Life Prediction of IN738LC Considering Creep Damage under Low Cycle Fatigue

As growing attention on greenhouse gas reduction, developing an eco-friendly power generation system of power plants and enhancing its efficiency has been actively researched. In order to increase the efficiency, the operating temperature has been raised, and hence the application of Ni-base super-alloy has increased to a core component of the power generation system like a turbine blade, a rotor and a boiler. Especially, turbine blades are exposed to high-temperature and high-pressure, and they bear mechanical loads due to the centrifugal force of the high-speed rotation. Thus, the durability of the blade material should be tested under high temperature conditions. In high temperature LCF tests, damage occurs in specimens because of creep. Hence, the aim of this study is to estimate the life of LCF precisely by considering the creep damage in specimens generated during the LCF test. We conducted the LCF tests to propose a new life prediction method considering the fatigue and creep damage. Finally, this study demonstrates the reliability of the prediction method by comparing the predicted life with the actual fatigue life. Through this, we expect to predict the fatigue life more accurately by predicting the fatigue life under different fatigue strain frequencies considering the creep damage.