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- 2014 (6) (entfernen)
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- Creep (2)
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- Fatigue at high temperature (2)
- LCF (2)
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Material modelling and lifetime prediction of Ni-base gas turbine blades under TMF conditions
(2014)
Under cyclic thermomechanical loading conditions, various damage mechanisms such as strain accumulation, creep cavitation, ageing, fatigue surface cracking etc. may take place in the material of a gas turbine blade. Depending on the loading conditions, all these effects can contribute to reduce the lifetime of the component. Subject of the present work is the development of a material model to describe the mechanical effects mentioned above, as well as the development of a lifetime model able to discriminate the different damage mechanisms.
The continuing increase of steam parameters of fossil fuelled high efficiency power plants and new combustion concepts for the capture and storage of carbon dioxide lead to harsher service conditions for the components and structural materials of such facilities. The present work introduces a test concept that allows testing of candidate materials under simultaneous mechanical and corrosive loading. The material's reaction can be directly investigated under simulated temperature, load and corrosion conditions of modern installations. First results obtained for different heat resistant steels suggest a strong influence of the environmental medium on the fatigue and creep behaviour. Such findings complement the data that is available from the classical qualification process of the materials and may support the material selection for new power plant installations.
Bei der isothermen und nichtisothermen Ermüdung (LCF und TMF) von warmfesten Gusseisenwerkstoffen wird mit zunehmender Dauer der Ermüdungsbelastung eine Schädigung des Werkstoffes infolge der mechanischen und thermischen Belastung in Form von plastischer Verformung, Rissbildung und -Wachstum, Porenbildung und Oxidation beobachtet. Diese Schädigungen führen vor dem eigentlichen Versagen (Probenbruch) zu einer signifikanten Verringerung der Steifigkeit. Am Beispiel des warmfesten austenitischen Gusseisens mit Kugelgraphit EN-GJSA-XNiSiCr35-5-2 werden Untersuchungen zum Einfluss der verschiedenen Schädigungsarten auf die Änderung der Steifigkeit vorgestellt.
Under cyclic thermomechanical loading conditions, various effects such as strain accumulation, creep damage, ageing, fatigue etc. may occur in the material of a gas turbine blade. Depending on the loading conditions, all these effects contribute to reduce the lifetime of the component. Subject of the present work is the development of a lifetime model able to discriminate between the different damage mechanisms, as well as the development of a material model to describe the mentioned effects and thus providing the input data for lifetime prediction.