Abstract
Creep strength degradation of Creep Strength Enhanced Ferritic (CSEF) steels was investigated, focusing on microstructural degradation. The creep strength of ASME Gr.91 steel remarkably decreased in the long-term at 600oC and 650oC. If the data in the long-term are selected for regression analysis, we can accurately evaluate long-term creep strength. The data under applied stresses larger than proportional limit stress should be omitted for the analysis. Creep deformation under a stress lower than proportional limit stress is strongly affected by microstructural changes due to diffusion. After long-term creep exposure at 600oC, the martensitic lath structure was collapsed by recovery and coarsening of precipitates occurred. The recovery of lath structure preferentially occurred around prior austenite grain boundaries. The Z-phase particles nucleated around prior austenite grain boundaries during creep exposure, consuming fine MX particles that were main strengthener.
This is a preview of subscription content, log in via an institution.
Buying options
Tax calculation will be finalised at checkout
Purchases are for personal use only
Learn about institutional subscriptionsPreview
Unable to display preview. Download preview PDF.
References
Masuyama F. History of Power Plants and Progress in Heat Resistant Steels. ISIJ Int., 41, 612–625 (2001)
Onizawa T, Wakai T, Ando M and Aoto K: Proc. Creep and Fracture in High Temperature Components—Design and Life Assessment Issues, ed. by I. A. Shibli et al., DEStech Publications, Inc., Lancaster, USA, (2005), 130.
Tanigawa H et al. Technical issues of reduced activation ferritic/martensitic steels for fabrication of ITER test blanket modules. Fusion Engineering and Design 83, 1471–1476 (2008)
Kimura K. Assessment of long-term creep strength and review of allowable stress of high Cr ferritic creep resistant steels. Proc. PVP2005, 2005 ASME Pressure Vessels and Piping Division Conference, Denver, Colorado USA; July 17–21 2005.
Kimura K. Creep strength assessment and review of allowable tensile stress of creep strength enhanced ferritic steels in Japan. Proc. PVP2006/ICPVT- 11, 2006 ASME Pressure Vessels and Piping Division Conference, Vancouver, BC, Canada; July23-27 2006.
Kushima H, Kimura K, Abe F. Degradation of Mod.9Cr 1Mo Steel during long-term creep deformation. Tetsu-to-Hagane 85, 841–847 (1999)
Maruyama K, Sawada K and Koike J. Strengthening mechanisms of creep resistant tempered martensitic steel. ISIJ Int., 41 641–653 (2001)
Hald J. Metallography and alloy design in the COST 536 action. In: Lecomte- Beckers J, et al, editor. 8th Liege Conf. on Materials for Advanced Power Engineering. ulich:Forschungszentrum, Julich GmbH; 2006.
Sawada K, Kushima H, Kimura K, Tabuchi M. TTP diagrams of Z phase in 9-12%Cr heat resistant steels. ISIJ Int 47, 733–739 (2007).
Cipolla L, Danielsen H.K, Venditti D, Nunzio P.E.Di, Hald J and Somers M.A.J. Conversion of MX nitrides to Z-phase in a martensitic 12% Cr steel. Acta Mater., 58, 669–679 (2010)
Author information
Authors and Affiliations
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2012 Springer-Verlag Berlin Heidelberg
About this chapter
Cite this chapter
Sawada, K., Tabuchi, M., Kimura, K. (2012). Degradation Mechanism of Creep Strength Enhanced Ferritic Steels for Power Plants. In: Böllinghaus, T., Lexow, J., Kishi, T., Kitagawa, M. (eds) Materials Challenges and Testing for Supply of Energy and Resources. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-23348-7_4
Download citation
DOI: https://doi.org/10.1007/978-3-642-23348-7_4
Published:
Publisher Name: Springer, Berlin, Heidelberg
Print ISBN: 978-3-642-23347-0
Online ISBN: 978-3-642-23348-7
eBook Packages: Chemistry and Materials ScienceChemistry and Material Science (R0)