Selection and performance of AM superalloys for high-speed flight environments

Abstract

In developing the Wire + Arc Additive Manufacturing (WAAM) process for the manufacture of components used in high-speed flight environments, a selection process for suitable alloys was devised. Using material properties from literature sources, creep-resistant alloys were down-selected based on the requirement for service in a high temperature, high stress environment and the need for an alloy suitable for manufacture using the WAAM process. Down-selected alloys, Inconel 718 (IN718), Rene 41 (RE41), Haynes 188 (H188) and Inconel 625 (IN625), were deposited by a plasma transferred arc WAAM process in an oxygen-controlled environment. Wall structures were built, and samples extracted for mechanical testing. The performance of as-deposited material was then compared against the wrought literature data. Tensile testing at room temperature revealed a performance mismatch, in comparison with wrought literature data, for precipitation strengthened IN718 & RE41; however, this performance mismatch was less significant for solution strengthened H188 and IN625. Results revealed that the AM material did not meet the wrought strength with performance varying depending on each alloy’s strengthening mechanism. Results illustrate the need for further processing to return the mechanical performance to wrought values.