抄録
The surface of a TiNi shape memory alloy (SMA) tape was treated by ultrasonic shot peening (USP), and the influence of the USP on the bending fatigue properties was investigated. The results obtained can be summarized as follows. (1) If SMA was shot-peened, the fatigue life becomes longer. The larger the bending strain amplitude, the shorter the fatigue life is. If the coverage of the USP is large, the bending fatigue life becomes longer. (2) The coverage of USP affects the fatigue life markedly. However, the influence of the diameter of the peening ball on the fatigue life is slight. (3) The larger the coverage of USP, the higher the Vickers hardness is. The fatigue life is proportional to the Vickers hardness at all strain amplitudes. (4) In the case of non-shop peened SMA tape, the fatigue crack nucleates at a certain point in the central position of the surface of the tape. In the case of shot peened SMA, the crack nucleates at a corner of the tape and propagates towards the center and along the surface of the tape with the higher speed of progression.
