Experimental Investigation of TIG Welding Ti-6Al-4V by using different supply mixture ratio of Ar-He Shielding Gas

Ti-6Al-4V is a material that is extensively used in the gas turbine application. The fabrication of the assemblies of the gas turbine made up of Ti-6Al-4V involves Tungsten Inert Gas (TIG) welding. It is preferred to have a minimal bead width for minimal distortion with full penetration welds meeting the required weld quality as per aerospace weld standards. The primary purging gas which is usually employed during TIG welding is inert argon gas. In this present study argon and helium gas mixture was adopted as shielding gas. Taguchi design of experiment has been employed involving L9 orthogonal array with 3 parameters and 3 levels. The aim of the study was to understand the effect of the weld parameters and Ar-He gas mix ratio on the bead width of the welds. The obtained results were analyzed using ANOVA and found the welding current having significant effect on bead width followed by welding speed and Ar-He gas mix. A linear regression mathematical model is generated of the response variable. In order to ascertain the optimized parameters confirmation tests are conducted and obtained results are correlated. Macroscopic images do not show any crack or porosity and thereby confirm that defect free welds can be produced within the range of process parameters.