Location of Repository

Development of Advanced Ferritic Steels for High Efficiency Power Generation Plant

By Guixiang Qin


E911 creep samples exposed to temperatures of 600˚C, 625˚C and 650˚C at differing stress levels were supplied by CORUS. The hardness of the gauge length that experienced both creep strain and temperature was found to be lower than that of the head where thermal softening only can be assumed. The changes in the morphology and size of precipitates were observed qualitatively by optical microscopy and Scanning Electron Microscopy. A creep fracture mechanism map of E911 steel was constructed with two modes of creep (transgranular and intergranular ). A fitted ellipse shape was used to characterise the irregular block shape by Electron Backscattered Diffraction (EBSD). It showed that the width of the block inside a prior austenite grain increases more rapidly in the gauge length than in the head; subgrain growth was also observed by EBSD. Transmission Electron Microscopy studies indicate that at 600°C E911 steel can reach up to 75647 hours creep rupture life (108MPa), which is due to the relatively small size of M23C6, Laves and M2X phases. However, Z phase precipitation results in a drop in creep resistance owing to the dissolution of fine MX phase and the transformation of M2X phase. At 625°C and 650°C, the creep rupture life decreases owing to the coarsening of Laves, M23C6 and M2X phases. \ud Four experimental steel casts were prepared with varying levels of Ni and Cr to investigate the effect of these elements on Z phase formation. After 10,000 hours exposure, there was little evidence of Z phase in the samples studied and therefore it is difficult to draw definitive conclusions about the role of Ni or Cr in promoting Z phase formation. It is possible that the casts studied here will allow better conclusions to be drawn after exposing the samples to longer durations

Topics: E911, Creep, SEM, TEM, EBSD, Z phase
Publisher: University of Leicester
Year: 2009
OAI identifier: oai:lra.le.ac.uk:2381/9944

