Optimization of Welding Process Parameters for Activated Tungsten Inert Welding of Inconel 625 Using the Technique for Order Preference by Similarity to Ideal Solution Methodology

This investigation aims to recognize the advanced input parameters for Inconel 625 by activated tungsten inert gas (A-TIG) welding. Bead on trial experiments was conducted with desirable input parameters such as welding current, torch travel speed, and arc gap according to the Taguchi L 25 orthogonal array. The aspect ratio of weld geometry and Brinell hardness (HB) were considered the output parameters. Technique for order preference by similarity to ideal solution (TOPSIS) is a multi-criteria decision-making approach to select an optimum combination of input responses. A step-by-step approach to the application of TOPSIS was followed in this study. Exploratory preliminaries revealed that welding current (300 Amps), torch travel speed (75 mm/min), and arc gap (1 mm) initiated optimum input parameters with optimum conditions of hardness (262 HB) and an aspect ratio of 0.421. Optimized weld zone microstructure and scanning electron microscope (SEM) with energy-dispersive X-ray spectroscopy (EDS) analysis were undertaken for a complete report on the migration of Nb atoms towards the weld zone. From the attained outcomes, it was inferred that a faster cooling rate in A-TIG welding leads to the suppression of the laves phase which could be due to an activated flux combination.