Ultrasonic-assisted Pulsed TIG Welding (U-P-TIG) of Inconel 690 for Nuclear Power Plants

Abstract

Abstract Inconel 690 has been extensively used in steam generator tubing materials for pressurized water reactors. In order to improve the weld quality of Inconel 690, ultrasonic-assisted pulsed tungsten inert gas (TIG) welding is studied. In this study, the macrostructure, microstructure, and mechanical properties of Inconel 690 weldments welded by TIG welding with and without ultrasonic assistance were investigated. The microstructures of the fusion zone (FZ) and heat-affected zones (HAZ) were examined by an optical microscope and the Electron Backscatter Diffraction (EBSD) technique, and weldment properties were compared through tensile and impact tests. Experimental results indicate that the base metal (BM) was composed of equiaxed crystalline austenite, and the austenite grains in the heat-affected zone were obviously grown; the fusion zone (FZ) was composed of columnar austenite. Besides, the ultrasonic assistance was effective in refining the structure and improving the strength and toughness of weld metal.