Improvement of fatigue strength by using cavitating jets in air and water

Peening method using cavitation impact at bubble collapse has been proposed. At the peening, cavitation bubble was normally generated by injecting a highspeed water jet into a water-filled chamber, i.e., a cavitating jet in water. In the present paper, the peening using a cavitating jet in air, which can generate the cavitation bubble without a water-filled chamber was investigated. It was revealed that the improvement of fatigue strength peened by the cavitating jet in air was better than that of the cavitating jet in water.