Nishio Kazumasa

Computational fluid dynamics analysis of shielding gas behaviour in tungsten inert gas welding of titanium plate

To minimize the volume of argon required for on-site TIG welding of titanium plate, we investigated the behaviour of argon flow in a trailing-shielding box by means of computational fluid dynamics (CFD) simulations. In this study, we designed a model of a solid rectangular shielding box consisting of 9.5 × 105 tetrahedral elements. Then, argon flow was simulated for various shielding parameters, namely the gap between the box and floor and the argon supply rate. In an experiment using dry ice mist to visualize the flow of argon, we investigated the flow from a shielding box model consisting of acrylic plates for various shielding parameters. In this manner, we studied the relation between the oxygen content in the shielding box and the shielding parameters. Then, a conventional shielding box and a prototype shielding box were evaluated experimentally. We confirmed the relation between the oxygen content in the shielding boxes and the degree of oxidation on the bead surface in TIG arc melt-run welding of titanium plate. The experimental results show that the simulation model used in the CFD simulations allowed the behaviour of argon to be predicted. We conclude that the simulation model is useful for improving the structure of the shielding box.