钢轨材料局部激光熔覆自熔性合金涂层的磨损与滚动接触疲劳行为  

Wear and Rolling Contact Fatigue Behavior of Locally Laser Cladded Rail Material Using Self-fusible Alloy

作　　者：丁昊昊[1] 谢天星 王文健[1] 祝毅[2] 阳义 郭俊[1] 林强[1] DING Haohao;XIE Tianxing;WANG Wenjian;ZHU Yi;YANG Yi;GUO Jun;LIN Qiang(State Key Laboratory of Rail Transit Vehicle System,Southwest Jiaotong University,Chengdu 610031,China;State Key Laboratory of Fluid Power and Mechatronic Systems,Zhejiang University,Hangzhou 310027,China;Chengdu Qingshi Laser Technology Co.,Ltd.,Chengdu 610213,China)

机构地区：[1]西南交通大学轨道交通运载系统全国重点实验室,成都610031 [2]浙江大学流体动力与机电系统国家重点实验室,杭州310027 [3]成都青石激光科技有限公司,成都610213

出　　处：《中国表面工程》2024年第3期1-13,共13页China Surface Engineering

基　　金：国家自然科学基金(52205578,52320105007);四川省区域创新合作项目(2022YFQ0113);中央高校基本科研业务费专项(2682024CG007)。

摘　　要：激光熔覆技术可用于钢轨局部损伤表面的局部修复,但局部修复钢轨材料的磨损与滚动接触疲劳损伤规律尚不清楚。通过在钢轨试样表面切除凹槽来模拟局部损伤,在凹槽处激光熔覆Ni基、Fe基和Co基自熔性合金粉末,分析修复钢轨微观组织与硬度,然后利用双轮对滚试验研究局部修复钢轨试样的磨损与滚动接触疲劳行为。结果表明,激光熔覆涂层形成了共晶与枝晶组织,Ni基涂层组织粗大、硬度较小,Fe基与Co基涂层组织尺寸较小,Fe基涂层硬度最大,Co基涂层硬度居中。相比未熔覆区域,激光熔覆区(涂层)塑性变形层厚度较小,且涂层原始硬度越高,硬化后硬度越大,但硬化率和硬化层厚度更小。未熔覆区滚动接触疲劳裂纹较长,但裂纹角度较小;熔覆区裂纹长度均有所降低,但裂纹扩展角度明显增大;熔覆区与未熔覆区结合处疲劳损伤最为严重,疲劳裂纹角度和深度均比熔覆区和未熔覆区更大。对比分析发现,Stellite21(Co基)熔覆试样摩擦因数较低,熔覆区与未熔覆区磨损深度差较小,抗滚动接触疲劳性能较好,较为适合钢轨局部损伤的激光修复。研究结果可为激光熔覆技术在钢轨局部修复上的应用与优化提供理论与技术指导。With an increase in the axle load of trains,damage to the rails becomes more severe,decreasing their service life.Thus,local repair could be a solution for rail surface damage.Laser cladding is a relatively new additive manufacturing technology that can be used for local damage repair.However,wear and rolling contact fatigue(RCF)damage behaviors,particularly the damage at the boundary between the clad and unclad zones,have not been thoroughly explored.Thus,a pothole is cut off from the U75V rail sample(a roller sample)to simulate the local damage on the rail.Ni-,Fe-,and Co-based self-fluxing alloy powders(F103,Fe-Cr,Fe-58,Stellite 21,Stellite 22,and Stellite 23)are laser cladded at the pothole using a CO2 laser with a rectangular spot size of 7 mm×1 mm,a laser power of 1.9 kW,a scan speed of 200 mm/min,and a powder feed rate of 15 g/min.The microstructure and hardness of the locally repaired rail materials are analyzed.The wear and RCF behaviors of the laser-repaired rail samples are studied using the twin-disc rolling test with a maximum contact pressure of 1.1 GPa,a slip ratio of 0.75%,and a rotational speed of 500 r/min.The number of cycles for each rolling test is 105.The friction coefficient,wear rate,depth,plastic deformation,and damage morphology are analyzed.The results showed that the cladded sample could be divided into three regions in the depth direction on the cross section or in the rolling direction on the surface:the clad zone,heat-affected zone,and substrate.Fine eutectic and dendritic structures are formed in the laser cladding.The hardness is higher than that of the substrate.The microstructure of the Ni-based clad is coarse,and its hardness is low.The microstructural sizes of the Fe-and Co-based clads are small.The hardness of the Fe-based clads is high and that of the Co-based clads has an intermediate value.During the rolling test,the friction coefficient exhibits an increasing trend during the running-in period and then remains stable.The stable friction coefficient is approximately 0.4 an

关 键 词：激光熔覆 损伤钢轨 微观组织 磨损 滚动接触疲劳 

分 类 号：TH117[机械工程—机械设计及理论]