微粒子喷丸-微弧氧化复合处理高速接触网腕臂铝合金超高周疲劳破坏机理及寿命预测

我国高速铁路已取得举世瞩目的飞速发展，但是，随着高铁开通里程和运营时间的增加，高速接触网腕臂铝合金构件出现破坏的现象时有发生。这是由于国产腕臂构件制造技术自国外引进，而其自主化和性能提升研究却相对滞后。本研究针对接触网腕臂Al-Si-Mg合金开展微粒子喷丸-微弧氧化复合处理，分析处理后表面性能演变，研究复合处理工艺参数和表面性能关系；开展超高周疲劳试验，研究复合处理工艺对超高周疲劳性能和破坏行为影响，确定与腕臂铝合金抗超高周疲劳相匹配的复合处理工艺参数，同时，基于同步辐射光源开展超高周疲劳试验，研究疲劳裂纹萌生和扩展过程，并结合裂纹萌生位置和扩展路径的微观组织分析，阐明超高周疲劳破坏机理；此外，结合疲劳断口形貌分析，建立考虑表面性能演变和内部微观组织特性的超高周疲劳寿命预测模型。本研究可以为国产高速接触网构件性能提升表面处理工艺选择、抗超高周疲劳可靠性设计和运营维护策略制定提供依据。

In China the high-speed railway has made remarkable development, but with the increase of the opening mileage and operation time, the damage of cantilever components made of aluminum alloy in high-speed railway catenary system occurs from occasionally. This is because the manufacturing technology of the catenary components is introduced from abroad, and the research on its localized production and performance improvement is comparatively lagging. In this study, the Al-Si-Mg alloy applied to the catenary cantilever is treated by the combined treatment of micro-shot peening and micro-arc oxidation. The surface property evolution after the treatment is analyzed and the relationship between combined treatment process parameters and surface properties is studied. The very high cycle fatigue tests are conducted and the effect of combined treatment on very high cycle fatigue properties and fracture behaviors are investigated, meanwhile, the combined treatment parameters matching with the aluminum alloy to improve the very high cycle fatigue property is determined. At the same time, the synchrotron very high cycle fatigue tests are carried out to investigate the crack initiation and propagation process. According to the test results and the microstructure analysis on crack initiation site and extension path, the fracture mechanism in the very high cycle regime is clarified. In addition, based on the analysis of fatigue fracture morphology, a life prediction model for very high cycle fatigue considering the evolution of surface properties and microstructure characteristics is established. The results of this study can provide guidance for the selection of surface treatment technology for the performance improvement of localization high-speed railway catenary cantilever components, the reliability design for anti-very-high cycle fatigue and the formulation of operation and maintenance strategies.