Numerical Simulation Of Arc And Weld Pool Temperature Field In Plasma-MIG/MAG Hybrid Welding

Plasma-metal inert/active gas(MIG/MAG)hybrid welding is a new type of welding process that combines the two standard welding techniques,plasma welding and MIG/MAG welding technology.Due to the plasma arc and MIG/MAG arc are not isolated from each other during the hybrid welding process,they have mutual cooperation of electromagnetic environment,conducting air and establish the coupling process.So we can produce a lot of new advantages,such as relatively concentrated energy,higher filler metal deposition efficiency,stable,fine welding grain size,no spatter and fewer porosity,higher joint quality and the increased welding efficiency and so on.In this way,the hybrid welding heat source has a very complicated distribution and coupling mechanism.It is very difficult to analyze its characteristics in the present.With the rapid development of numerical analysis method which provides a new opportunity to study plasma-MIG/MAG hybrid arc.Fluent is used as a numerical analysis software.By using the equations of fluid dynamics,the theory of magnetic fluid dynamics(CFD)and Maxwell's equations,the two-dimensional and three-dimensional plasma-MIG/MAG hybrid welding arc mathematical models was established.The hybrid arcs and welding molten pool temperature field was simulated.First of all,according to the three conservation equations followed by fluid dynamics(mass conservation,momentum conservation and energy conservation)and Maxwell equations,a two-dimensional mathematical model of the hybrid arc was established.Then HyperMesh software was used to mesh.Hybrid arc region is very sensitive to temperature changes,so in this important region a fine mesh was generated to ensure a better accuracy.By determining the appropriate boundary conditions and coupling control equations,the SIMPLEC algorithm is chosen to solve the arc temperature field and flow field etc..By changing the plasma current,MIG/MAG current,two electrode spacing and plasma gas flow rate,the hybrid arc shape and temperature were observed to analyze their effects on the arc.Secondly,the plasma-MIG/MAG hybrid arc-molten pool uniform three-dimensional mathematical model was established.The model can avoid the hypothesis interface conditions between the hybrid arc and welding molten pool,so that the analysis of the hybrid arc and welding pool behaviors are more appropriate in the engineering practice.When the temperature field,the size of the weld depth and the width of the weld pool are obtained and compared with the data obtained from the experiment under the same welding process,the accuracy of the arc simulation is verified.In this paper,through the analysis and calculation of plasma-MIG/MAG hybrid welding arc and weld pool,it is beneficial to a deeper understanding of plasma hybrid mechanisms.It also provides a theoretical basis and guidance for the selection of hybrid welding parameters,and the metallurgical analysis.