High Temperature Tensile Properties and Related Microstructural Evolution in Grade 92 Steel
Ferritic-martensitic steels with good high temperature mechanical properties have many promising applications in fossil and nuclear power plants. In this work, a F92 steel was tensile tested from room to elevated temperatures (up to 700 °C). This material exhibited higher strength than traditional P92 steels. The reasons for the observed changes in mechanical properties were investigated by studying the microstructural characteristics in undeformed and deformed specimens using transmission electron microscopy. The microstructural evolution accelerated significantly under loading as temperature increased. For instance, the deformed microstructure at 600 °C showed early stages of M23C6 precipitate formation under loading. The M23C6 precipitates exhibited more coarsening tendency whereas the MX-type precipitates retained their size. As coarsening of M23C6 precipitates progressed at elevated temperatures, the strength gradually decreased as the solid solution strengthening deteriorated by removing W and Mo from the solid solution matrix.
KeywordsFerritic-martensitic steels Grade 92 steel 9Cr–2W steel Tensile testing TEM
The work was supported by the U.S. Department of Energy, Office of Nuclear Energy under DOE Idaho Operations Office Contract DE-AC07-051D14517, as part of an ATR Nuclear Science User Facility (ATR-NSUF) experiment. Authors would also like to thank Joanna Taylor, Jatu Burns and Dr. Yaqiao Wu at the Center for Advanced Energy Studies (CAES) in Idaho Falls, ID for their help.
- 17.L. Cipolla, H.K. Danilesen, D. Venditti, P.E. Di Nunzio, J. Hald, M.A.J. Somers, Conversion of MX nitrides to Z-phase in a martensitic 12% Cr steel. Acta Mater. 58, 669–679 (2010)Google Scholar
- 18.R.L. Higginson, C.M. Sellars, Worked Examples in Quantitative Metallography, 1st edn. (Maney Publishing, London, 2003)Google Scholar
- 19.R.W.K. Honeycombe, H.K. Bhadeshia, Steels: Microstructure and Properties, 2nd edn. (Edward Arnold, London, 1995)Google Scholar
- 23.R. Abbaschian, R.E. Reed-Hill, Physical Metallurgy Principles, 4th edn. (Van Nostrand, New Jersey, 2008)Google Scholar
- 26.C. Lacy, M. Gensamer, The tensile properties of alloyed ferrites. Trans. Am. Soc. Metals 32, 88–110 (1944)Google Scholar
- 30.L.M. Brown, R.K. Ham, Dislocation-particle interactions, in Strengthening Methods in Crystals, ed. by A. Kelly, R.B. Nicholson (Elsevier, Amsterdam, 1971), pp. 9–135Google Scholar
- 31.E. Nembach, Particle Strengthening of Metals and Alloys, 1st edn. (Wiley, New York, 1996)Google Scholar
- 32.H.J. Frost, M.F. Ashby, Deformation Mechanism Maps, 1st edn. (Pergamon Press, New York, 1982)Google Scholar
- 44.J. Hald, Metallurgy and creep properties of new 9-12% Cr steels. Steel Res. 12, 74–79 (2004)Google Scholar