Shielding gas influence on emissions in arc welding

Abstract

In arc welding, particulate and gaseous as well as electromagnetic emission are generated. Users are mostly aware of the particulate fumes and therefore their risks are questioned and discussed. Gaseous emissions like NO, NO2, and O3 were either little noticed or the extent of their toxic effect were not fully recognized in the past. However, the awareness of their hazardous potential led to a decrease of the threshold limits. A fundamental understanding is needed to be able to avoid the formation of these gaseous emissions effectively. In this article, the radiation behavior for TIG-arcs and the interaction with the ozone formation is systematically investigated for different process gas components. Furthermore, the role of metal vapor in a TIG arc is clarified and the impact on the ozone formation is studied by using molten and none molten anodes. The results of the investigation show that a helium concentration of more than 80% has a significant influence on the characteristic arc radiation and as a result on the ozone formation.