Fume Generation in CO₂ Arc Welding by Flux-cored Wire

Abstract

The effects of welding parameters and wire compositions on the fume emission rate of CO₂ arc welding by flux-cored wire, have been studied. In addition, high-speed photographs of the welding arcs have been observed in relation to an investigation of fume generation mechanism.
As the welding current and arc voltage are raised the fume emission rate increases, while it drops as tip-plate distance is increased. Addition of argon gas in CO₂ shielding gas is effective in the reduction of fume. The mechanism of the above phenomena can be generally explained on the basis of the fume formation mechanism previously proposed.
Increase of TiO₂, Fe-Si and Al₂O₃ or decrease of CaF₂ content in the flux, decreases the fume emission rate. The influence of iron power and Fe-Mn content is almost none. These variations of fume generation can be mainly explained by the vapor pressure of flux constituents.
The decrease of C content in the wire, especially in the wire sheath and lubricant, has an epochal effect in the reduction of fume. The reason of this phenomenon seems to be the restraint of the CO gas explosion in the droplets suspended at the tip of the wire.