CAREER: Understanding Microstructure Evolution and Mechanical Properties of High-rate Additively Deposited Nickel-based Superalloy to Enable Future Clean-energy Manufacturing

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Future clean power generation technologies will require advanced manufacturing processes to produce high-performance components locally and swiftly as well as by a diverse and effective workforce of both engineers and technicians. Additive manufacturing based on automated metal arc welding is capable of large-scale and high-rate depositions and has the potential to provide flexibility and accelerated production needed to support the energy infrastructure. However, the lack of a comprehensive understanding of how processing conditions affect the material's microstructures and the high-temperature mechanical properties and if post-processing is needed, hinders the adoption of such arc-welding based additive manufacturing in the industry. This Faculty Early Career Development (CAREER) award supports an integrated experimental and modeling approach to develop a mechanistic link between processing conditions, during additive manufacturing and required post-processing, and crucial microstructural features that dictate high-temperature creep and fatigue performance relevant to power generation operations. The project will also involve a minority-serving 2-year welding technology program and develop a module that teaches welding apprentices with various forms of automation, plus a joint capstone project with engineering students from the Colorado School of Mines, which provides a unique opportunity of team working with mutual appreciation of complementary skills and expertise. The automation module will then be shared with other paired 2-year and 4-year educational institutes around the country to develop a cohesive workforce for additive manufacturing. This educational endeavor will contribute to a more diverse, agile, and effective workforce, thus promoting the energy security and Nation’s prosperity.The overall research objective is to address the challenging knowledge gaps, in both process and materials engineering, needed to realize emerging clean power generation technologies. To overcome the complexity, the project team will develop a quantitative and mechanistic understanding of the processing, microstructures, and high temperature property relationships in wire arc additive manufacturing of a nickel-based superalloy, i.e., Haynes 282. Experimental methods including fabrications, in-situ thermal imaging, hot isostatic pressing, material characterizations and various mechanical testing will be combined with analytical and computational models to fundamentally investigate: (1) influence of deposition conditions to as-build microstructures and morphology, (2) potential of hot isostatic pressing to simultaneously reduce defects while controlling the grain size and morphology, and (3) effects of microstructure characteristics (controlled by deposition and hot isostatic pressing) on high-temperature tensile, fatigue, and creep performance between 800 and 900 Celsius, targeting demanding severe power plant environments. The successful completion of this project will substantially advance the science of metal additive manufacturing for extreme service conditions.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.