The Influence of Oxygen Additions on Argon-Shielded Gas Metal Arc Welding Processes

It has been observed experi- mentally that small additions of oxygen to the argon shielding gas affect the gen- eral operation of GMAW processes. By theoretically modeling the arc column, it is shown that the addition of 2 to 5% oxy- gen to argon has an insignificant effect on the arc characteristics. This corresponds to the minor changes in the thermophys- ical transport and thermodynamic prop- erties caused by the oxygen addition. Therefore, it is concluded that the addi- tion of oxygen to the argon shielding gas mainly affects the anode and the cathode regions. From the literature, it was found that the formation of oxides initiates arc- ing at the cathode and decreases the movement of the cathode spots. These oxides can also improve the wetting conditions at the workpiece and the elec- trode. Finally, oxygen is found to affect the surface tension gradient and thereby the convective flow of liquid metal in the weld pool.