Effects of Active Fluxes in Gas Metal Arc Welding

In this paper the effects of active fluxes during gas metal arc welding (GMAW) were investigated. Eight different types of active fluxes, with different oxygen content, and MnO – SiO2 flux mixtures were applied to the surface in 20 vol.% steps before welding. The used shielding gas was 82 % Ar + 18 % CO2 (ISO 14175 M21) in all cases. Even small amount of active flux altered the weld face geometry, according to the cross sectional stereo micrographic images. The most significant effect on the internal form factor was experienced in case of MnO active flux, which decreased the internal form factor by 20 %. In case of the external form factor the applied SiO2 active flux caused the biggest increase which is 37 %. In the hardness distribution and the microstructure of the joints, including the weld metal and the heath affected zone, no significant differences were experienced compared to the sample welded without any flux material