液压千斤顶活塞杆用激光熔覆研究进展

综述了液压千斤顶活塞杆激光熔覆的研究进展,包括材料体系、耐蚀性能、耐磨性能、硬度、疲劳性能以及熔覆效率等方面。探讨了活塞杆常用熔覆层耐蚀性能的评价方法、性能参数及影响因素。各种试验结果表明,熔覆层的稀释和表面缺陷对耐蚀性能有不利影响,应通过工艺过程控制,同时完善检测手段;分析了液压千斤顶活塞杆的磨损机理及评价方法,重点探讨了常用材料在三体磨粒磨损与二体磨粒磨损工况下的耐磨性能,发现三体磨粒磨损和二体磨粒磨损对材料的硬度要求不同;考虑到第二相硬化导致耐蚀性能的降低,不应刻意通过第二相强化手段提高材料硬度而保证耐磨性能,应通过结构设计和维护保养避免磨粒磨损,在此前提下,保证熔覆层硬度在450HV左右是合适的。激光熔覆导致材料疲劳寿命的降低,主要原因在于残余拉应力和表面缺陷。鉴于加工硬化对熔覆层硬度和应力状态的影响,应进一步加强在疲劳寿命方面的研究,以进一步加快应用。为提高熔覆效率,在保证低稀释率的前提下,通过降低熔覆层的厚度,进而提高熔覆效率的方法是一种新的研究方向。

Laser Cladding for Piston Rods of Hydraulic Jacks

The research progress of laser cladding for piston rods of hydraulic jacks, including material system, corrosion resistance, wear resistance, hardness, fatigue property and cladding efficiency, was reviewed. Evaluation methods, performance parameters and influencing factors of corrosion resistance of common cladding layer on piston rods were discussed. Various tests indicated that dilution and surface defect of cladding layer had adverse effect on corrosion resistance. Surface defects should be controlled through cladding processing and detection means should be improved. Wear mechanism and evaluations methods were analyzed, and the emphasis was laid on the wear resistance of common cladding layer under three-body and two-body abrasive wear, respectively. It was found that requirements for coating hardness were different under different wear condition; the coating hardness should not be increased deliberately to guarantee wear resistance in second phase strengthening method since second phase hardening might reduce corrosion resistance. Abrasive wear should be prevented through structural design and maintenance. Under this premise, proper coating hardness should be 450HV. Fatigue life reduction after laser cladding was caused by residual tension stress and surface defect. Due to beneficial effects of work-hardening on stress status and coating hardness, study on fatigue life should be enhanced to accelerate application. It was a new research orientation to improve cladding efficiency by reducing thickness of cladding layer at low dilution rate.