Research progress on wire arc additive manufactured Al-Zn-Mg-Cu alloys: Metallurgical defects, refining grains, enhancing mechanical properties

• A comprehensive review on metallurgical defects, refining grains and enhancing properties of WAAM Al-Zn-Mg-Cu alloys was provided. • The forming mechanism of metallurgical defects of WAAM Al-Zn-Mg-Cu alloys was analyzed and strategies were proposed. • The future research and development direction of WAAM Al-Zn-Mg-Cu alloys is prospected. Wire arc additive manufacturing (WAAM) of Al-Zn-Mg-Cu alloys is a hot topic of current research in the field of additive manufacturing. Microstructure and properties related issues of wire arc additive manufactured Al-Zn-Mg-Cu alloys attracted more and more attentions from researchers around the world, which mainly includes metallurgical defect issues, refining grains, enhancing mechanical properties. Due to the unique properties of Al-Zn-Mg-Cu alloys and the characteristics of the WAAM process, a large number of pores and cracks are very likely to appear during the fabrication process, and the properties of the manufactured parts cannot meet the actual demand. However, if the metallurgical defects in the workpiece can be eliminated in a reasonable way, grain refinement can be achieved, and the mechanical properties of the material can be enhanced, the wire arc additive manufactured Al-Zn-Mg-Cu alloys can be used in many special service scenarios. In this paper, the progress of research on WAAM Al-Zn-Mg-Cu alloys is reviewed, aiming to provide ideas to reduce metallurgical defects, refine grains and enhance mechanical properties of WAAM Al-Zn-Mg-Cu alloys.