Research progress in wire-arc additive manufacturing of 7××× aluminum alloys

High-strength 7××× aluminum alloys are widely used in aerospace, automotive and other fields due to their excellent mechanical properties. Traditional manufacturing technologies have been difficult to meet the demand for high efficiency and low cost manufacturing of large size and complex 7××× aluminum alloys parts.As an emerging metal additive manufacturing technology, Wire-Arc Additive Manufacturing（WAAM） provides a new idea for the preparation of large size complex 7××× aluminum alloys components for aerospace. However,the 7××× aluminum alloys components fabricated by WAAM still suffer from microstructure inhomogeneous,numerous pores, and anisotropic mechanical properties, which limit their wide applications. Firstly, the paper describes the principles and characteristics of different WAAM processes, and discusses the formation mechanisms and control strategies of defects such as microcracks and porosity. The evolution of the microstructure of the deposited alloys and its relationship with the mechanical properties are discussed, and the corresponding control methods are proposed. In addition, the effects of post treatment processes such as heat treatment and Laser Shock Peening on the microstructure and mechanical properties are also discussed. Finally, the future development trend and research direction of high strength 7××× aluminum alloys parts fabricated by WAAM are prospected.