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Modelling and experimental studies of alternative heat treatments in Steel 92 to optimise long term stress rupture properties

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journal contribution
posted on 2010-03-04, 13:32 authored by Youfa Yin, Roy G. Faulkner, P.F. Morris, P.D. Clarke
The desire for power plant to give increased generating efficiency and decreased CO2 emission has led to considerable effort over the last 10-15 years, to develop ferritic-martensitic steels which can be used for steam temperatures up to about 650°C. Examples are the addition of boron and increasing chromium content to 10-12 wt-%. However, high chromium levels have led to problems with long term precipitate stability. One approach which has not been widely explored, is the use of novel heat treatments to optimise the preservice microstructure to give the best long term creep rupture strength. Increased austenitising temperatures and lower tempering temperatures have been examined in Steel 92 (9Cr-0·5Mo-2W) and have produced significant improvements in creep rupture strength at temperatures up to 650°C compared with material given a conventional heat treatment. This has been achieved without any loss in ductility compared with conventional heat treatments. Test data for durations in excess of 40 000 h are presented. Modelling of microstructure evolution based on Monte Carlo simulations has shown important differences especially in the stability of grain boundary M23C6 and intragranular MX particles, between material with conventional and modified heat treatments. The model predictions are in good agreement with metallographic observations made on material before and after stress rupture testing. Continuum creep damage mechanics modelling based on the microstructural evolution has also been applied to predict creep life of Steel 92 and satisfactory agreement with creep rupture tests has been obtained.

History

School

  • Aeronautical, Automotive, Chemical and Materials Engineering

Department

  • Materials

Citation

YIN, Y. ... et al, 2008. Modelling and experimental studies of alternative heat treatments in Steel 92 to optimise long term stress rupture properties. Energy Materials, 3 (4), pp. 232-242

Publisher

© Maney Publishing & Institute of Materials, Minerals and Mining

Version

  • AM (Accepted Manuscript)

Publication date

2008

Notes

This article was published in the journal, Energy Materials [© Maney Publishing & The Institute of Materials, Minerals and Mining ]. It is also available at: www.maney.co.uk

ISSN

1748-9237

Language

  • en

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