Longitudinal Magnetic Field Of Metal Surfacing And Wear Resistance,

With the rapid development of industrial technology and continued increase of the mechanization and automatization,people pay more attentions to hazard of parts wearing, which shows a great economic significance by decrease grinding abrasion and increasing mechanical wearing.This dissertation reports on the effect of longitudinal magnetic field on plasma overlaying of Fe-based and Ni-based welding alloy.Electromagnetic field is applied to welding technology in recent years to improve the properties of surfacing deposit. Electromagnetism is applied to welding as a new welding technology in recent years. People are very interested in electromagnetism because of its low cost and simple equipment.It is showed in experience that longitudinal magnetic field can give an effective intervention to the shape of arc,flowing of molten bath metal,crystalline and nucleation of molten bath and the process of crystalline growth in welding process.The texture of welding seam is refined,the degree of segregation is reduced,the gas cavity and hot crack is decreased,the quality of welding is increased.The influences of the applied surfacing current and magnetic current on hardness,wearing,microstructures and composition of the surfacing deposit have been compared with those obtained without magnetic field during the welding.The main results of this paper go as follow:(1)The surfacing deposit obtained by introducing magnetic field has better properties than that deposited without magnetic field;(2) The tests of hardness,wearing and microstructures show that the magnetic field can refine the primary structure and the secondary structure.The magnetic stirring can influence the nucleation ratio and refine the structure effectively;(3) The magnetic current and weld criterion parameters must be matched properly,then the optimal effect of grain refining can be gained.We have a systematic study on it.