Low-cycle fatigue of TiNi shape memory alloy and formulation of fatigue life

The low-cycle fatigue of a TiNi shape memory alloy was investigated by the rotating bending fatigue tests in air, in water and in silicone oil. (1) Th e influence of corrosion fatigue in water does not appear in the region of low-cycle fatigue. (2) The temperature rise measured through an infrared th ermograph during the fatigue test in air is four times as large as that mea sured through a thermocouple. (3) The fatigue life at an elevated temperatu re in air coincides with the fatigue life at the same elevated temperature in water. (4) The shape memory processing temperature does not affect the f atigue life. (5) The fatigue equation is proposed to describe the fatigue l ife depending on strain amplitude, temperature and frequency. The fatigue l ife is estimated well by the proposed equation. [S0094-4289(00)01102-6].