Heat transfer decrement affected by lateral gas flow velocity in TIG arc welding

Abstract

TIG(Tungsten Inert Gas) arc welding is high quality joining technology. Therefore, it is used for welding of large buildings such as bridges and ships. However, it has been researched that the arc deflects to leeward side when the lateral gas flow velocity increases excessively to the arc1. In this case, the welding defects may occur because the heat transfer decreases. The heat conduction and electron inflow are dominant in the heat transfer to the anode2. Accordingly, it is considered that the heat conduction decreases to the anode because the temperature of the arc circumference is cooled by the lateral gas flow near the anode. However, the central part of the current density increases because the current path is narrowed. Therefore, it is considered that the electron inflow increases. Few reports have researched about the balance of the heat transfer when the lateral gas flow velocity is changed. In this paper, the heat transfer decrement affected by the lateral gas flow velocity in TIG arc welding is elucidated. The heat conduction and electron inflow to the anode are calculated by using the EMTF(electrical magnetic thermal fluid) simulation when the lateral gas flow velocity is changed. As a result, the heat transfer decreases because of the heat conduction decrement to the anode.