Journal of Hebei University of Science and Technology (Aug 2021)
Effect of induction remelting on microstructure and properties of hot spraying coating for high speed rolling mill bearings
Abstract
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 509%,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 027%,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.
Keywords
