Visualizations of fluid flows in the TIG welding region for different shapes of the shield gas nozzle

Abstract  

The tungsten inert gas (TIG) welding enables to produce high welding qualities. However, it has some problems such as a large distortion and a shallow penetration into the welding parts. To overcome those problems, there have been many studies on A-TIG welding in which active flux and a shield gas are used. The shield gas pressure, velocity, and distribution area are dominant factors in producing better welding condition which can be evaluated by the gas penetration, the gap between the nozzle tip and welding plate and the nozzle shape of the shield gas. In this study, the influences of the shield gas distribution onto the melting efficiency and penetration shape in TIG welding were investigated using a numerical simulation. The gap distances between the nozzle tip and the welding plate were changed 3, 4, 5 mm and two nozzle shapes, convergent parallel (CP) and CDP, were tested. 100% Ar gas was used as the shield gas. CDP type nozzle showed deeper penetrations and higher melting efficiency compared to those of CD type and CP type nozzles.