Catalyst Project: Microstructural Evolution and Constitutive Modeling of Creep and Elevated Temperature Quasi-Static Tensile Deformation in Additively Manufactured Grade 91 Alloy

催化剂项目为历史上的黑人学院和大学（HBCU）提供支持，致力于建立教师的研究能力，以加强科学，技术，工程和数学（STEM）本科教育和研究。预计该奖项将进一步提高教师的研究能力，改善研究和教学机构，并参与本科生的研究经验。该奖项授予田纳西州立大学，支持教师和本科生在增材制造（AM）91级合金的现象学本构蠕变变形模型开发方面的研究经验。所提出的模型将提供对AM Grade 91合金在热变形过程中发生的冶金过程的本质的洞察，这将最终决定材料的机械行为。蠕变，在高同源温度下静态施加载荷下的时间依赖性变形是有害的，导致核，航空航天，和微电子工业。鉴于增材制造（AM）作为一种制造技术在许多行业中迅速发展，因此必须表征AM铁素体钢合金中的蠕变机制，这是AM文献或材料科学文献中尚未解决的主题。本研究的目的是研究AM铁素体91级钢合金的蠕变行为，这些合金是航空航天和核能工业中高温结构应用的潜在材料。对于本研究，试验载荷范围为100 MPa至300 MPa，试验温度范围为300 ℃至700 ℃。从蠕变应变对时间的曲线图获得的最小蠕变速率提供了抗蠕变性的量度。蠕变测试将与使用光学显微镜（OM），扫描电子显微镜（SEM），能量色散谱（EDS）和Rietveld细化的微观结构研究相结合，以深入了解控制AM铁素体91级钢蠕变的基本机制。这项研究的结果将有助于开发新一代抗蠕变高温合金，影响AM和材料科学，航空航天和核工程行业的学术界。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Catalyst Projects provide support for Historically Black Colleges and Universities (HBCU) to work towards establishing research capacity of faculty to strengthen science, technology, engineering, and mathematics (STEM) undergraduate education and research. It is expected that the award will further the faculty member's research capability, improve research and teaching at the institution, and involve undergraduate students in research experiences. This award to Tennessee State University supports faculty and undergraduate research experiences in the development of phenomenological constitutive creep deformation models for Additively manufactured (AM) Grade 91 alloy. The proposed models will provide insights into the nature of the metallurgical processes taking place during hot deformation processes in AM Grade 91 alloy, which will ultimately determine the mechanical behavior of the material.Creep, the time-dependent deformation under statically applied load at high homologous temperature is detrimental, resulting in catastrophic failures and/or substantially reduced life of critical structural components in nuclear, aerospace, and microelectronic industries. Given that additive manufacturing (AM) is proliferating as a manufacturing technique across many industries, it is imperative to characterize creep mechanisms in AM ferritic steel alloys, a topic that has not been addressed in either the AM literature or the materials science literature. The goal of this research is to study the creep behavior of AM ferritic grade 91 steel alloys which are potential materials for high-temperature structural applications in the aerospace and nuclear energy industries. For this study, the test loads will range from 100 MPa to 300 MPa, while the test temperatures will range from 300⁰C – 700⁰C. The minimum creep rates obtained from the plots of creep strain against time provides a measure of the creep resistance. Creep testing will be complimented with microstructural study using optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and Rietveld refinement to gain insight into the fundamental mechanisms that control creep in AM ferritic grade 91 steels. The results of this study will aid the development of new generation of creep resistant superalloys, impacting the scholarly communities of AM and materials science, aerospace, and nuclear engineering industries.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.