重熔温度对GCr15轴承钢表面感应重熔镍基涂层微观组织性能的影响

Effects of Remelting Temperature on Microstructure and Properties of Induction Remelting Ni Based Coating on GCr15 Bearing Steel

目的获得优化后的感应重熔工艺参数,改善GCr15轴承钢表面感应重熔镍基涂层的微观组织性能。方法采用高能火焰喷涂法在GCr15轴承钢基体上预制备Ni60A涂层,并且分别在960、1012、1052℃重熔温度下对预制备的涂层进行感应重熔,获得3种感应重熔镍基涂层,并通过金相显微镜、扫描电子显微镜、X射线衍射仪、显微硬度计对其孔隙率、微观组织、显微硬度等进行了对比研究,探讨了重熔温度对感应重熔涂层微观组织性能的影响,并揭示了涂层的形成机制及增强机理。结果与960、1052℃重熔温度制备的感应重熔涂层相比,1012℃时制备的重熔涂层更加致密,孔隙率仅为0.27%,缺陷数量明显减少,缺陷尺寸明显减小,硬质相数量显著增多,且Ni元素与Fe元素在界面混合交叉密布,形成了强冶金结合的融合区,有利于提高涂层与基体的界面结合强度。此外,该涂层的表面及界面融合区的平均显微硬度均高于其他两种涂层,且硬度极差较小。结论合理地控制重熔温度,能够有效改善感应重熔镍基涂层的微观组织性能,以及涂层与基体的界面结合特性,并提高涂层的显微硬度。

In order to obtain the optimized induction remelting process parameters and improve the microstructure and properties of nickel-based coating on GCr15 bearing steel surface.Ni60A coatings were prepared on GCr15 bearing steel substrate by high energy flame spraying,and then were remelted at 960℃,1012℃and 1052℃ respectively to obtain three kinds of induction remelting nickel-based coatings.The porosity,microstructure and microhardness of the three kinds of coatings were measured and compared by metallographic microscope,scanning electron microscope,X-ray diffractometer and microhardness tester.The effect of remelting temperature on the microstructure and properties of the coating was discussed,and the formation mechanism and strengthening mechanism of the coating were revealed.Compared with the induction remelting coating prepared at 960℃ and 1052℃,the remelting coating prepared at 1012℃ is more compact,with a porosity of only 0.27%.The number and size of defects are significantly reduced,and the number of hard phases is significantly increased.Moreover,Ni and Fe elements are mixed and cross-distributed at the interface,forming a strong metallurgical fusion zone,which is conducive to improving the interface bonding strength between the coating and the substrate.In addition,the average microhardness of the surface and interface fusion zone of the coating is higher than that of the other two coatings,and the hardness difference is small.Reasonable control of remelting temperature can effectively improve the microstructure and properties of Ni-based coating,the interface bonding characteristics between the coating and the substrate,and improve the microhardness of the coating.