Several studies on the processing effects on NiTi fatigue were published in the recent past. However, there were disagreements and debates with respect to the interpretation on these results. In hope to provide a more comprehensive understanding on this issue, a study on the fatigue properties of NiTi wires, Ti-55.8/55.9 wt %Ni in composition, comparing the various effects of surface finishes and heat treatments was conducted using a rotating beam test method in a 37^oC water bath. This investigation covers the effects of various chemical, electrochemical as well as mechanical finishing methods on the fatigue properties of heat-treated NiTi wire. The effects of heat treatment parameters and the resulting transformation temperatures on NiTi fatigue were also studied. Where enough data was gathered S-N curves were generated for the various processing conditions. Surface, microstructure as well as fracture analyses were conducted to support the cyclic fatigue data.

Key Words: fatigue, S-N curves, rotating beam fatigue test, surface finishing, thermal mechanical processing