Bridging the gap between metallurgy and fatigue reliability of hydraulic turbine runners

27th IAHR Symposium on Hydraulic Machinery and Systems

Thibault, D.^1 ; Gagnon, M.^1 ; Godin, S.^1

Researchers, Expertise Mécanique, Métallurgie et Hydroéolien, Institut de Recherche d'Hydro-Québec (IREQ), Varennes

QC

J4J 5J9, Canada^1

关键词: Degradation mechanism;    Fatigue properties;    Fatigue reliability;    Microstructural features;    Physical parameters;    Physically based;    Reliability model;    Tolerance approach;   

Others  :  https://iopscience.iop.org/article/10.1088/1755-1315/22/1/012019/pdf
DOI  :  10.1088/1755-1315/22/1/012019

来源: IOP

【 摘 要 】

The failure of hydraulic turbine runners is a very rare event. Hence, in order to assess the reliability of these components, one cannot rely on statistical models based on the number of failures in a given population. However, as there is a limited number of degradation mechanisms involved, it is possible to use physically-based reliability models. Such models are more complicated but have the advantage of being able to account for physical parameters in the prediction of the evolution of runner degradation. They can therefore propose solutions to help improve reliability. With the use of such models, the effect of materials properties on runner reliability can easily be illustrated. This paper will present a brief review of the Kitagawa-Takahashi diagram that links the damage tolerance approach, based on fracture mechanics, to the stress or strain-life approaches. This diagram is at the centre of the reliability model used in this study. Using simplified response spectra obtained from on-site runner stress measurements, the paper will show how fatigue reliability is impacted by materials fatigue properties, namely fatigue crack propagation behaviour and fatigue limit obtained on S-N curves. It will also present a review of the most important microstructural features of 13%Cr- 4%Ni stainless steels used for runner manufacturing and will review how they influence fatigue properties in an effort to bridge the gap between metallurgy and turbine runners reliability.