Creep, Fatigue, and Oxidation Interactions During High and Very High Cycle Fatigue at Elevated Temperature of Nickel-Based Single Crystal Superalloys

TitleCreep, Fatigue, and Oxidation Interactions During High and Very High Cycle Fatigue at Elevated Temperature of Nickel-Based Single Crystal Superalloys
Publication TypeConference Paper
Year of Publication2020
AuthorsCervellon A., Yi J.Z, Corpace F., Hervier Z., Rigney J., Wright P.K, Torbet C.J, Cormier J., Jones J.W, Pollock T.M
EditorTin S, Hardy M, Clews J, Cormier J, Feng Q, Marcin J, O'Brien C, Suzuki A
Conference NameSuperalloys 2020
ISBN Number9783030518349
KeywordsCreep, fatigue, High temperature, Superalloy
Abstract

High-temperature fatigue of Ni-based single crystal superalloys is studied at 1000 °C in a wide range of loading conditions (−1 ? R ? 0.8) and number of cycles (103 − 109). Under fully reversed conditions, a competition between crack initiations from the surface— assisted by oxidation—and from internal metallurgical defects—mostly large casting pores—is observed. Increasing the testing frequency shifts the competition to a higher number of cycles. Conversely, decreasing the casting pore size or coating the specimen promotes surface initiations. When a positive mean stress is added (R ? 0), a creep deformation/damage mechanism mainly controls fatigue life, despite fracture surfaces presenting a variety of initiation types. Fatigue life can be predicted by a simple creep law if the contribution of the alternating stress is considered. A linear damage summation method that considers pure fatigue and pure creep damage is used to predict the fatigue lives, and Haigh diagrams for different alloys are presented.

URLhttp://dx.doi.org/10.1007/978-3-030-51834-9_65
DOI10.1007/978-3-030-51834-9