Investigation on the Pulsed TIG Welding of Nickel-Base Alloy for Improved Microstructure and Weld Penetration

In this study, a novel pulsed tungsten inert gas (TIG) welding technique that is capable of effectively improving the weldabilities of nickel-based alloys was developed. The correlation between process parameters and material properties was studied. The effects of ratios of pulse to background welding currents on hardness and penetration in welds and heat-affected zones (HAZs) of Inconel 718 alloy were investigated experimentally by using the pulsed TIG welding technique. It is found that with an increasing ratio of the pulse to background welding current, the hardness in welds increased from 2% to 3.5%, compared to that in constant current TIG welding at the same level of heat input. When the ratio of pulse to background welding current is higher than 6, the penetration in weld was improved significantly by up to 61%. Research work has demonstrated that the pulsed TIG welding technique is an effective approach to control the microstructure and reduce cracking susceptibilities.