Numerical Simulation Study On The Of External Transvers Mangnetic Field On The Characteristics Of TIG Welding Pool With Aluminum Alloy Wire Filling

6061 aluminum alloy is mainly composed of Al,Mg,Si and other elements.Because of its excellent corrosion resistance,good oxidation resistance and high specific strength,it is widely used in automobile parts,building decoration,medical machinery and intelligent electronics and other industries.At the same time,due to the series of metal weldability,high toughness,easy processing and processing is not easy to deformation and other characteristics,in the field of aerospace fixed devices,communications,electrical device fixing and other applications,its typical uses include mold manufacturing,precision machining workpiece,mechanical parts and precision instruments.The characteristics of Tungsten Inert Gas welding pool of 6061 aluminum alloy before and after applied transverse magnetic field are studied in this paper.Firstly,the numerical model of TIG welding pool of 6061 aluminum alloy was established by ICEM,and the characteristics of TIG welding pool before and after magnetic field was applied were simulated and studied,and the characteristics of welding pool under different process parameters were compared.And then,the influence and mechanism of external magnetic field on aluminum alloy TIG welding pool were analyzed by welding test.When the transverse magnetic field was not applied,the molten pool was not completely formed at the beginning of welding,and the temperature of the molten drop reached 1311.82 K in the falling process,and dropped to 1038.58 K after entering the molten pool.When the droplet began to fall,the maximum velocity was 1.379 m/s,and when it was about to enter the molten pool,it reached 1.583 m/s.After entering the molten pool,the velocity gradually decreased to a relatively stable size.On the one hand,the droplet impact on the molten pool makes the maximum velocity of the molten pool reach 1.044 m/s,on the other hand,it also changes the temperature distribution of the molten pool.Directly below the molten drop,due to the impact of the molten drop,more liquid metal with higher temperature begins to flow to the bottom of the molten pool,thus driving the temperature transfer downward,prompting more heat into the bottom of the molten pool,and finally increasing the depth of the molten pool.The liquid metal inside the molten pool extends backward under the action of various forces,and the volume of the high temperature area expands.After applying transverse magnetic field of different intensity,the maximum temperature in the molten pool began to decrease with the increase of magnetic field intensity.When the external magnetic field intensity increased from 0.1 m T to 0.2 m T,the temperature in the molten pool decreased from1588.24 K to 1501.63 K.The high temperature zone in the molten pool expands outward obviously,and the temperature at the edge of the molten pool increases.The applied magnetic field improves the fluidity of liquid metal in the molten pool and reduces the impact of droplets on the molten pool.At the same time,the external magnetic field improves the fluidity of liquid metal in the molten pool and reduces the impact of droplets on the molten pool.The maximum velocity in the molten pool also begins to decline.When the external magnetic field intensity increases from 0.1 m T to 0.2 m T,the maximum velocity in the molten pool decreases from 0.956 m/s to 0.945 m/s.The external magnetic field and the electromagnetic force generated by welding current produce an electromagnetic stirring to the molten pool,which makes the heat in the center of the molten pool transfer more to the edge of the molten pool with the improved liquidity of the liquid metal,thus reducing the temperature gradient of the molten pool.Meanwhile,the liquid metal in the edge area also obtains better liquidity and the melting width becomes longer.The external magnetic field reduces the impact of the droplet on the center of the molten pool.With the increase of magnetic field intensity,the influence of droplet fall on the molten pool increases,and the influence on the bottom of the molten pool becomes smaller,while the penetration becomes smaller.The same process parameters as the simulation were used to demonstrate the TIG welding of 6061 aluminum alloy,the results show that the weld width of the molten pool widens with the increase of the magnetic field intensity,while the residual height and depth of the molten pool decrease,the grain size on the cross section of weld decreases with the increase of applied magnetic field intensity.When there is no external magnetic field,the dendrites produced near the fusion line are coarse and large in size,as the intensity of the applied magnetic field increases,the dendrites here gradually become thinner and more abundant.With the increase of magnetic field intensity,on the one hand,the grain refinement effect at the center of the molten pool is more obvious,and the number of grains increases greatly when the area is the same.On the other hand,the number of pores in the weld decreases obviously,and the diameter of pores decreases with the increase of magnetic field intensity,and the position of porosity defect moves to the surface.