激光熔覆高硬涂层裂纹控制研究

Research on Controlling the Crack in Laser Cladding of High Hardness Coating

为了解决激光熔覆高硬涂层开裂的问题，采用CO2激光在20CrMnTi钢表面进行了激光熔覆Colmonoy88合金涂层（熔覆层维氏硬度超过了800HV0．1）的研究。采用扫描电镜和能谱分析仪对熔覆层微观组织结构进行了分析，并采用显微硬度计、摩擦磨损试验机等仪器对其性能进行了测试。研究发现提高预热温度可以显著降低熔覆层的开裂倾向，但不足以使熔覆层中裂纹完全消失；而CeO2的掺入也可以减少熔覆层中裂纹数量，且当CeO2的含量w（CeO2）≥0．10％时，熔覆层中裂纹完全消失。试验结果表明，CeO2的掺入能使熔覆层中晶粒得到细化，显微硬度分布变得均匀，耐磨性能得到提高；且当CeO2的添加量为w（CeO2）=0．10％～0．15％时，熔覆层耐磨性能获得最大提高，与未添加CeO2时相比提高了约67％，磨损形式为磨粒磨损。

In order to solve the cracking of high hardness laser cladding coating, which micro-hardness was more than 800 HV 0. 1, the technology of laser cladding Colmonoy88 alloy coating on 20CrMnTi steel by COz laser was investigated. The microstruc- ture, micro-hardness, the friction and wear characteristics were systematically studied by means of SEM, EPMA, micro-hard- ness tester as well as friction and wear tester. It was found that both increasing the preheating temperature and doping the CeO2 can significantly reduce the cracking of the cladding layer, but it was not enough to make the cladding layer cracks disap- pearing entirely by the preheating temperature. When the preheating temperature was 500℃ and the CeO2 contents wasn＇t less than 0.10 wt%, the cladding layer cracks disappeared entirely. The experimental results showed that doping CeO2 can make grains refined in the cladding layer and micro-hardness distribution become uniform and wear-resisting performance improved. Compared with no doping CeO2, the wear-resisting performance of cladding layer increased farthest, and improved about 67% when the CeO2 content was 0.10 wt%0.15 wt%. The wear form was abrasive wear.