Creep-fatigue lifetime prediction of GH720Li superalloy considering effect of grain size
(1. Hangzhou International Innovation Institute, Beihang University, Hangzhou 311115, China;
2. Research Institute of Aero-engine, Beihang University, Beijing 100191, China;
3. Beijing Key Laboratory of Aero-engine Structure and Strength, Beijing 100191, China;
4. United Research Center of Mid-Small Aero-engine, Beijing 100191, China;
5. School of Aerospace Engineering, Tsinghua University, Beijing 100084, China;
6. Hunan Aviation Powerplant Research Institute, Aero Engine (Group) Corporation of China, Zhuzhou 412002, China;
7. Hangzhou Turbine Power Group Co., Ltd., Hangzhou 310000, China;
8. Failure Mechanics and Engineering Disaster Prevention, Key Laboratory of Sichuan Province, Sichuan University, Chengdu 610065, China)
2. Research Institute of Aero-engine, Beihang University, Beijing 100191, China;
3. Beijing Key Laboratory of Aero-engine Structure and Strength, Beijing 100191, China;
4. United Research Center of Mid-Small Aero-engine, Beijing 100191, China;
5. School of Aerospace Engineering, Tsinghua University, Beijing 100084, China;
6. Hunan Aviation Powerplant Research Institute, Aero Engine (Group) Corporation of China, Zhuzhou 412002, China;
7. Hangzhou Turbine Power Group Co., Ltd., Hangzhou 310000, China;
8. Failure Mechanics and Engineering Disaster Prevention, Key Laboratory of Sichuan Province, Sichuan University, Chengdu 610065, China)
Abstract: In order to accurately evaluate the creep-fatigue lifetime of GH720Li superalloy, a lifetime prediction model was established, reflecting the interaction between creep damage and low-cycle fatigue damage. The creep-fatigue lifetime prediction results of GH720Li superalloy with an average grain size of 17.3 μm were essentially within a scatter band of 2 times, indicating a strong agreement between the predicted lifetimes and experimental data. Then, considering that the grain size of the dual-property turbine disc decreases from the rim to the center, a grain-size-sensitive lifetime prediction model for creep-fatigue was established by introducing the ratio of grain boundary area. The improved model overcame the limitation of most traditional prediction methods, which failed to reflect the relationship between grain size and creep-fatigue lifetime.
Key words: creep-fatigue; lifetime prediction; GH720Li superalloy; grain size; damage accumulation