激光熔覆在高速列车上的应用研究现状

高速列车轮轨、制动盘、车轴是易发生磨损的部件，采用激光熔覆技术能有效改善磨损或对损伤部件进行修复。综述了激光熔覆应用于高速列车轮轨、制动盘、车轴的研究现状。归纳了现有研究中各部件所采用的熔覆材料。总结了不同部件所关注的性能，针对不同部件的特性，分析了其对激光熔覆层性能的需求和应采用的熔覆层性能测试方法。对于列车轮轨，旨在通过激光熔覆涂层提高其接触面抗磨损和抗滚动接触疲劳性能；对于制动盘，旨在通过涂层减小其摩擦磨损和热疲劳；对于车轴可采用激光熔覆技术对已损伤的部位进行修复，并应重点关注车轴修复后的疲劳性能。此外，提出了激光熔覆实际应用于高速列车部件上现存的几个关键问题，包括：激光熔覆热影响区组织对部件服役性能的影响；激光熔覆残余应力的影响；激光熔覆低效率和高稀释率的问题；激光熔覆组件热损伤问题。目前的研究主要集中于激光熔覆材料的选择和性能评价，而从组织演变、残余应力及服役性能三者综合考虑的轨道交通理论基础有待构建。

Application Status of Laser Cladding in High-speed Trains

The components of high-speed trains, such as wheels, rails, brake discs, and axles, are prone to wear. Laser cladding is an effective way to reduce wear and repair damaged parts. The application status of laser cladding in such components was reviewed. The cladding materials used for various components in the current study were summarized. The performance of different components was summarized. According to the characteristics of different components, the requirements of components for laser cladding performance and the testing methods of cladding performance were analyzed. As for wheels and rails, the cladding layer aimed to improve the wear resistance and anti-rolling contact fatigue performance of the contact surface. As for brake discs, the cladding layer aimed to reduce friction, wear and thermal fatigue. Finally, laser cladding was used to repair the damaged parts of the axle, and the fatigue performance of the repaired axle was emphasized. Several key issues of the practical application of laser cladding in high-speed train components were put forward, including effect of heat-affected zone on the service performance of components, effect of residual stress, low efficiency and high dilution rate of laser cladding and thermal damage of laser cladded components. The current research mainly focuses on the material selection and performance testing of the cladding layer. The theoretical basis for each component considering the structure evolution, residual stress and service performance needs to be established.