Effect of TIG welding parameters on 316 L stainless steel joints using taguchi L27 approach

The AISI 316 L stainless steel was welded using Tungsten Inert Gas (TIG) welding, utilizing ternary shielding gases Argon (Ar), Helium (He), and Nitrogen (N₂). This study aimed to assess the effects of these ternary shielding gases on the microstructure, bead profile, and bead appearance. It provides a comprehensive grasp of welding parameters’ interplay with shielding gas compositions, enabling engineers to make informed choices that significantly influence the excellence, productivity, and lastingness of the welding process. The Taguchi L-27 approach was employed, incorporating different contents of N₂ (2.5 vol. % to 7.5 vol. %) and He (10 vol. % to 30 vol. %) within the Ar shielding gas composition. Additionally, welding current intensities, ranging from 120 A to 180 A, were also used in the experiment. The results demonstrated that higher content of He and N₂ resulted in elevated levels of austenite-forming elements. Therefore, for TIG welding at the arc current intensity of 150 A, it is recommended to utilize the shielding gas mixtures (2.5 vol. % N₂ + 10 vol. % He + 87.5 vol. % Ar). Furthermore, by augmenting the content of both N₂ and He within the Ar shielding gas mixture, in addition to adjusting the arc current, a notable expansion in both the width and depth of the weld profile was achieved. This achievement, in turn, played a pivotal role in securing comprehensive fusion throughout the welding process.