Nickel based super alloy, INCONEL 718, is known for its strength, creep resistance, fatigue life, high temperature oxidation resistance, and corrosion resistance to aggressive aqueous environments. As a γ’ and γ’’ precipitation strengthened alloy, a number of compositional modifications through alloying elements are made in this material for improving its environmental degradation resistance. Electrochemical corrosion of Ni based super alloys, in particular, poses continuous challenges, for improving service life, due to variety of harsh environments, the structural components constituting these alloys are exposed to, especially in aeroengines & chemical processing plants. Selective laser melting (SLM), a metal additive manufacturing technique, has been widely accepted as a potential technique in the industry for producing complex geometry of structural components using this alloy, due to various advantages it offers such as geometric freedom, reduced processing time, and reduced wastage in addition to improved corrosion resistance achievable through effective microstructural engineering of the alloy.
The presentation is focused on literature review, identification of research gap, objectives, and preliminary work carried out so far. There are no systematic attempts made so far for understanding environmental degradation mechanisms of Ni based super alloy fabricated through SLM. Therefore, in the present work, INCONEL 718 alloy was fabricated using optimized process parameters in SLM technique. The as built samples are subjected to post processing treatments such as shot peening and heat treatment to study its influence on the microstructural evolution and degradation rate in aggressive environment. Surface roughness measurements were made on the as- built and post processed specimens. It was found that shot peening led to smoothening of surface morphology of processed samples when compared to the as built samples. Optical microscopic imaging of as built and post-processed INCONEL 718 was performed to characterize the features such as melt pool tracks, hatch patterns, mesostructure evolution of three planes comprising the specimen geometry. Scanning Electron Microscopic imaging of processed samples was carried out to characterize the morphological features of different phases and precipitates formed during deposition. The degradation behavior of a selective laser melted INCONEL 718 alloy, in as built and post processed condition exposed to aggressive medium will be investigated as a continuation of the proposed work. Furthermore, adoption of Machine learning (ML) based techniques, for prediction of a corrosion rate in the same alloy will be discussed.