Microstructure and properties of solid state joints of titanium sheets produced by ultrasonic welding

Abstract

The results of the study on the microstructure and properties of solid state joints of titanium sheets obtained by ultrasonic welding (USW) with frequency 20 kHz and vibration amplitude 20 µm during 2 and 3 s under a 6 kN clamping force are presented. The thermo-mechanically affected zone is observed along the defect-free weld line (joint). It was found that the length and width of this zone increased with the welding time. In the thermo-mechanically affected zone, a significant grain growth takes place, a change in the texture is observed and maxima near 60° and 90° in the grain boundary misorientation distributions appear. The maximum lap shear failure load of the joints obtained by USW of 2 and 3 s durations are 1998±122 and 2506±226 N, respectively. There is a change in the failure mode from interface debonding after 2 s USW to nugget pull-out for the welding time of 3 s.