Ultrasonic irradiation induced the microstructure refinement and texture evolution of Ti–6Al–4V TIG weld seam

A comparison of the U-TIG with the TIG showed that weld grain diameter obtained by U-TIG was refined. In the weld surface, the maximum grain size of U-TIG was decreased by 400 µm. In the weld cross-section, the maximum grain size of U-TIG (70∼80 µm) was decreased by more than three times. The texture intensity of the weld seam in the TIG was significantly greater than that of the weld seam in the U-TIG due to that the microstructure of the weld seam in the U-TIG was improved. In the U-TIG, the ultrasound cavitation and acoustic streaming were generated in the weld pool by the ultrasonic irradiation which was the main causes of the significant refinement of the weld grain and the reduction of texture intensity.