Effect of Peening Process on Corrosion Fatigue Life for TiNi Shape Memory Alloy

Abstract

The effect of ultrasonic shot peening on corrosion fatigue properties of a TiNi shape memory alloy was investigated. In this study, the surface condition of the peened specimens was optically observed and the arithmetic mean roughness of the specimen surface was measured. The main points of the results obtained in this study are as follows: (1) The surface roughness of as-peened specimen decreases with increasing the peening coverage because of smoothing effect by shot media. (2) Surface roughing derived from adhesion of Fe in the shot media was observed on the as-peened specimen, especially under high coverage conditions. (3) Mechanical polishing after the peening reduces the surface roughness to the level before peening. (4) No change was observed on the specimen surface even if the peened and then polished materials were heated to induce the reverse transformation.