The effect of activating fluxes on 316L stainless steel weld joint characteristic in TIG welding using the Taguchi method

Gas tungsten arc welding is fundamental in those industries where it is important to control the weld bead shape and its metallurgical characteristics. However, compared to the other arc welding process, the shallow penetration of the TIG welding restricts its ability to weld thick structures in a single pass (~ 2 mm for stainless steels), thus its productivity is relativity low. This is why there have been several trials to improve the productivity of the TIG welding. The use of activating flux in TIG welding process is one of such attempts. In this study, first, the effect of each TIG welding parameters on the weld’s penetration depth was shown and then, the optimal parameters were determined using the Taguchi method with L9 (34) orthogonal array. SiO2 and TiO2 oxide powders were used to investigate the effect of activating flux on the TIG weld penetration depth and mechanical properties of 316L austenitic stainless steel. A camera was used to observe and record images of the welding arc, and analyze the relationship between increasing the penetration depth and arc profile. The experimental results showed that activating flux aided TIG welding has increased the weld penetration, tending to reduce the width of the weld bead. The SiO2 flux produced the most noticeable effect. Furthermore, the welded joint presented better tensile strength and hardness.