Study On Thermal-mechanical Coupling Behavior And Processing Property Of Laser Controlled Cable-type Welding Wire GMAW

With the rapid development of modern industry,more and more industries such as shipbuilding industry and marine engineering use precision components,which require high efficiency,low heat input and small welding deformation in welding.The cable welding wire has the advantages of high efficiency,high quality and low energy consumption.The laser action droplet can effectively promote the droplet transfer and reduce the welding current.On this basis,the laser control cable welding wire GMAW(Gas Metal Arc Welding)welding method is proposed to ensure that the cable welding wire achieves stable transition at low current and increases the deposition amount.In this thesis,a lasercontrolled cable wire GMAW welding platform was established.The droplet transfer behavior,thermo-mechanical coupling behavior,weld formation and welded joint performance of cable wire GMAW under laser control were studied,which provided a theoretical basis for promoting the application range of cable wire GMAW.In this thesis,the surface evaporation behavior of droplets under laser irradiation was studied.It was observed that the metal vapor flow appeared at the laser action position on the droplet surface,and the basic law of the evaporation behavior of the droplet surface irradiated by laser was analyzed.The droplet transfer characteristics of laser controlled wire GMAW were studied by comparing with wire GMAW.The effects of laser incident position,laser incident angle,laser power and welding current on droplet transfer behavior were studied.The results show that when the laser acts on the necking position,it effectively promotes the droplet transition and has little effect on the droplet transition morphology.With the increase of laser incident angle,the droplet transfer frequency increases and the radial displacement decreases.With the increase of laser power,the droplet transfer frequency increases,the droplet size decreases and the transition process is stable.With the increase of welding current,the influence of laser evaporation reaction force on droplet transfer is relatively reduced,and droplet transfer is mainly affected by electromagnetic force.In this thesis,the arc morphology and plasma behavior of laser controlled wire GMAW are studied.The results show that the high temperature and high density plasma produced by laser action changes the arc energy distribution.The thermal-mechanical coupling behavior of laser-promoted droplet transfer was studied.The heat input of the laser to the droplet was calculated and the heat input of the laser to the molten pool was effectively reduced by the thermocouple.Combined with the droplet force analysis,the calculated evaporation reaction order of magnitude can effectively promote the droplet transfer.Based on Fluent software,a numerical model of droplet transfer under laser control was established.The influence of laser power on droplet transfer was explored through the model.The change trend of droplet transfer frequency with laser power was accurately simulated,and the mechanism of laser affecting droplet transfer was further confirmed.In this thesis,the law of weld formation under different welding parameters is studied.The results show that with the increase of welding current,the weld width and penetration increase.With the increase of laser power,the deposition amount increases,and the melting width and depth are effectively improved.With the increase of laser incident angle,the weld formation is uniform and continuous,and the penetration depth increases.Through the comparative study on the process performance of laser controlled wire GMAW and wire GMAW butt joints,it is found that laser action can effectively reduce the actual welding current,reduce the welding heat input,refine the grain structure of welded joints,and improve the mechanical properties of welded joints.The electrochemical corrosion performance of the joint was studied.It was found that the self-corrosion potential of the joint under laser action was higher,the self-corrosion current density was lower,and the electrochemical corrosion resistance was the best.