铁路货车轮辐板孔裂纹激光再制造

Remanufacturing Railway Wheels with Web Plate Hole by Laser Cladding Cracks

铁路货车轮在辐板孔处产生疲劳裂纹,影响安全运行。文中利用激光熔覆技术,采用镍基合金在车轮辐板辗钢CL60试样表面进行激光再制造试验研究,评价激光再制造试件的组织和性能。结果表明,熔覆层无裂纹、夹杂和气孔等缺陷,与基体形成了良好冶金结合,熔覆层组织是铸态的奥氏体组织,主要由弥散的共晶和亚共晶组成。激光再制造试件力学性能优于车轮基体材料,延伸率提高90%,冲击韧性提高2～3倍,熔覆层的显微硬度提高近50%,疲劳强度提高2.2倍。该工艺用于生产实践,经十万公里试运行考核验证,激光再制造后的车轮满足铁路货运的要求。

The Railway wheel generated fatigue cracks at the wheel web plate holes,which would arouse safe servicing problem.In order to remanufacture the wheels with web plate hole cracks,laser cladding technique was employed to fabricate nickel–based alloy coatings on steel CL60 from which the railway wheels were made.Microstructure and properties of the laser clad samples were analysed.The results showed that the cladding layer was free of cracks,inclusions,pores and other defects,and metallurgically bonded with the substrate material.The clad microstructure was cast austenite,mainly composed of eutectic and hypoeutectic phases.Mechanical performance of the laser clad samples was better than the wheel steel CL60.Its elongation was 90 % higher than the wheel base,impact toughness increased by 2 to 3 times,microhardness of clad increased by about 50 %,fatigue strength increased by 2.2 times.The process has applied to production practices,test running by the hundred thousand kilometers verificated the laser remanufactured wheels could meet requirements of rail freight.