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

Abstract

The AISI 316L 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 120A to 180A were also used in the experiment. The results demonstrated that a higher content of He and N2 resulted in elevated levels of austenite-forming elements. Therefore, for TIG welding at the arc current intensity of 150A, 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.