Fatigue Enhancement Of Shape Set NiTi Components Via Micro Peening

Micro peening is examined as a way to improve the functional performance of Nitinol shape set components.  Fatigue life improvements in micro peened, super elastic NiTi have been observed when samples were rotary beam fatigue tested in a body temperature environment.   This presentation will explore differences in the fatigue life of micro peened and untreated shape set NiTi.  Three, binary nominally Ni-49.2 at.% Ti, melt sources are evaluated using drawn 0.58 mm diameter wire that is shape set into a med device-relevant  z-shaped ring.  The rings are mechanically cycled via a zero-stress ratio fatigue test in a body temperature saline environment using a Bose® 3200 Series test instrument.  These data reveal micro peening as a promising technology to improve fatigue life and stress-corrosion resistance of shape memory components due to the generation of compressive surface stresses.