A COMPARISON STUDY ON MICRO-BULGING AND SHORTLESS PEENING PROCESSES USING WATER JET CAVITATION

Abstract

This paper presents a comparative study using a newly technology called water jets cavitation to fabricate micro feature on 304 stainless steel foils with a thickness of 100 µm and surface enhancement of 8090AlLi alloy sample with a thickness of 4 mm, where angular nozzle and a designed cavitation system were used with an incident pressure of 8-20 MPa. The bulged sample and the effect of incident pressure on the cavitation zone range were investigated. The experimental results indicated that the formed sample bulging depth of the outer ring shock zone and the bulging depth of the jet shock zone were not ideal, while the pits in the cavitation shock zone (that is, pits 2~4 and 10~12) obtained good geometric characteristics. Finally, the consistency of the maximum bulging depth was relatively good. The micro-bulged parts showed that the micro-pits in the cavitation shock zone had a large bulging depth and their uniformity was relatively good, indicating that the circular array feature micro-die has good performance in the cavitation water jet shock micro-bulging process. The effect of incident pressure on the range of cavitation zone, also indicated that the effective area of action of the cavitation water jet showed a ring. That is when the incident pressure was 20 MPa with a target distance of 120 mm, the maximum cavitation shock (bulging) zone showed rings of 3.5 ～21.1 mm with the 304 stainless steel foil and 3.5 mm~21.4 mm also with the 8090Al-Li alloy plate which were approximately same.