Numerical Analysis Of Arc Characteristic Of T-joints By Laser+GMAW Hybrid Welding

Laser+GMAW hybrid welding technology that is one of the ideal choice to realize high quality and high efficiency welding of complicated structures,combines the advantages of both arc welding and laser welding,which has some characteristics of high welding speed,deep penetration,high stability,low deformation and low defect rate.There is a strong interaction between laser and arc in the process of hybrid welding technology.The synergistic effect has a significant impact on the stability of high-speed hybrid welding technology and the thermodynamic behavior of molten pool.However,the current researches involving the coupling mechanism between arc and laser are qualitative or semi-quantitative experimental studies by using the means of high-speed camera or spectral analysis,which concentrate mainly on the simple joints,such as flat welding,and few of them involve complicated joints.Therefore,in this paper,the arc characteristics of fillet joint are studied by combining numerical simulation with experimental detection during laser+GMAW hybrid welding technology,and the arc behavior is compared with that of the single GMAW welding.It has important academic significance and engineering value to give deep insight into the physical characteristics of complex joint in hybrid welding deeply and provide theoretical support and data foundation for optimization.In this paper,the single GMAW welding and laser+GMAW hybrid welding technology have been carried out under different conditions,and the dynamic behaviors of arc are detected by high-speed camera technology.Based on the mechanism of heat transfer,fluid dynamics and electromagnetism,the 3D asymmetric numerical model of arc in GMAW welding and laser +GMAW welding technology is built.The dynamic behaviors of arc in GMAW welding and hybrid welding are simulated under different conditions in FLUENT,and the simulated results are compared with the experimental results to verify the accuracy and applicability of the model.For single GMAW welding,the temperature field,velocity field,pressure field and potential field are studied under the conditions of different polarities,different welding current and different joint angles.The results indicate that there is a higher current density on the wiretip by using the DCRP,which leads to the maximum values of temperature,velocity and pressure.So there is a greater arc pressure on the workpiece surface.However,there is a larger potential gradient on the workpiece because of the higher saltation in the DCSP.With the current goes up,the peak value of temperature,velocity,pressure,potential,and all of these increase on the workpiece surface,but the deviation angle of wire decreases.With the joint angle increasing,the peak value of temperature,velocity,pressure,potential,and all of these increase slowly on the workpiece surface,but the pressure of workpiece surface decrease slowly.For the hybrid welding technology,compared with GMAW welding,because of the addition of metal vapor,the arc root was severely compressed,and the peak temperature of the arc decreased from 20482 K to 19828 K,the peak velocity decreased from 330m/s to 277m/s,and the peak pressure decreased from 1133 Pa to 760 Pa.The temperature,pressure and current density of the metal vapor area are higher than that of the single GMAW on the workpiece.As the laser power increases,it is found that the peak value of temperature,velocity and pressure on the wiretip are not significantly different,and the collision height of the arc plasma and metal vapor increases.The temperature,pressure and current density of the workpiece surface are bimodal,and the abrupt value of the metal vapor region increases as the increase of the laser power.With the increase of laser-arc distance,the radius of arc distribution and the peak value of temperature and pressure gradually increases,but the peak value of velocity slowly decreases.The effective distribution radius of temperature,pressure and current density on the workpiece surface also increases.Finally,the high-speed camera technology is used to capture the arc profile of laser+GMAW hybrid welding technology to verify the numerical model,which shows the simulation and experiment are in good agreement.However,it is found that the coupling effect between metal vapor and arc plasma is not ideal,so the metal vapor model needs to be further optimized.