Minimizing porosity and optimizing microstructure of hot-wire arc additive manufactured Al-Cu-Mg-Ag alloy for strength increment

Here, wire arc additive manufacturing (WAAM) is employed for the fabrication of Al-Cu-Mg-Ag alloy, focusing on improving mechanical property via eliminating porosity and tuning microstructures. Via optimizing the hot-wire current and pulse frequency of WAAM, the volume fraction of porosity reduces from 3.13 % to 1.77 %, along with grain refinement. Overhigh pulse frequency leads to lower sphericity of pores and larger grain size. Finite element analysis performed by Abaqus software reveals that both ultimate tensile strength (UTS) and elongation decrease with higher volume fraction of porosity, and large pores are the preferential sites of strain concentration, crack initialization and final fracture. Based on the optimization of WAAM processing parameters, a WAAM-customized T6 temper is proposed for the Al-Cu-Mg-Ag alloy, to enable the formation of strengthening Ω precipitates. Resultantly, UTS and yield strength (YS) reach 425.2 ± 6.0 MPa and 400.3 ± 4.6 MPa, respectively, which increased by 42.6 % and 111.2 % compared with as-deposited alloy.