Influence of Current and Shielding Gas in TiO2 Flux Activated TIG Welding on Different Graded Steels

In tungsten inert gas (TIG) welding, limited depth of penetration can be achieved during single pass welding. To achieve the desired depth of penetration, the speed of welding needs to be significantly reduced and hence, the productivity decreases. In the present work, the effect of TiO2 activated flux on penetration is evaluated for different workpieces namely AISI 1020, AISI 304, AISI 316, and Duplex 2205 steels at different currents and shielding gas compositions. The results show a significant increase in the depth of penetration and reduction in the width-to-penetration ratio using the activated flux for all the workpiece materials considered here. Current increases the depth of penetration, however, the influence of flux becomes more significant with higher welding current. Maximum of 37.8%, 44.3%, 47%, and 124% increase in depths of penetration is measured for AISI 1020, AISI 304, AISI 316, and Duplex 2205 steels, respectively, when activated flux is used. Also, maximum of 70% increase in the depth of penetration is further achieved when Ar along with 5% H-2 is used as the shielding gas compared to that when pure Ar is used. The constriction of arc column increases the energy density, which increases the depth of penetration. Measurement of microhardness and metallurgical observations are carried out for samples after TIG welding and activated tungsten inert gas (ATIG) welding and compared to observe the solidification phenomenon during the process.