感应重熔对高速轧机轴承热喷涂层微观组织性能的影响

Effect of induction remelting on microstructure and properties of hot spraying coating for high speed rolling mill bearings

为了改善高速轧机轴承热喷涂层的微观组织性能,采用感应重熔技术对GCr15轴承钢表面预制备的高能火焰喷涂Ni60A涂层进行感应重熔处理,并利用金相显微镜、扫描电镜、X射线衍射仪、显微硬度计对感应重熔前后涂层的孔隙率、微观组织、显微硬度等进行对比研究,探讨感应重熔对涂层以及界面微观组织、显微硬度的影响。结果表明,高能火焰喷涂镍基涂层的孔隙率高达5.09%,且表面孔洞缺陷较多,涂层与基体结合的界面处存在较明显的界面裂纹和孔隙缺陷,呈现典型的机械结合,界面结合特性较差;而经感应重熔后其涂层组织致密,孔隙率仅为0.27%,涂层缺陷明显减少,与基体结合的界面处呈现出强冶金融合特性,且涂层中硬质相数量显著增多,涂层及界面的显微硬度均得到较大提升。因此,感应重熔技术可改善涂层的表面组织性能,在高速轧机轴承表面强化方面有一定的应用价值。

In order to improve the microstructure and properties of hot spraying coating for bearing of high speed rolling mill,induction remelting was carried out on the Ni60A coating which was prepared on the surface of GCr15 Bearing Steel by high energy flame spraying.The porosity,microstructure and microhardness of the coating before and after induction remelting were analyzed comparatively by metallographic microscope,scanning electron microscope,X-ray diffractometer and microhardness tester.The effect of induction remelting on the microstructure and microhardness of the coating and interface was investigated.The results show that the porosity of nickel based coating prepared by high energy flame spraying is as high as 5.09%,and there are many surface pore defects,as well as there are obvious interface cracks and pore defects at the interface between the coating and the substrate,showing typical mechanical bonding and poor interface bonding properties.However,after the induction remelting,the microstructure of the coating is dense,the porosity is only 0.27%,the defects of the coating are obviously reduced,and the bonding interface between the coating and the substrate shows strong metallurgical fusion characteristics.Additionally,the amount of hard phase in the coating increases significantly,and the microhardness of the coating and interface is greatly improved.Therefore,the induction remelting process can not only improve the surface quality of hot spraying coating for high-speed rolling mill bearings,but also improve the interface bonding characteristics of the coating.The application of induction remelting technology can improve the coating surface structure property,and it may be used in the surface strenthening of high-speed rolling mill bearings for some point.