Creep-fatigue interaction in two gas turbine Ni based superalloys subjected to service-like conditions

• Published in: Materials at high temperatures Vol. 31; no. 4; pp. 348 - 356
• Main Authors: Vacchieri, E., Holdsworth, S. R., Costa, A., Poggio, E., Riva, A., Villari, P.
• Format: Journal Article
• Language: English
• Published: Leeds Taylor & Francis 01.11.2014; Taylor & Francis Ltd
• Subjects: Creep-fatigue interaction; Cyclic hold test; Damage; Ductility exhaustion; Energy density; Fatigue tests; Finite element method; Gas turbines; Mathematical analysis; Ni based superalloys; Nickel; Strain energy density; Superalloys; Time fraction; TMF benchmark test
• ISSN: 0960-3409; 1878-6413
• DOI: 10.1179/0960340914Z.00000000052

Creep-fatigue interaction has been studied in single crystal and equiaxed Ni based superalloys, adopted for critical gas turbine component applications. Cyclic hold tests have been performed to understand the influence of creep damage and deformation on fatigue endurance, considering also the effect of the position of the hold time in the low cycle fatigue cycle. Service-like thermomechanical fatigue (TMF) benchmark tests have been carried out, involving TMF cycles based on the loading conditions at component critical locations determined by finite element (FE) simulation. Damage calculations have been performed on all the conducted tests for both materials, comparing results obtained by different methodologies (e.g. time fraction, ductility exhaustion, strain energy density). The results have been compared with actual in-service damage revealed by microstructural examination.