Hot Wire Gas Tungsten Arc Welding (HW-GTAW) is an improved version of cold wire GTAW (CW-GTAW). Preheating the filler wire in the HW-GTAW increases the deposition rate and improves process efficiency. In the present work, an indigenous HW-GTAW setup was developed (termed as HM-GTAW), which utilizes the intrinsic heat losses as conduction through the tungsten electrode and radiation through the welding arc to preheat the filler wire without using external power source. Deposition capability was up to three times higher with complete intermixing of the filler wire into the base plate using this method compared to CW-GTAW. The utilization of heat improves process efficiency and enhances weld bead dimensions when compared to the CW-GTAW process while using the same set of process parameters. The electron backscatter diffraction analysis indicates that with increasing heat input there is coarsening of grains and preponderance of low-angle grain boundaries. The higher wire feed speed decreases the available heat per unit melt volume, thereby inhibiting grain growth. This improves the percentage of high-angle grain boundaries leading to comparatively refined weld microstructure and correspondingly higher hardness than the higher heat-input case. The proposed setup provides a cost-effective alternative for energy-conscious industries.
Singh et al. (Sun,) studied this question.