The Study On Wear Resistant Mechanism Of Co-based And Ni-based Surfacing Alloys With Introducing DC Transverse Magnetic Field

With the rapid development of industry technology and continuous increase of the degree of mechanization and automation,people pay more attention to hazard of parts wearing. In all the abrasion types, the grinding abrasion takes the greatest percent. It has a great economic significance to decrease grinding abrasion and increase mechanical wearing. At the present time, some surface peening technology can be used to improve the ability of wear resistance. Thus, more and more attentions has been paid to the problem that how to ulteriorly improve wear resistance of materials on the basis of current technology.Electromagnetic is applied to welding as a new welding technology in recent years. The introduced magnetic field can give an effective intervention to the transition of droplet, flowing of molten bath metal, crystalline and nucleation of molten bath and the process of crystalline growth. The magnetic field promotes the refining degree of primary crystallization structure, decreases the chemistry non-homogeneity. So it can strengthen hardness and wear resistance of surfacing layer and improve quality of the surfacing layer.In this project, for the purpose of improving the properties of surfacing layers, studying the influence of surfacing current and magnetic field current on hardness and wear resistance of surfacing layer, a DC transverse magnetic field was applied during plasma arc surfacing Co-based alloy and Ni-based alloy on low-carbon steel. The hardness, wear resistance, microstructure and phase constitution of the surfacing layers were investigated via hardness and wear tests as well as SEM, EDS and XRD analysis. The influence of DC transverse magnetic field on the microstructures and wear resistance was systematically studied. Furthermore, preliminary analysis and discussions of the DC transverse magnetic field mechanism were made. Following are the main results:1. Introducing a DC transverse magnetic field during plasma arc surfacing, the hardness and wear resistance of the surfacing layer can be significantly improved .In the appropriate magnetic field parameters, the surfacing current and magnetic field current must be matched properly to achieve the optimal properties of surfacing layer.2. The plasma arc surfacing layers with introducing DC transverse magnetic field has better wear resistance than that without introducing magnetic field.3. When the surfacing current is 160A and the magnetic field current is 3A, the optimal effect of grain refining can be gained, the optimal hardness and wear resistance can be obtained for the Co-based plasma surfacing layer, where the hardness is HRC56 and the wear loss is 0.4442g; When the surfacing current is 140A and the magnetic field current is 2A, the hardness and the wear loss of Ni-based surfacing layer are HRC66.3 and 0.0767g, separately. At the point, the amount of hard phase is the most and the distribution of hard phase is even.