Effects of ac arc ultrasonic on plasma arc in situ welding of SiCp/6061Al MMCs

The isolation coupling device is designed based on the principle of high pass filter circuit, which can achieve isolation and coupling between ac welding power and ultrasonic frequency excitation source. In addition, ac arc ultrasonic vibration is obtained successfully. The plasma arc in situ welding of SiCp/6061Al was performed using two different processes. The first process is that the plasma gas is argon nitrogen mixture and the filler material is flux cored wire (Al–5Ti–5Si); the other process is that the plasma gas is argon and the filler material is flux cored wire (Al–15Ti–3Si). The two joints are respectively enhanced by nitride and Al₃Ti, which were obtained in these processes. After arc ultrasonic vibrations were imposed on the two welding processes, it was revealed that arc ultrasonic improved the distribution of the new nitride phases and optimised the morphology of Al₃Ti to improve the mechanical properties of joints that reached 246 and 263 MPa. Fracture analysis showed that the improvement of the mechanical properties resulting from Al₃Ti is better than that from nitride under the effect of arc ultrasonic.