The Research On Arc Plama And Formability Mechanism Of Welding Line During CO₂ Welding By Eerteral Magnetic Control

This paper tries to solve two major defects of CO₂ welding by the method of magnetic control. The defects, which is always restricts the development of CO₂ welding, are the high spatter rate and the poor performance of welding line. The behavior of arc, metal droplets transition and the performance of welding line formability were respectively measured after the additional longitudinal electromagnetic field were Introduced into the CO₂ welding. The mechanism, which is the decrease of spatter rate and the optimization of welding line formability, are revealed from the respect of arc shape and force made on the droplets. And it also provides some reference value for the application of magnetic control technology in welding.First, to observe the shape of welding arc by the technology of high speed camera in different intensity and frequency of magnetic field, and also establish the mechanical model of the welding arc in order to reveal the principle of arc shape change. Then the spatter rate,time and frequency of droplet transition during the arc burning and short circuit phase were measured and also establish the mechanical model of the droplets to reveal the principle of time decrease and frequency increase of droplets transition. At last, the change of width and depth of welding line and the optimization of welding line formability were studied in the condition of longitudinal electromagnetic field.The results show that the shape of welding arc changed from the shape of cone to bell and also rotating according to a certain direction in the magnetic field parameters of 1A50 Hz,which increases the stiffness and stability of the welding arc. The arc becomes unstable and radius reduced when the tintensity of magnetic field was continue to increase. The method of magnetic control can effectively shorten the time and increase the frequency of droplet transition, reducing the phenomenon of welding splash during the arc burning and short circuit phase in the magnetic field parameters of 1A50 Hz, but the effect of the magnetic control will become worse when the magnetic field parameters increased. At last, the additional magnetic field can increase the weld fusion width and penetration and also have some good effect of stir and scour on the droplets, which can promote the nucleation of crystal, refinement grain, homogeneous microstructure and reduce formation of limb crystal.It can improve the mechanical properties of welding line and welding quality on the macro performance.