高速轮轨钢超声振动辅助激光熔覆涂层的滚动摩擦磨损性能

Rolling Contact Wear Properties of Ultrasonic Vibration Assisted Laser Cladding Coating on High-Speed Wheel/Rail Steel

目前有关高速轮轨钢超声振动辅助下的激光熔覆研究鲜有报道。在高速轮轨钢表面施加超声振动辅助激光熔覆制备了铁钴基复合涂层来改善其耐磨性能,借助扫描电镜(SEM)、X射线衍射仪(XRD)、能量色散谱仪(EDS)等手段分析熔覆层的微观结构、物相成分和元素分布,采用GPM-30轮轨滚动接触疲劳试验机对比研究轮轨钢超声振动辅助作用下激光熔覆前后涂层的滚动摩擦磨损性能。结果表明:熔覆层主要由Fe-Cr的马氏体组织、Co-Cr的γ相固溶体、Fe-Ni固溶体以及弥散析出的含MxCy(M=Cr、W)的碳化物、硼化物、硅化物等硬质相组成;超声激光熔覆强化处理后,轮轨表面的平均显微硬度分别为539 HV3 N和582 HV3 N,磨损速率分别降低59.1%,37.3%,轮轨试环熔覆层的抗磨损性能大幅提高,磨损机制由剥落磨损和严重的疲劳磨损转变为轻微的磨粒磨损和疲劳磨损。

Fe-Co-based composite coatings on high-speed wheel/rail steel by ultrasonic vibration assisted laser cladding were prepared to improve the wear resistance. The morphology,phase composition and element distribution of cladding coatings were characterized by scanning electron microscopy( SEM),X-ray diffractometer( XRD) and energy dispersion spectrum( EDS),respectively. The rolling contact friction and wear behaviors of cladding coating before and after laser cladding assisted by ultrasonic vibration on wheel/rail steel were evaluated by wheel/rail rolling contact fatigue tester. Results showed that the as-obtained cladding coating was mainly consisted of Fe-Cr martensite microstructure,Fe-Ni and γ phase Co-Cr solid solution as well as dispersed MxCy( M=Cr,Ni) carbide,boride and silicious hard phase. The wheel steel and rail steel undergoing laser cladding showed average surface hardness of 539 HV3 Nand 582 HV3 N,and the wear rates decreased by 59.1% and 37.3%,respectively. Furthermore,the wear resistance of the cladding layer on wheel/rail discs could be greatly improved,and the wear mechanism of wheel/rail discs changed from spalling damage and serious fatigue wear into light abrasive wear and fatigue wear.