The Study On Negative Polarity Weak Plasma Arc Dissimilar Material Surfacinf Welding

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.On account of new material,new craft,new the equipments continuously appearance,the higher requirements are put forward to the performance of parts.The copper-steel compound parts are adopted,with the advantage complementation of each other on performance and economy,have vast of application foreground.Negative polarity plasma arc is used as electrode to melt Al-bronze alloy powder in the building-up welding experiment the surfacing processing parameter is continuous setting in the surfacing welding.The effect of surfacing processing parameter on overlay's mechanical properties is studied through analyzing the average degree of hardness,the frictional wear testing and the microstructure.The mechanism for plasma arc overlay formability,composition and fiction-wearing by overlay surfacing processing parameter has been discussion intentionally.The paper also makes theoretical analysis and preliminary discussion on the wear resisting mechanism of the overlay.Following are the main results:(1) Plasma arc surfacing layer penetration is increase along with the surfacing welding current increase,but have inverse relationship with powder-output and welding speed.The formability of Plasma arc surfacing layer is the best with the welding current is 85A, powder-output is 15/min and welding velocity is 80mm/min,when the other parameter is invariable.(2) Through the surfacing layer composition analysis,mechanism of surfacing layer combine with low-carbon steel is studied.Aluminum bronze plasma arc welding layer be composed ofαphase,γ₂ phase,β₁ phase and K phase. (3) The frictional wear's weight loss and length loss of plasma arc welding layer with metal grinding friction are become small first and then increase with the welding current increasing. The friction and wear between layer and metal is mainly abrasive wear and adhesive wear-oriented.