Numerical Simulation Of Heat And Mass Transfer Of Arc And Pool In Arc Additive Manufacturing

Arc increasing material manufacturing technology is based on the traditional welding technology,the main physical and chemical process is very complex,including plasma arc combustion,melting drop transition,molten pool flow and solidification and complex thermal cycle and stress and strain,etc.These macroscopic phenomena will eventually affect the evolution process and grain morphology of microstructure,thus affecting the mechanical properties of forming parts.In order to achieve the structure "control" and "control" parallel manufacturing goal must be to explore the internal mechanism of the arc and molten pool of metal transport,this article emphatically through many physical field coupling numerical calculation method to explain the heat mass transfer process.In this paper,a 3d model of GTAW arc is established by reasonable assumption,and the model is imported into Fluent software for solving.Welding current 200 A,welding voltage 19 V,wire radius 1.6mm,wire feeding speed 1.8m/min,welding speed 200mm/min,high purity argon gas protection(15.5l /min).The results show that the arc temperature above 18000 k,900 pa maximum pressure arc,arc plasma velocity of 220 m/s,maximum potential difference is 9 v(if considering the role of the sheath layer pressure drop,after correction for about 20 v,and electromagnetic force in the plasma equilibrium in the X,Y offset each other on the positive and negative direction).The arc shape of the high-speed camera is similar to that of the simulated arc,and the distribution law and numerical value of the arc temperature field measured by the spectroscopic method are the same as that of the simulated temperature.In the molten pool metal transport model,the physical model is established with the same coordinate system as the arc model,and the welding gun is fixed and the metal flow.By simplifying the model,the droplet is regarded as a ball,and the quality source of the molten pool is injected at a fixed frequency,thereby achieving the mass transport.Should be fully considered in the model a variety of factors,including the electromagnetic force,buoyancy,arc pressure,etc.,also consider arc heat transfer,the high temperature of molten drop and the metal solidification process of phase change latent heat,which mainly through the action of UDS arc interpolation and CSF method is loaded into the molten pool in the model.Finally combining independent programming,loading the integrated thermal boundary conditions of the gas liquid two phase interaction,bead surface morphology is obtained under drop impact and and molten pool temperature field distribution of weld bead(maximum is 2200 k).At last,the temperature distribution of the welding channel is taken by infrared camera,and the numerical value is the same as the simulation result.Based on the actual model,using the means of numerical calculation,the arc model and the nature of heat mass transfer in metal transport model to solve the analysis,reveals the physical field coupling results,and from thermodynamics,fluid mechanics,electromagnetism and so on many aspects has carried on the mechanism research,for the future of process optimization and parts of shape control sex research laid the foundation.