Improvement of Formation, Microstructure and Mechanical Properties of TIG Welded TC4 Titanium Alloy by Ultrasonic Coaxial Radiation

In this study, the effects of ultrasonic coaxial assisted TIG welding (U-TIG) on the formation, microstructure, and mechanical properties of TC4 titanium alloy welded joints were investigated. The results indicated that at optimal ultrasonic power and welding current settings, remarkable improvements of welded joint were observed. Specifically, the weld depth-to-width ratio increased by 267% compared to conventional TIG welding, reaching 0.22. Furthermore, the microhardness of the welded seam increased by 53%, reaching 550.1 HV, while the tensile strength of the welded joint rose to 1197.7 MPa, representing a 12.2% enhancement. The compressing effect of ultrasound concentrates the energy of the arc, thereby improving the penetration depth of the welded seam. In addition, ultrasonic cavitation plays a crucial role in refining the grain structure of the weld seam, consequently enhancing its strength.