A Study on Fatigue Life Prediction of Ni-base Superalloy

A gas turbine blade rotates at high speed in a high-temperature flame, degradation environment under mechanical loading. It is also exposed to a thermo-mechanical fatigue environment caused by frequent starts and shutdowns. Therefore, the life of the blade material should be evaluated considering such various factors.In this study, the low cycle fatigue(LCF) and thermo-mechanical fatigue(TMF) tests were carried out by using a furnace, which directly transfer heat flux, for the life prediction of a Ni-base superalloy. LCF tests were conducted over a wide range of strain conditions considering the gas turbine operating condition. Also, IP (in-phase) and OP (out of-phase) TMF tests were conducted over a wide range of strain conditions. Finally, a fatigue life prediction model of the Ni-base superalloy was obtained from the LCF and TMF test results. And also, a comparison between the LCF and TMF test results was evaluated with respect to fatigue life.