Application of ultrasonic cavitation to metal working and surface treatment of mild steel.

Cavitation, which causes erosion on metal surfaces, is regarded as harmful. But in this study, the phenomena of the cavitation were used positively for metal working, surface treatment and reviving "coined and shaved off" characters. In the experiments, cavitation was generated in the water by ultrasonic vibrations of 20 kHz. The main results are as follows. (1) "Coined and shaved off" characters on metal surface are revived by cavitation. (2) The fatigue limits of mild steels are increased by exposing the surface to the cavitation flow. (3) It is clarified that the erosion working by the radiation of cavitations is useful for cutting work. The relations among the shapes of terminal rods of a vibration system, the working conditions of the process and the erosion patterns are also clarified. (4) The vibration mode of the terminal rods that are specially designed for generating cavitation are analyzed by F. E. M..