Modelling the crack growth behaviour of a single crystal nickel base superalloy under TMF loading with long dwell times

Abstract The influence of hold time on the crack growth behaviour of a single crystal nickel base superalloy under in-phase thermomechanical fatigue is investigated. Two da/dt models were calibrated using creep crack growth tests in the temperature range 750°C-950°C: one based on K and the other on (Ct)avg. The models were applied, in combination with a cycle dependent model, to predict da/dN of in-phase thermomechanical fatigue crack growth tests with 1h-6h hold time. The predictions based on K were inaccurate and generally non-conservative, whereas the predictions based on (Ct)avg were accurate. da/dt vs (Ct)avg followed a single trendline for all temperatures.