Optimization of GTAW process parameters for deposition of nickel-based hardfacing alloy using Taguchi method

Nickel-based hardfacing alloys are widely used for the prevention of corrosion and wear losses in various industrial applications. They are prepared by various processes, and their properties are dependent on process parameters. In this study, the ERNiCr-B hardfacing alloy was deposited on AISI 304 stainless steel substrate using gas tungsten arc welding (GTAW) process using various processing parameters. Process parameters, namely, current, pre-heating temperature, and shielding gas flow rate of the GTAW process were optimized via Taguchi method. Confirmation test proved the validity of the optimization method. The optimum values of current, pre-heating temperature, and gas flow rate of the GTAW process for the deposition of ERNiCr-B hardfacing alloy on the 304 stainless steel substrate with respect to bead reinforcement were 130 A, 303.15 K, and 0.00015 m³/s, respectively. At optimum deposition condition, no evidence of defects such as microcracks, porosity, inclusions, etc. were observed in the hardfaced alloy. Among various parameters, the current had the most significant effect on dependent variables such as bead width, reinforcement height, hardness, and corrosion resistance of hardfaced deposit. Microstructural examination showed a typical dendritic structure with eutectic phases distributed in the inter-dendritic regions. Furthermore, the energy-dispersive X-ray spectroscopic (EDS) analysis showed the evidence of Fe dilution in ERNiCr-B deposit away from the substrate, which showed profound effect on hardness, microstructure, and corrosion rate.