Thermomechanical fatigue and life prediction method of a precision cast superalloy with electrical discharge machining drilled holes

Thermomechanical fatigue behavior of a directional solidified superalloy was investigated. Circular holes were designed on the specimen manufactured by precision cast method. The results indicated that the TMF damage is mainly controlled by fatigue, creep and oxidation damage, and the stress concentration at the holes results in crack nucleation and final failure. A new TMF life prediction method for specimens with stress concentration is proposed. The stress gradient is introduced to consider the effect of stress concentration at hole and notch in this method, which is verified by TMF data of smooth, notched and hole specimens.