(华中科技大学 材料成形与模具技术国家重点实验室，武汉 430074)
摘 要: 为了提高高品质液压油缸的耐磨性能，使用45钢作为模拟材料，采用YLR-4000型光纤激光器在其表面进行激光熔覆，制备NiCrMn+WC复合涂层。利用金相显微镜(OM)和扫描电镜(SEM)分析其显微组织和微观形貌，利用X线衍射仪及能谱分析涂层的相结构和成分，并测量了其硬度以及磨损性能，获得最优的工艺参数。结果表明：激光熔覆层的致密度良好，无明显的孔洞出现；熔覆层硬度较基体的提高3~5倍，且在一定范围内，随着扫描速度的增加以及扫描功率的减少，熔覆层的硬度强化效果明显；硬质相的加入使其表面的耐磨性显著提高，在扫描速度为360 mm/min，功率为2.5 kW，WC含量为30%(质量分数)时，熔覆层的各项性能达到最优。
关键字: 液压油缸；激光熔覆；能量密度；硬度；耐磨性
（Key Laboratory of Material Processing and Die and Mould Technology,
Huazhong University of Science and Technology, Wuhan 430074, China）
Abstract:In order to improve the wear resistance of high-quality hydraulic cylinder, 45 steels were used as the simulative materials, the surface layers NiCrMn-WC composite coatings were fabricated by laser cladding. The microstructure and morphology were analyzed by optical microscopy (OM) and scanning electron microscopy (SEM), the phases and component elements were analyzed by X-ray diffractometry (XRD) and energy dispersive spectrometry (EDS), the microhardness and wear-resistance were tested, and the optimal parameters were obtained. The results show that the appropriate treatment parameters result in good performance of the clad layers with no defects, the microhardness of the CZ is 3-5 times larger than that of the substrate, and the microhardness is promoted as the power reducing and the scanning speed increasing, the wear-resistance is improved with the hard phases adding, each property comes to the best when the power is 2.5 kW, the scanning speed is 360 mm/min and the WC content is 30% (mass fraction).
Key words: hydraulic cylinder; laser cladding; energy density; microhardness; wear-resistance
