an average microhardness of 161.4 HV, the mean yield strength and ultimate tensile strength of the WAAM alloy increased by 116% and 66% achieving 399 MPa and 485 MPa in the horizontal direction after heat treatment. The precipitation of a high density of needle-shaped metastable S′ precipitates was responsible for the significantly enhanced mechanical properties. However, this WAAM alloy has exhibited an anisotropic tensile property. A considerable number of sharp-angled defects like linear and chain-like micropores, which generally depress the mechanical properties, were formed in the WAAM alloys.enAttribution-NonCommercial-NoDerivatives 4.0 Internationalhttp://creativecommons.org/licenses/by-nc-nd/4.0/Wire + arc additive manufacturingAl alloyAl-Cu-MgMicrostructureDefectMechanical propertyArticle