An overview of Ni-based superalloy 718 fabricated via arc-based directed energy deposition
Francisco Werley Cipriano Farias, Valdemar R. Duarte, João da Cruz Payão Filho, Telmo G. Santos, J.P. Oliveira
Abstract
The age-hardened Ni-based superalloy 718 (UNS N07718; Inconel® 718) is recognized for its high cost, low machinability, and good weldability, making it suitable for additive manufacturing, particularly arc-based directed energy deposition (DED) processes. However, due to its coarse and highly oriented microstructure, interdendritic segregation of alloying elements (e.g., Nb and Mo), and the presence of deleterious second phases (e.g., Laves and MC-type carbides), Inconel® 718 fabricated via arc-based DED generally exhibits a low response to post-deposition heat treatment. As a result, it often fails to meet typical material specifications (e.g., AMS 5662) and corrosion resistance criteria, limiting its use in mission-critical applications such as the aerospace, defense, and energy industries. In this context, the present review critically examines the limitations, potential benefits, and processing conditions associated with Inconel® 718 fabricated via arc-based DED, surveying the existing body of research on this material. Thus, the microstructure, heat treatment response, mechanical properties, and printability of arc-based DED Inconel® 718 are comprehensively discussed and correlated with the metallurgical and process characteristics.