Influence of mean stress on ti6a14v fatigue crack growth at very high frequency

Abstract The present study deals with the fracture mechanics behaviour of a titanium alloy — Ti6A14V (TA6V french mark) in ultrasonic fatigue. Besides the development of corresponding experimental techniques, this paper presents firstly the finite element method calculation of stress intensity factor K I in ultrasonic fatigue with a positive mean stress; then fatigue crack growth (FCG) rates of Ti6A14V at high frequency at room temperature and with stress ratio R between -1 and 0-0.9. The thresholds are determined up to ca 10 −11 m/cycle. The fracture mechanisms have been observed and analyzed metallographically and microfractographically under a scanning electron microscope to compare with conventional fatigue. In adition, some cumulation experiments of ultrasonic fatigue with slow fatigue have been carried out.