Fume formation from spatter oxidation during arc welding

Spatter and fume formation rates during arc welding both increase and decrease in a similar manner as welding parameters change. Previously, this fume - spatter relationship has been attributed to evaporation of the spatter caused by oxidation. In this work, a simulated spatter oxidation test did not detect significant fume formation, but high speed videography showed fume trails behind large spatter droplets. Heat balance calculations show that only spatter droplets larger than a few millimeters evaporate and produce fume in significant amounts. Since most spatter particles are smaller than 2 mm, it is not likely that evaporation from spatter contributes significantly to fume. It is proposed that the correlation between spatter and welding fume is instead related to how the temperature of the welding surface affects formation rates of both spatter and fume.