Thermal fatigue of single-crystal superalloys: experiments, crack-initiation and crack-propagation criteria

Thermal-fatigue tests were performed on corset samples made from five single-crystal nickel-based superalloys with various crystallographic orientations (〈 〉 001 ,〈 〉 011 ,〈 〉 111 ) at different temperatures and cycle durations.The proposed criteria for the thermal-fatigue crack initiation and crack propagation are discussed and compared with experimental results.The sensitivity of durability to the crystallographic orientation and to thermal-cycle parameters is analyzed experimentally and by means of the corresponding finite-element simulations.