Advanced Manufacturing and Post-Processing of Haynes 282 for High-Temperature Performance Applications

Additive manufacturing (AM) has been used to produce nickel-based superalloys, such as Haynes-282, for high-temperature/performance applications, including space and aerospace engines and turbine components, as well as power generation components. Some benefits of AM include reduced manufacturing time and cost due to part consolidation, as well as improved part lightweighting that can, in turn, yield improvements in part performance and reduced deployment times and operation/maintenance costs. An alloy of significant interest to the Air Force as well as the aerospace industry is the Haynes® 282® (H-282) due to its exceptional high-temperature properties with excellent creep strength at temperatures as high as 900 oC (1,600 oF). Nonetheless, successfully implementing AM H-282 in their as-build conditions remains a challenge due to the surface roughness and the presence of near-surface defects, often resulting in hampered performance and reliability. To overcome these limitations, this Phase I effort will prove the feasibility of two chemical-based technologies to improve the surface roughness of AM H-282 components. The proposed surface finishing process for the components are: (1) chemical polishing (CP) and (2) chemical-mechanical polishing (CMP) to improve the surface quality and mechanical properties of AM H-282. The CP process removes surface and near-surface defects, producing a surface roughness (Ra) of ~1 µm, keeping dimensional accuracy, and capable of finishing, cleaning, and even declogging internal channels. The CMP process applied after CP can potentially achieve surface roughness in the submicron ranges (Ra < 0.1 µm). However, it can be employed independently of CP and produce significantly smooth surfaces on external surfaces. The expected results are to show that the combination of CP and CMP will significantly improve the surface roughness of the PBF-LB/H-282 components, making them suitable for use by the US Air Force. Moreover, due to the intrinsic characteristics of AM, such as high cooling rates, the microstructure of AM H-282 is unique, and can be tuned with further heat treatments (HT) such as: stress relief (SR), solution annealing (SA), and aging (SA), and hot isostatic pressing (HIP), which can substantially affect the tensile and fatigue properties. We propose to determine the synergistic effects of surface finishing on AM H-282 in combination with the different metallographic structures that can be achieved through the three reported HTs studied in the literature. The outcome will build confidence to implement AM H-282 on critical flight components to fulfill the USAF needs and to the commercial user to implement the technology.