A critical review of wire arc additive manufacturing of nickel-based alloys: principles, process parameters, microstructure, mechanical properties, heat treatment effects, and defects

Wire arc additive manufacturing (WAAM) is capable of fabricating medium-to-large-scale parts due to its higher deposition rates. The mechanical and metallurgical characteristics of WAAMed parts are better compared to other additive manufacturing techniques. Since the technology has grown, a wide range of metals are processed by WAAM in recent days. Nickel (Ni)-based superalloys are superior in terms of oxidation resistance, high-temperature mechanical performance, and microstructural characteristics. The selection of WAAM techniques, input parameters, resulting microstructure, post-processing treatments, and the defects can influence the final mechanical properties. The WAAMed Ni-based superalloys show inhomogeneous microstructure and mechanical properties from bottom to top layers. To obtain the homogeneous and improved mechanical properties, still there is a strong need to understand the underlying physical metallurgical mechanisms. In this context, this paper reports a present-day review on the process parameters, microstructural characteristics, mechanical properties, corrosion behaviour, and defects of WAAMed Ni-based superalloys. Adapting the strategies like interpass cooling, post-deposition heat treatment, and solution annealing improves the mechanical properties and can help to obtain homogeneous characteristics. More penetrative research works should be carried out to analyse fatigue and corrosion properties of WAAMed Ni-based superalloys for future industrial applications. Additionally, process parameters optimization and better control over quality are the other aspects to be focused by further studies.