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Sustained macroscopic deflected fatigue crack growth in nickel based superalloy 720Li
conference contribution
posted on 2014-03-14, 14:26 authored by C. Schoettle, Philippa A.S. Reed, M.J. Starink, I. Sinclair, Daniel Child, Geoff West, Rachel ThomsonRachel ThomsonSustained deflected crack growth is a concern as we need to understand both the factors which cause it and when it may happen in a component to ensure we have appropriate lifing strategies in place. This behaviour has been reported in a number of fine-grained Ni-based turbine disc alloys at intermediate temperatures (200-600°C). Such fracture surfaces show a competition between opening and shear modes of crack growth, with macroscopic deflection being initiated from the free surface. The interaction of the crack and surrounding microstructure have been studied via serial sectioning using a focused ion beam, allowing a reconstruction based on combined 3D electron back scatter diffraction (EBSD) and energy dispersive spectroscopy (EDS) to be produced. This showed both intergranular and transgranular crack growth modes occurring in the deflected crack growth and no obvious influence of grain orientation or texture to explain the crack deflection. Visualisation and representation of such data-rich images is challenging - the additional compositional (phase identification), orientation and deformation/strain mapping features of this approach together with the spatial information in 3D may require new approaches to data presentation.
Funding
Funding support for C. Schoettle and D.J. Child from the Engineering and Physical Sciences Research Council and Rolls- Royce plc is gratefully acknowledged.
History
School
- Aeronautical, Automotive, Chemical and Materials Engineering
Department
- Materials
Citation
SCHOETTLE, C. ... et al, 2012. Sustained macroscopic deflected fatigue crack growth in nickel based superalloy 720Li. IN: Huron, E.S. et al (eds). Superalloys 2012: 12th International Symposium on Superalloys, Seven Springs, PA. John Wiley and sons, pp. 395 - 402Publisher
© John Wiley and sonsVersion
- AM (Accepted Manuscript)
Publication date
2012Notes
This conference paper is closed access.ISBN
9780470943205Language
- en