Suggested articles



  1. (2006). 9-12% Cr Steels Microstructural Stability and Development Potentials,
  2. (1952). A Time-Temperature Relationship for Rupture and Creep Stresses, Trans.
  3. (2000). Advanced (700˚C) pulverised fuel power plant, in:
  4. Advanced high chromium ferritic steels for boiler components operating at high temperature,
  5. (2007). Aging coal-fired power plant becomes clean and efficient, in:
  6. (2006). An EFTEM study on Z phase Nucleation in Martensitic Chromium Steels, doi
  7. (2004). An Introduction to Materials Engineering and doi
  8. (2007). Application of electron backscatter diffraction to the study of phase transformations, doi
  9. (2008). Article Number:
  10. Basics explanation of creep processes,
  11. (1999). Boron distribution in 9-12% Cr steels, doi
  12. (2007). Boron in High Chromium Steels for USC Steam Power Plants, doi
  13. (2003). Brush seals in steam turbine power plant, In: A doi
  14. (2001). Cawley (Eds),
  15. (2001). Compositional changes in minor phases present in 12CrMoVNb steels during thermal exposure at 550 and 600°C, in : A.Strang , doi
  16. Creep resistant 9-12% Cr steels-long-term testing, microstructure stability and development potentials,
  17. (2004). Creep strength and ductility of 9-12% Cr steels, doi
  18. (1982). Deformation mechanism maps: the plasticity and creep of metals and ceramics,
  19. (2007). Effect of Boron on Creep Deformation Behaviour of 9Cr Steel for USC Boilers at 650°C, in: doi
  20. Efficient steam turbine technology for fossil fuel power plants in economically and ecologically driven markets,
  21. (2000). Electron backscattering diffraction study of acicular ferrite, bainite, and martensite steel microstructures, doi
  22. (2006). Electron diffraction studies on (Nb,V)CrN particles in 12CrMoVNbN steels,
  23. (2001). Electron Microscopy and Analysis, Third Edition , Published by Taylor
  24. Energy Dispersive X-ray Microanalysis for the TEM Explained, doi
  25. (1989). Engineering materials 1, An introduction to their properties and applications, doi
  26. (1998). Engineering materials 2, Butterworth-Heinemann press,
  27. (2007). Evaluation of microstructural parameters in 9-12% Cr-steels, doi
  28. (2001). Evaluation of particle size distribution of precipitates in a 9% Cr steel using EFTEM, doi
  29. (2006). Evaluation of the materials technology required for a 760˚C power steam boiler,
  30. (2007). Fireside issues in advanced power generation systems, In: doi
  31. (1994). Improving the elevated temperature strength of steel 91 (9%CrMoNbVN), in: Materials for Advanced Power Engineering, Liege: doi
  32. (1971). Interpretation of Electron Diffraction Patterns, doi
  33. (1990). Introduction to crystallography, doi
  34. (1956). Iron Steel Inst,
  35. Lattice structure of Z phase,
  36. Long-term stability of 9-12% Cr steels- Current understanding and future perspectives,
  37. (2003). Magnetic Detection of Microstructural Change in Power Plant Steels,
  38. (1999). Martensite in steel: Strength and structure. doi
  39. (1971). Martensite transformation, doi
  40. (2006). Materials challenges in CO2 capture and storage, doi
  41. (2003). Materials for Advanced Steam Power Plants: The European COST522 Action, in: A
  42. Materials specimen preparation for transmission electron microscopy, doi
  43. (2000). Mechanical behaviour of materials, second edition,
  44. (2006). Metallography and alloy design in the COST 536 action,
  45. (1975). Microscopy of materials, doi
  46. Microstructural analysis on a creep resistant 9- doi
  47. (2007). Microstructural modelling and rupture properties, in:
  48. (2004). Microstructural parameters and flow stress in Al-0.13% Mg deformed by ECAE processing, doi
  49. (2002). Microstructure Evolution in High Strength Steel for Power Plant Application: Microscopy and Modelling,
  50. (1994). Microstructure stability of 12CrMoVNb power plant steels, PhD Thesis,
  51. (1998). Model 656, User‟s Guide, Gatan, Inc. Revision 2,
  52. (2006). On the roles of M2X and Z-phase in tempered martensitic 9-12% Cr steels,
  53. (1998). part I,
  54. (2008). Phase evolution in P92 and E911 weld metals during ageing, doi
  55. (1951). PhD Thesis,
  56. (2006). Precipitation Behaviour of Z phase After Longterm Creep in High Chromium Heat Resistant Steels, doi
  57. (2005). Precipitation behaviour of Z phase during ageing and creep in 9-12% Cr ferritic heat resistant steels, in: International workshop on performance and requirements of structural materials for modern high efficient power plant,
  58. (1974). Principles and practise of electron microscope operation,
  59. (1996). Probing new markets,
  60. (2006). R.Ueji, N.Tsuji, Y.Minamino, doi
  61. (2003). Recent advances in creep-resistant steels for power plant applications, doi
  62. (2003). Recent advances in creep-resistant steels for power plant applications. doi
  63. (2001). Review - Grain and subgrain characterisation by electron backscatter diffraction, doi
  64. (2003). Scanning Electron Microscopy and X-Ray Microanalysis, doi
  65. (2001). Specimen preparation for electron backscatter diffraction -Part I: Metals,
  66. (2004). Stabilization wedges: solving the climate problem doi
  67. (1994). Steam turbine materials: high temperature forgings, in: Materials for Advanced Power Engineering, Liege: doi
  68. (1990). Steels heat treatment and processing principles, doi
  69. (1998). The commercial development and evaluation of E911: A strong 9% CrMoNbVWN steel for boiler tubes and headers, in: Advanced Heat Resistant Steels for Power Generation Applications,
  70. (1997). The development of 9%Cr Mo steels from steel 91 to E911, in: Microstructure of High Temperature Materials, Cambridge: The Institute of Materials,
  71. The evolution of the microstructure of the 9% chromium steels P92 during thermal ageing and creep exposure, doi
  72. (2003). The exploitation of advanced blading technologies for the design of highly efficient steam turbines, in: A
  73. (2007). The future materials needs of industrial gas turbines, in: doi
  74. (1997). The long-term creep rupture properties of 9-12%Cr steels, in: doi
  75. (1990). The Operation of Transmission and Scanning Electron Microscopes, doi
  76. (1985). Thin Foil Preparation for Electron Microscopy, Practical methods in electron microscopy, doi
  77. (1996). Transmission Electron Microscopy, Diffraction, part II, doi
  78. (1996). Transmission Electron Microscopy, Spectrometry, part IV, doi
  79. (2001). Worked Examples in the Geometry of Crystals, second edition, published electronically with permission from the Institute of Materials,
  80. (2003). X-ray and Image Analysis in Electron Microscopy,
  81. (2005). Yuichi Futamura, Toshihiro Tsuchiyama, Setsuo Takaki, doi
  82. (2006). Z-phase in 9-12% Cr Steels-Observations and Thermodynamic Modelling, doi

To submit an update or takedown request for this paper, please submit an Update/Correction/Removal Request.