Influence of superimposed vibrational load on dwell time crack growth in a Ni-based superalloy

•Fatigue crack growth modelling of dwell time effects.•Crack propagation testing and modelling.•Vibrational cycle interaction with sustained load.•Scanning electron microscopy of crack paths. Sustained loads have for some Ni-based superalloys been shown to give rise to increased crack growth rate at...

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Bibliographic Details
Published in:International journal of fatigue 2016-06, Vol.87, p.301-310
Main Authors: Storgärds, Erik, Saarimäki, Jonas, Simonsson, Kjell, Sjöström, Sören, Månsson, Tomas, Moverare, Johan
Format: Article
Language:English
Subjects:
Crack growth modelling
Crack propagation
Dwell time
Dwell times
Fatigue cracking
Fracture mechanics
High temperature
Inconel 718
Modelling
Nickel
Nickel base alloys
Superalloys
Vibration
Vibrational load
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Summary:•Fatigue crack growth modelling of dwell time effects.•Crack propagation testing and modelling.•Vibrational cycle interaction with sustained load.•Scanning electron microscopy of crack paths. Sustained loads have for some Ni-based superalloys been shown to give rise to increased crack growth rate at elevated temperature. Such loads generate a history dependent fatigue problem due to weakening and cracking of grain boundaries during dwell times, later broken apart during subsequent load cycles. So far most studies have focused on the interaction of load cycles, overloads, and temperature. However, vibrations of different kinds are to some extent always present in engine components, and an investigation of how such loads affect the dwell time cracking, and how to incorporate them in a modelling context, is therefore of importance. In this paper a study of the most frequently used gas turbine material, Inconel 718, has been carried out. Mechanical crack propagation testing has been conducted at 550°C for surface cracks with and without the interaction of superimposed vibrational loads. Subsequent investigation of the fracture behaviour was performed by scanning electron microscopy and the modelling work has been conducted by incorporating the vibration load description within a history dependent crack growth law. The obtained results show reasonable accuracy with respect to the mechanical test results.
ISSN:0142-1123
1879-3452
1879-3452
DOI:10.1016/j.ijfatigue.2016.02.018