Very high cycle fatigue of a nickel-based superalloy at room and elevated temperatures: Interior failure behavior and life prediction

Asymmetric load tests at 25 °C & 750 °C were performed to clarify the high-cycle-fatigue and very-high-cycle-fatigue properties of a nickel-based superalloy at elevated temperature. The life at 750 °C is longer due to the interior failure with crystallographic facets. Moreover, due to the competition between temperature and vacuum effects, threshold values for small and long cracks, as well as the transition crack size, are all lower at elevated temperature. Finally, based on proposed crack nucleation life model, fatigue life is evaluated by using fatigue-index-parameter, and predicted results are within a factor of three with respect to experimental data.