| Red copper is widely used for its physical and chemical properties, such as excellentcorrosion resistance and antifriction. The valve which is the most commonly used inindustrial components has been widely applied. But sealing faces of valves are easy to becorroded and abraded in the process of its repeat switch，which were vulnerable to bedamaged and affect its service life. So it has important theory meaning and practice valueto research the resistant material which would prolong the lifetime of valves and increasethe economic performance.Red copper is welding on the surface of20G and HT200with plasma arc undertransverse direction magnetic field. The comparison analysis of the formability, hardness,wearing resistance, erosion resistance, microstructure under different welding current andmagnetic field currentwas investigated by experimental method. And interfacing bondingmechanism of surfacing layer are tested and studied. The influence rule and actingmechanism of magnetic field currents and welding currents on properties andmicrostructure of surfacing layer are researched. The main results are as following:（1）For red copper and low-carbon steel surfacing layer without external magneticfield, the formability of surfacing layer, mechanical properties has reached the bestcondition when the welding speed is120mm/min, powder feed rate is15g/min, weldingcurrent is120A.The hardness is58.05HV, wear extent is0.0118g, friction factor is0.70.At this time the microstructure of surfacing layer consists of small equiaxed grain. Thecorrosion resistance is worst when the welding current is100A and the corrosion potentialof the surfacing layer is-0.2778mv; The corrosion resistance is best when welding currentincreases to140A, and the corrosion potential surfacing layer has reached the maximum of-0.1274mv.（2）For red copper and cast iron surfacing layer without external magnetic field, theformability of surfacing layer, mechanical properties has reached the best conditionwhenpowder feed rate equal to15g/min,welding speedequal to120mm/min, weldingcurrent equal to120A.At the moment, hardness is82.06HV, wear extent is minimum valueof0.0147g, fraction factor is0.73.The erosion resistance of surfacing layer is not goodwhen the welding current equal to100A,the corrosion potential equal to-0.3250mv. Theerosion resistance of surfacing layer is well when welding current increase to140A, thecorrosion potential reach to a maximum value of-0.1762mv. （3）For red copper and low-carbon steel surfacing layer which magnetic field actedon it, the formability of surfacing layer, mechanical properties and microstructure hasreached the best condition when welding current equal to120A,magnetic field current equalto2A.At this time, hardness is50.16HV, wear extent is0.0027g, fraction factor is0.6, themicrostructure of surfacing layer consists ofrelatively smallequiaxedgrain. For red copperand cast iron surfacing layer, the formability of surfacing layer, mechanical properties andmicrostructure has reached the best condition when welding current equalto130A,magnetic field current equal to2A.At this time, hardness is69.47HV, wear extentis0.0015g, fraction factor is0.5, the microstructure of surfacing layer consists of relativelysmall equiaxedgrain. Regardless of the current for120A or130A, the erosion resistanceof surfacing layer is best when magnetic field current is2.5A, the corrosion potential is-0.126V and-0.102V.（4）Following the law of solute redistribution, Cu-Fe binary metallic is submitted todiffuse. Under the small growth rate,solutes atoms can be fully spread, and dissolved theCu intoFe,make it close to the segregation coefficient in equilibrium state. Under the largegrowth rate, diffusion of the interface solute is restrained, whichcan lead to soluteenrichment within the solid state, and the solute segregation coefficient is larger thantheequilibriumstate.（5）Induced by the extra magnetic field, plasma arc andliquid molten poolrotarymotion occurred which can formed electromagnetic stirring.Electromagnetic stirring hasthe positive effects on theelectric arc. It can act on molten pool, change surfacing layergrain nucleation and growth process. With the increasing of the magnetic field current,magnetic induction intensity will also raise. This causedmagnetic diffusion of surfacinglayer liquid molten poolincrease, the element migration and diffusion. It can also makesurfacing layer uniform and aesthetic, which can be appropriately to improve thecomprehensive mechanics performance of the surfacing layer. |
PDF Full Text Request