Metal vapor behavior in double electrodes TIG welding

In present paper，the metal vapour behavior in double electrodes TIG welding was investigated by a numerical model，including the arc plasma and weld pool．The thermodynamic parameters and transport coefficients of the arc plasma were dependent on both the local temperature and the mass ratio of the metal vapour．A second viscosity approximation was used to formulate the diffusion coefficient of the metal vapour in the arc plasma．The temperature and flow fields together with the metal vapour concentration were simulated，and the influences of metal vapour on the arc plasma and the weld pool were analyzed．It was found that the metal vapour transport in the arc plasma was significantly influenced by the flow of the arc plasma，and the distribution of the metal vapour was more extended in the direction perpendicular to the line through the double electrodes tips．Both the arc plasma and the heat flux at the weld pool were constricted by the presence of the metal vapour，while the metal vapour had a minor effect on the total heat input to the work piece and the weld pool profile as a whole．