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Concurrent Enhancement of Fatigue Life and Corrosion Resistance via Laser Shock Peening

通过激光冲击强化同时提高疲劳寿命和耐腐蚀性

基本信息

批准号：
1761344
负责人：
Y Lawrence Yao
金额：
$ 36.63万
依托单位：
Columbia University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2018
资助国家：
美国
起止时间：
2018-09-01 至 2022-08-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1761344&HistoricalAwards=false
关键词：
Concurrent Enhancement Fatigue Life Corrosion

项目摘要

This research project addresses the fundamental science associated with surface deformations induced by laser shock peening (LSP), and their use to improve the stress corrosion cracking (SCC) resistance of metallic components in addition to LSP's well-known effect on fatigue life. SCC is a phenomenon where the combination of a tensile load in a corrosive environment causes premature failure. This failure is often sudden, catastrophic and occurs at loading levels far below a material's yield strength, making it difficult to predict. Depending on the material and environment, SCC can occur through different mechanisms, thus there is a need to identify mitigation approaches. Shockwaves generated on the surface using LSP impart compressive residual stresses, without thermal effects, and have traditionally been used to improve the material's fatigue life. They also induce other changes at the microstructural level, which may help mitigate SCC concurrently. Improving material performance will enhance the capability of existing technologies, potentially by allowing them to operate at higher tensile loads for longer times. In addition, the surface treatment methodology can be applied to different materials and geometric configurations, thus providing effective solutions for many industries ranging from nuclear reactors to oil production to medical devices. As such, the research has significant breadth and directly and positively impacts economic welfare and national security. By networking with minority groups such as National Society of Black Engineers, underrepresented students will be recruited. High school students and STEM teachers from neighborhood schools in northern Manhattan and the Bronx will be engaged in an innovative combination of "reach out" and "let in" activities.This project will set forth the mechanisms that allow deformation processes to have stress corrosion cracking (SCC) mitigation benefits. Fundamental understanding of the interaction between the shockwave-induced microstructural changes and the SCC pathways will be developed. Hydrogen has been identified as a major component driving SCC, and thus entry of hydrogen into the surface and propagation of absorbed hydrogen within the lattice will be better understood. Movement of mobile dislocations can contribute to crack propagation. Both of these components will be influenced by dislocation cell structures formed during shockwave processing. In addition, the electrochemical effects of the deformation process on SCC and their mitigation will be studies in a fundamental approach. Finally the project will perform scientific investigation into the balance between LSP's effect on fatigue life and SCC resistance.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.

这项研究项目涉及激光冲击喷丸(LSP)引起的表面变形的相关基础科学，以及它们在提高金属部件的抗应力腐蚀破裂(SCC)方面的应用，以及LSP对疲劳寿命的众所周知的影响。应力腐蚀开裂是指在腐蚀性环境中，拉伸载荷的组合导致过早失效的现象。这种失效通常是突然的、灾难性的，并且发生在远低于材料屈服强度的加载水平，因此很难预测。根据材料和环境的不同，应力腐蚀可以通过不同的机制发生，因此需要确定缓解方法。使用LSP在表面产生的冲击波产生压缩残余应力，没有热效应，传统上被用来提高材料的疲劳寿命。它们还在微观结构水平上引发其他变化，这可能有助于同时缓解SCC。材料性能的改进将增强现有技术的能力，潜在地允许它们在更高的拉伸载荷下运行更长时间。此外，表面处理方法可以应用于不同的材料和几何构型，从而为从核反应堆到石油生产再到医疗器械的许多行业提供有效的解决方案。因此，这项研究具有重大的广度，并直接和积极地影响经济福利和国家安全。通过与全国黑人工程师协会等少数群体建立联系，将招收代表人数不足的学生。来自曼哈顿北部和布朗克斯区社区学校的高中生和STEM教师将参与一项创新的组合活动，即“向外伸展”和“向内伸展”。该项目将阐述允许变形过程具有缓解应力腐蚀开裂(SCC)益处的机制。我们将对冲击波引起的微结构变化和SCC途径之间的相互作用有一个基本的了解。氢已被确定为驱动应力腐蚀开裂的主要成分，因此将更好地理解氢进入表面和吸收的氢在晶格内的传播。移动位错的运动有助于裂纹的扩展。这两种成分都会受到冲击波处理过程中形成的位错晶胞结构的影响。此外，将从根本上研究变形过程对应力腐蚀开裂的电化学影响及其缓解。最后，该项目将对LSP对疲劳寿命的影响和抗SCC性能之间的平衡进行科学调查。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。