The Analysis Of Spatter In MAG Welding Of Low-Carbon Steel

In this paper,the high-speed camera system was used to observe the droplet transfer and spatter of low-carbon steel in MAG welding.The types and characteristics of the droplet transfer under the experimental parameters of the low-carbon steel in MAG welding were summarized.The processes and causes of the spatter generation were described.It is significant to prevent the spatter.The welding processes were carried out with the welding current 250A and the voltage26.8V,and comparison of the effects of different shielding gases on droplet transfer.The results showed that when the shielding gas was 1%O₂+9%CO₂+90%Ar,the droplet transfer was streaming transfer,and it was not easy to produce spatter.When the shielding gas was 1%O₂+18%CO₂+81%Ar,the droplet transfer was short-circuiting transfer,and the spatter was large.With the shielding gas 5%O₂+10%CO₂+85%Ar,the droplet transfer was a mixed transfer of streaming transfer and short-circuiting transfer,and the spatter was larger.When the selected shielding gas was 5%O₂+1%CO₂+94%Ar,the droplet transfer presented streaming transfer and there was small spatter.With the shielding gas 1%O₂+9%CO₂+90%Ar,the droplet transfer changed from the short-circuiting transfer to streaming transfer when the welding current and the voltage changed from 126A/17.4V to 270A/18.6V gradually.The droplet transfer matched with current and voltage waveforms.The arc area was reduced when the shielding gas had the CO₂,which was not conducive to the droplet transfer,and the spatter was large.The streaming transfer occurred when the shielding gas had a high content Ar,and the spatter was reduced.With the shielding gas had a little O₂,the surface tension would be reduced,and also the spatter would be reduce.Based on the two-phase flow and fluid heat transfer module,COMSOL Multiphysics software was used to add the Arc Gaussian heat,gravity,surface tension and Arc source to the energy and momentum constitutive equations respectively.For different process parameters,the droplet transfer model was established.The results showed that with the increase of welding current,the droplet transition changed into globular transfer,projected transfer and streaming transfer gradually,and the simulation results were consistent with the experimental results.