The Study On Microstructure And Properities Of Fe-Based Surfacing Layers With Introducing DC Transverse Magnetic Field

Following the rapid development of industry technology and continued increase of the degree of mechanization and automation,more attentions have been taken on hazard of parts wearing. It has a great economic significance that decrease grinding abrasion and increase mechanical wearing. Electromagnetic has been used to welding process as a new welding technology in recent years. The magnetic field promotes arc revolution,changes plasma jet of arc column and radial distribution of density of arc,affects the heating and melting of base metal and formation of welded joint. Experience shows that the introduced magnetic field can give a 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,improves quality of surfacing deposit.The Fe5,Fe90 was surfaced on low carbon steel using plasmatron under transverse magnetic field. The effect of surfacing current and magnetic field current on hardness,wearing,microstructure of surfacing deposit was researched by hardness test,wearing test and SEM,and the action mechanism of introduced magnetic field on surfacing deposit was discovered. The main results as following:1.Magnetic field refines the grain of surfacing deposit,the properties of surfacing deposit with introduced magnetic field are better than he properties of surfacing deposit without magnetic field. The optimal value is obtained when the surfacing current and magnetic field current match well.2.For Fe5 alloy,the optimal value of surfacing layer is face hardness HRC74.3,side hardness HRC76.3,wearing capacity 0.0183g when I=180A,magnetic field current is 3A.3. For Fe90 alloy,the optimal value of surfacing layer is face hardness HRC70.8,side hardness HRC71.3,wearing capacity 0.4218g when I=180A,magnetic field current is 3A.4.The mass transfer and heat transfer of surfacing are changed by magnetic field,and the crystalline,nucleation of molten bath and distribution of hardness phases are improved. The hardness phases exhibit regularity distribution under appropriate parameters. The microstructures of surfacing layer are improved and the properties of surfacing layer are increased. But properties of surfacing layer decreased when magnetic field current is too big,the electromagnetic damping acts mainly at this time.