Ultrasonic vibration assisted gas tungsten arc welding of Inconel 690 alloy: Ultrasonic effect to refine grains and improve mechanical properties.

The Inconel 690 alloy is widely used in the manufacturing of nuclear equipment, such as pipe welding for steam generators (SG) and pressure vessels, due to its excellent high-temperature strength, corrosion resistance, and thermal stability. However, coarse grains have been observed in the welded joint of Inconel 690. Considering its crucial role as a structural material under high pressure, temperature, and corrosive conditions, improvements should be made to the microstructure of the welded joint.

Heat Source Characteristics of Ternary-Gas-Shielded Tandem Narrow-Gap GMAW.

The characteristics of the welding heat source for tandem narrow-gap gas metal arc welding are examined for different ternary shielding gas (Ar-CO-He) compositions. Results of previous calculations of arc properties for bead-on-plate geometry are adapted to the narrow-gap geometry to predict these characteristics. The heat source concentration factor decreases and the maximum heat flux density increases as the helium content increases, which leads to an increased welding heat efficiency.