Optimization of TIG Welding Parameters for Ti-6Al-4V Titanium Alloy using the Taguchi Design of Experiment

This paper presents the effect of tungsten inert gas welding parameters (i.e. welding current, welding speed and filler wire speed) on weld bead geometry, notch tensile strength (NTS) and weld bead hardness of 2.0 mm thick annealed Ti6Al4V titanium alloy sheet welded in a square butt joint configuration using Taguchi L9 (33) three level - three factor matrix. Taguchi’s signal to noise ratios was calculated to obtain optimum welding parameters for Vickers hardness at weld area, Notch tensile strength (NTS), Front bead width (FBW) and Front reinforcement height (FRH). Analysis of Variance (ANOVA) was conducted to find statistically significant and insignificant factors with respect to each response. It was noted that welding speed has significant effect on weld hardness, notch tensile strength, front bead width and height. Optimum parameters for hardness were found to be 120A current, 400 mm / min welding speed and 250mm/min filler wire speed. Confirmation test using the optimal levels of welding parameters was also conducted in order to compare predicted results with values obtained through experimentation.