Understanding Precipitation and the Mechanical Properties of Novel Laves Phase-Strengthened Austenitic Steels for Energy Applications

了解用于能源应用的新型 Laves 相强化奥氏体钢的析出和机械性能

• 批准号: 1206240
• 负责人: Ian Baker
• 金额: $ 40.5万
• 依托单位: Dartmouth College
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-09-01 至 2017-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1206240&HistoricalAwards=false
• 关键词: Understanding; Precipitation; Mechanical; Properties; Novel

TECHNICAL SUMMARYThis project aims to understand both the effects of deformation on the precipitation processes in Laves phase-strengthened austenitic steels, including determining the mechanism of NiAl co-precipitation, and how these two kinds of precipitates affect subsequent deformation processes. Thus, the proposed work will determine both the precipitation mechanisms and the interaction of gliding dislocations with these precipitates by performing annealing studies for a variety of times and temperatures, both with and without prior cold rolling, and both room-temperature tensile tests and elevated-temperature creep tests on these materials followed by post-mortem TEM examination. The fracture behavior will also be examined by performing in-situ straining studies at a variety of temperature in a scanning electron microscope. The orientation relationships between the phases both after various thermo-mechanical treatments and after creep deformation will be carefully studied using electron diffraction, while the microchemistry will be determined using both energy dispersive spectroscopy in the TEM and atom probe tomography. The precipitation processes and the deformation mechanisms will be further elucidated by performing in situ annealing studies and in situ straining studies in the TEM, respectively, at a variety of temperatures. The work will be performed by a Ph.D. student and several undergraduates.NON-TECHNICAL SUMMARYThe critical factor limiting the operation of power generation plants at higher temperatures is the lack of materials that are strong, corrosion resistant and economically viable. Operation at high temperature can lead to energy conversion efficiencies of 50%, which not only reduces running costs, but can also extend the lifetime of fossil fuels and/or reduce the carbon footprint of the plants. Unfortunately, currently-used steels cannot satisfy these requirements for higher operating temperatures. This project aims to determine the optimum processing condition and mechanical properties in new class of stainless steels strengthened with novel particles, and alloyed with aluminum for improved oxidation resistance. A Ph.D. student and several undergraduates are performing the work.

本项目旨在了解变形对Laves相强化奥氏体钢中沉淀过程的影响，包括确定NiAl共沉淀的机制，以及这两种沉淀物如何影响随后的变形过程。因此，拟议的工作将确定沉淀机制和滑移位错与这些沉淀物的相互作用，通过进行退火研究的各种时间和温度，既有和没有事先冷轧，和室温拉伸试验和高温蠕变试验，这些材料，然后通过事后TEM检查。还将通过在扫描电子显微镜中在各种温度下进行原位应变研究来检查断裂行为。 将使用电子衍射仔细研究各种热机械处理后和蠕变变形后的相之间的取向关系，同时将使用TEM和原子探针断层扫描中的能量色散谱来确定微观化学。 的沉淀过程和变形机制将进一步阐明通过执行原位退火研究和原位应变研究，分别在TEM中，在各种温度下。这项工作将由一位博士进行。非技术总结限制发电厂在高温下运行的关键因素是缺乏坚固、耐腐蚀和经济可行的材料。在高温下运行可以使能量转换效率达到50%，这不仅降低了运行成本，而且还可以延长化石燃料的使用寿命和/或减少工厂的碳足迹。 不幸的是，目前使用的钢不能满足更高操作温度的这些要求。 该项目旨在确定新型不锈钢的最佳加工条件和机械性能，这些不锈钢采用新型颗粒强化，并与铝合金化以提高抗氧化性。博士学位学生和几个本科生正在做这项工作。