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

未来的清洁发电技术将需要先进的制造工艺，以便在当地快速生产高性能部件，以及由多样化和有效的工程师和技术人员组成的劳动力。基于自动金属弧焊的添加剂制造能够大规模和高速沉积，并有可能提供支持能源基础设施所需的灵活性和加速生产。然而，缺乏对加工条件如何影响材料的微观组织和高温机械性能的全面了解，以及是否需要后处理，阻碍了这种基于弧焊的添加剂制造在行业中的采用。该学院早期职业发展(CALEAR)奖支持一种综合的实验和建模方法，以开发添加剂制造期间的加工条件和所需的后处理之间的机械联系，以及决定与发电操作相关的高温蠕变和疲劳性能的关键微结构特征。该项目还将包括一个为少数人服务的两年期焊接技术计划，并开发一个教授焊接学徒各种形式自动化的模块，以及与科罗拉多矿业学院的工程专业学生共同开展的Capstone项目，该项目提供了一个独特的团队合作机会，相互欣赏互补的技能和专业知识。然后，自动化模块将与全国其他配对的2年制和4年制教育机构共享，以培养一支具有凝聚力的劳动力队伍，用于添加剂制造。这一教育努力将有助于建立一支更加多样化、灵活和有效的劳动力队伍，从而促进能源安全和国家的繁荣。总体研究目标是解决实现新兴清洁发电技术所需的具有挑战性的知识差距，包括工艺和材料工程。为了克服复杂性，项目组将对镍基高温合金Haynes 282的焊丝电弧添加剂制造过程中的工艺、显微组织和高温性能关系进行定量和机械性的了解。实验方法包括制备、原位热成像、热等静压、材料表征和各种力学测试，将结合分析和计算模型从根本上研究：(1)沉积条件对初生态组织和形貌的影响，(2)热等静压在控制晶粒度和形貌的同时减少缺陷的潜力，以及(3)微结构特征(由沉积和热等静压控制)对800-900摄氏度之间高温拉伸、疲劳和蠕变性能的影响，目标是苛刻的发电厂环境。该项目的成功完成将极大地推动极端服务条件下金属添加剂制造的科学发展。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

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.