Microstructure and mechanical properties of Al-Zn-Mg-Cu alloy fabricated by wire + arc additive manufacturing

ER5356, ER2319, and Zn welding wires were synchronously fed by a GTAW wire + arc additive manufacturing (WAAM) system, and the microstructure and mechanical properties of the deposited Al-Zn-Mg-Cu aluminum alloy components were investigated. The results showed that the phase composition of WAAM 7050 alloy is mainly composed of α-Al, S (Al2CuMg), η (MgZn2), and θ (CuAl2) phases. The composition of each element is in accordance with the intended design and the specifications of the 7050 aluminum alloy composition. The lower portion of each deposited layer is mainly composed of columnar crystals, and the upper portion exhibits an equiaxed crystal structure. A small number of defects, such as pores and microcracks, were observed in the interlayer. The average hardness of the components was 106 HV; the tensile strength is 241 MPa in the horizontal direction and 160 MPa in the vertical direction. The fractographs exhibited typical brittle fracture characteristics. The reasons for the anisotropy of its mechanical properties were explained in detail.