环境影响下的多尺度轻金属合金高周疲劳失效机理及对策研究

项目名称： 环境影响下的多尺度轻金属合金高周疲劳失效机理及对策研究

项目编号： No.11272173

项目类型： 面上项目

立项/批准年度： 2013

项目学科： 数理科学和化学

项目作者： 王习术

作者单位： 清华大学

项目金额： 96万元

中文摘要： 环境腐蚀是降低金属强度的一个不争事实，水（油）对轻金属材料的疲劳强度在高周或超高周中的劣化也有较强的影响；另一方面，研究表明2024铝合金表面的微氧弧涂层对疲劳性能则有增强的效果。然而这些工作对其疲劳劣化或增强形成机制尚缺乏清晰、翔实的实验证据，更缺乏足够的微观变形、断裂的实验观察和理论分析。因此，基于我国现有环境特点，选择抗腐蚀能力差的铝、镁合金材料，在多场(力-热-腐蚀)、多尺度下对其疲劳失效机理开展研究，寻找一种合理的微氧弧涂层厚度提高其抗疲劳能力。研究分为：微观尺度-用SEM原位试验方法针对高周疲劳失效机制，研究不同湿度、不同油成分对上述合金疲劳微裂纹萌生与扩展行为定量表征，得到其疲劳裂纹扩展速率方程式为预测其寿命提高一种方法；宏观尺度-用带腐蚀系统的旋转弯曲实验法研究循环次数为10E(7-8),不同微氧弧涂层厚度抵抗环境影响下材料的疲劳寿命增强行为及表征，提出合理的涂层厚度依据。

中文关键词： 铝合金；环境介质；高周疲劳；失效机理；对策研究

英文摘要： It is a fact for the environmental corrosion on the strength degradation of metal, such as the effect of water humidity and oil component on the high cycle or super high cycle fatigue strength of light metals can not ignored. To avid the corrosion fatigue damage of light metals, it is one of effective methods that is a smear layer on the surface of light metals. The emphasis of the present work is to investigate the behaviors and characteristics of enhanced strength for the light metals in the high cyclic fatigue (HCF) (10E7-10E8) failure under the different environmental water humidity and oil components by using the dual-spindle rotating bending fatigue testing machine, which include to the compared with the difference of S-N curves for the samples with the different smear layer thicknesses. On the other hand, the emphasis of the present work is to investigate the mechanism of fatigue micro crack initiation and propagation behavior of light metals at the different loading-thermal-corrosion states by using scanning electron microscope (SEM) in-situ observation including to explaining how the corrosion micro defects and interface micro crack are evolved in local stress or strain concentration by experimental observations and finite element analysis (FEA). At the same time, the effects of different environmental

英文关键词： Aluminum alloys；Environmental media；High-cyclic fatigue；failure mechanism；preventive method