Influence of Shielding Gas on Fume Formation Rate for Gas Metal Arc Welding (GMAW) of Plain Carbon Steel

Shielding gas composition is an important parameter for successful gas metal arc welding (GMAW) and has been shown to affect the fume formation rate (FFR). The present paper compares thirteen shielding gases and their impact on FFR in spray transfer. In Ar-based mixtures, increasing CO(2) had a greater impact than raising O(2) on FFR. When O(2) was increased in ternary mixtures, the FFR increased for Ar-5%CO(2) but no discernable increase was observed for the Ar-12%CO(2) mixtures. Ar-He-CO(2) mixtures had the most stable FFR's. The FFR for 100% CO(2) was significantly higher due to the change in weld transfer mode to globular and increased spatter. Results indicate that CO(2) additions in Ar-based shielding gases are the controlling factor in determining FFR due to the effect of CO(2) on welding arc characteristics. There was no obvious influence from the shielding gas on particle composition and fume particles were identified as (Fe,Mn)(3)O(4).