10.2514/6.2022-1427">
 

Testing and Characterization of Additive and Traditionally Manufactured Inconel 718 in a Combustion Materials Test Facility

Document Type

Conference Proceeding

Publication Date

1-2022

Abstract

For decades, nickel-based superalloys have been utilized for aerospace applications. Additive manufacturing is a growing trend in the aerospace industry since it provides a low-cost alternative for smaller volumes and complex designs. Additive manufactured nickel-based superalloys are now being considered as a replacement for traditionally manufactured components on commercial and military aircraft. While the potential of additive manufacturing for gas turbine engines is promising, the quality and performance of additive manufactured components still need to be extensively studied. Coupon-sized test specimens comprised of as-printed additive and traditionally manufactured Inconel 718 with and without yttria-stabilized zirconia thermal barrier coating were tested under simulated isothermal and thermal cycling combustion conditions that were representative of gas turbine environments. Microstructural characterization of pre- and post-test specimens with scanning electron microscopy and energy-dispersive X-ray spectrometry was carried out. Pre-test scanning electron microscopy indicated that traditionally manufactured coupons had a smooth surface finish with minor imperfections while as-printed additive manufactured coupons had a rough surface finish as expected. Post-test scanning electron microscopy exhibited differences in oxide scale between the isothermal and thermal cycling conditions. The thermal cycling condition increased the amount of oxide scale for both additive manufactured and traditional manufactured Inconel 718. The size of the oxide islands on traditionally manufactured coupons was significantly larger than the as-printed additive manufactured coupons. The results indicated that differences in surface roughness may affect the growth of oxidation scale in a high temperature combustion environment. The benefits of yttria-stabilized zirconia thermal barrier coating were characterized. The substrate of the coupons experienced little to no formation of oxide scales compared to the uncoated as-printed additive and traditionally manufactured coupons. The results further suggested that yttria-stabilized zirconia thermal barrier coating can be utilized to provide both insulation and oxidation protection when desired. Post-test energy-dispersive X-ray spectrometry results corresponded well with known elemental compositions and oxidation mechanisms.

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Source Publication

AIAA SCITECH 2022 Forum

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