A review on formation and suppression mechanisms of porosity and cracks in wire arc-directed energy deposition Al-Zn-Mg-Cu alloys

Abstract

With the rapid development of the manufacturing industry, wire arc-directed energy deposition, as an emerging manufacturing technology in recent decades, has become the hot focus of attention of an increasing number of researchers. Influenced by the high solubility of hydrogen in aluminum alloys and the formation of low-melting-point eutectics during the deposition process of Al-Zn-Mg-Cu alloys, porosities and cracks are likely to occur in the deposited parts, which directly and severely reduces mechanical properties. The characteristics and advantages of wire arc-directed energy deposition, as well as the process characteristics under different heat sources, were summarized and analyzed in this work. It was focused on elaborating the mechanisms of porosity and crack formation during wire arc-directed energy deposition of Al-Zn-Mg-Cu alloys. The cutting-edge methods that have been adopted by researchers in recent years to reduce and suppress metallurgical defects were also introduced. In terms of suppressing pores, plastic deformation methods represented by interlayer rolling and the application of external fields can be used to reduce the density of hydrogen pores. Moreover, the crack susceptibility of Al-Zn-Mg-Cu alloys can also be reduced by means such as adding other elements to generate nano-phase particles. Finally, an insightful outlook and summary of the possible future research paths and exploration directions of wire arc-directed energy deposition of Al-Zn-Mg-Cu alloys is provided.