Mechanical properties and precipitation behavior of the heat-treated wire + arc additively manufactured 2219 aluminum alloy

The dense 2219 Al alloy was successfully fabricated by the Wire + Arc additive manufacturing (WAAM) technology. It was subsequently processed through solution and aging (T6) heat treatment to improve its performance. There were some θ' phase precipitated because of the thermal cycling during the WAAM forming process. Then, the supersaturation of copper in the α-Al matrix was reduced. The influence of solution temperature on the precipitation behavior of the θ″ phase and the microstructure evolution were investigated in detail. The experimental and calculative results demonstrate that the precipitation strengthening of the θ″ phase improves with the increasing solution temperature, and the strengthening contribution of θ″ phase is 202.1 MPa, 165.2 MPa, and 150.3 MPa corresponding to the solution temperature at 540 °C, 530 °C, and 520 °C, respectively. The average ultimate tensile strength, yield strength, elongation, and micro-hardness of the WAAM processed samples were obtained after T6 treatment with 540 °C, 45 min/Water quenching +180 °C, 6 h/Water quenching, which is 397 ± 4 MPa, 303 ± 5 MPa, 5.3 ± 1%, and 139 ± 6 HV respectively. Compared to the casting + T6 treated 2219 Al alloy, the samples in this research present a similar tensile strength and slightly lower ductility.