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|Title: ||Investigation of creep damage and cavitation mechanisms in P92 steels|
|Authors: ||Gu, Y.|
Thomson, Rachel C.
|Editors: ||Gandy, D.|
|Issue Date: ||2014|
|Publisher: ||© ASM International|
|Citation: ||GU, Y. ... et al, 2014. Investigation of creep damage and cavitation mechanisms in P92 steels. IN: Gandy, D. and Shingledecker, J. (eds). Advances in Materials Technology for Fossil Power Plants: Proceedings from the Seventh International Conference (EPRI 2013), 22nd-25th October 2013, Waikoloa, Hawaii, USA. ASM International, pp. 596 - 606.|
|Abstract: ||In typically processed creep stress enhanced ferritic steels (CSEF) it has been observed that the
long term performance and creep rupture strength is below that predicted from a simple
extrapolation of the short term creep data. One of the primary microstructural degradation
mechanisms responsible for this behaviour is the development of creep voids. Nucleation, growth
and interlinkage of voids will also result in a significant loss of creep ductility.
In this study, the cavities in creep tested P92 steel have been characterised. It has been found that
in the standard P92 samples studied, the cavities are associated with large (typically 1-2 μm)
ceramic particles. Three particle compositions were observed and more detailed TEM
investigations showed that these particles were BN, MnS and γ-Al2O3. Statistical analysis of the
ceramic particle types showed that in all samples studied a very high proportion of the cavities
was associated with BN particles. The shape of both the cavity and associated particle were
studied in 3D using a Focussed Ion Beam/ Field Emission Gun Scanning Electron Microscope
(FIB-FEGSEM) ‘slice and view’ technique. This showed that both the cavity and associated
particle had very irregular shapes.
Analysis in the head-gauge transition area of a creep test bar, where the exposure stress is low,
showed small cavities associated with the BN particles. This provides strong evidence that the
cavities were preferentially nucleating on the hard, irregularly shaped BN particles.|
|Description: ||Copyright 2014 ASM International, www.asminternational.org. This article was published in Advances in Materials Technology for Fossil Power Plants: Proceedings from the Seventh International Conference and is made available as an electronic reprint with the permission of ASM International. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplications of any material in this article for a fee or for commercial purposes, or modification of the content of this article is prohibited.|
|Sponsor: ||The authors would like to thank EPRI for the support of this project.|
|Version: ||Accepted for publication|
|Appears in Collections:||Conference Papers and Presentations (Materials)|
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