Development of a new ratcheting fatigue life prediction model of a nickel-based superalloy based on ratcheting strain rate

Abstract

The stress-controlled low cycle fatigue and ratcheting fatigue behaviors of a nickel-based superalloy were proposed under a series of symmetric and asymmetric cyclic loadings at 650 °C to explore the effects of stress amplitude and mean stress on fatigue life. The results show that ratcheting strain increases with cycle numbers increasing. Ratcheting strain rate curves exhibit three different stages including deceleration, steady state and acceleration growth stage. A fatigue life prediction model based on the ratcheting strain rate considering stress amplitude and mean stress was conducted to predict the fatigue life. The predicted fatigue life agrees with the measured fatigue life very well, and all the data points are located in 1.25X scatter band based on the model.