Water vapour effect on cyclic oxidation of Fe-Cr alloys at 950°C

J. Zhang, Norinsan Kamil Othman, D. J. Young

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Model Fe-Cr alloys containing 9, 12, 17, 20, 25 or 30 wt. % Cr were subjected to repeated 1 hour cycles of exposure at 950°C to flowing gas mixtures of Ar-20O 2, Ar-20O 2-5H 2O and Ar-10H 2-5H 2O (all in volume %) for up to 240 cycles. The kinetics and metallographic cross-section analyses showed that in dry oxygen, alloys with ≥ 17 % Cr developed thin protective chromium-rich scales, while other low chromium alloys underwent fast breakaway oxidation. However, in Ar-20O 2- 5H 2O and Ar-10H 2 -5H 2O only the 25 and 30 Cr alloys were protected by a chromia scale, while alloys containing 20 Cr or less were subject to breakaway oxidation. Microstructural analysis revealed that multi-layered, thick iron-rich oxide scales grew during breakaway oxidation. An internal oxidation zone was clearly observed when the breakaway oxidation occurred in Ar-10H 2-5H 2O gas. Chromium concentration profile measurement using electron probe micro-analysis clearly showed a chromium depletion zone beneath the alloy surface when a protective chromia scale was formed. However, only a narrow depletion zone was developed when breakaway oxidation occurred. The effects of water vapour and chromium content on alloy oxidation are discussed in terms of oxide development and mass transfer processes during oxidation.

Original languageEnglish
Title of host publication18th International Corrosion Congress 2011
Pages806-814
Number of pages9
Volume2
Publication statusPublished - 2011
Event18th International Corrosion Congress 2011 - Perth, WA
Duration: 20 Nov 201124 Nov 2011

Other

Other18th International Corrosion Congress 2011
CityPerth, WA
Period20/11/1124/11/11

Fingerprint

Steam
Water vapor
water vapor
boundary layer separation
Oxidation
oxidation
Chromium
chromium
Oxides
Chromium Alloys
depletion
Internal oxidation
Chromium alloys
chromium alloys
Electron probe microanalysis
cycles
Gas mixtures
electron probes
microanalysis
iron oxides

Keywords

  • Breakaway oxidation
  • Cyclic oxidation
  • Fe-Cr
  • Water vapour

ASJC Scopus subject areas

  • Surfaces, Coatings and Films
  • Surfaces and Interfaces

Cite this

Zhang, J., Othman, N. K., & Young, D. J. (2011). Water vapour effect on cyclic oxidation of Fe-Cr alloys at 950°C. In 18th International Corrosion Congress 2011 (Vol. 2, pp. 806-814)

Water vapour effect on cyclic oxidation of Fe-Cr alloys at 950°C. / Zhang, J.; Othman, Norinsan Kamil; Young, D. J.

18th International Corrosion Congress 2011. Vol. 2 2011. p. 806-814.

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Zhang, J, Othman, NK & Young, DJ 2011, Water vapour effect on cyclic oxidation of Fe-Cr alloys at 950°C. in 18th International Corrosion Congress 2011. vol. 2, pp. 806-814, 18th International Corrosion Congress 2011, Perth, WA, 20/11/11.
Zhang J, Othman NK, Young DJ. Water vapour effect on cyclic oxidation of Fe-Cr alloys at 950°C. In 18th International Corrosion Congress 2011. Vol. 2. 2011. p. 806-814
Zhang, J. ; Othman, Norinsan Kamil ; Young, D. J. / Water vapour effect on cyclic oxidation of Fe-Cr alloys at 950°C. 18th International Corrosion Congress 2011. Vol. 2 2011. pp. 806-814
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N2 - Model Fe-Cr alloys containing 9, 12, 17, 20, 25 or 30 wt. % Cr were subjected to repeated 1 hour cycles of exposure at 950°C to flowing gas mixtures of Ar-20O 2, Ar-20O 2-5H 2O and Ar-10H 2-5H 2O (all in volume %) for up to 240 cycles. The kinetics and metallographic cross-section analyses showed that in dry oxygen, alloys with ≥ 17 % Cr developed thin protective chromium-rich scales, while other low chromium alloys underwent fast breakaway oxidation. However, in Ar-20O 2- 5H 2O and Ar-10H 2 -5H 2O only the 25 and 30 Cr alloys were protected by a chromia scale, while alloys containing 20 Cr or less were subject to breakaway oxidation. Microstructural analysis revealed that multi-layered, thick iron-rich oxide scales grew during breakaway oxidation. An internal oxidation zone was clearly observed when the breakaway oxidation occurred in Ar-10H 2-5H 2O gas. Chromium concentration profile measurement using electron probe micro-analysis clearly showed a chromium depletion zone beneath the alloy surface when a protective chromia scale was formed. However, only a narrow depletion zone was developed when breakaway oxidation occurred. The effects of water vapour and chromium content on alloy oxidation are discussed in terms of oxide development and mass transfer processes during oxidation.

AB - Model Fe-Cr alloys containing 9, 12, 17, 20, 25 or 30 wt. % Cr were subjected to repeated 1 hour cycles of exposure at 950°C to flowing gas mixtures of Ar-20O 2, Ar-20O 2-5H 2O and Ar-10H 2-5H 2O (all in volume %) for up to 240 cycles. The kinetics and metallographic cross-section analyses showed that in dry oxygen, alloys with ≥ 17 % Cr developed thin protective chromium-rich scales, while other low chromium alloys underwent fast breakaway oxidation. However, in Ar-20O 2- 5H 2O and Ar-10H 2 -5H 2O only the 25 and 30 Cr alloys were protected by a chromia scale, while alloys containing 20 Cr or less were subject to breakaway oxidation. Microstructural analysis revealed that multi-layered, thick iron-rich oxide scales grew during breakaway oxidation. An internal oxidation zone was clearly observed when the breakaway oxidation occurred in Ar-10H 2-5H 2O gas. Chromium concentration profile measurement using electron probe micro-analysis clearly showed a chromium depletion zone beneath the alloy surface when a protective chromia scale was formed. However, only a narrow depletion zone was developed when breakaway oxidation occurred. The effects of water vapour and chromium content on alloy oxidation are discussed in terms of oxide development and mass transfer processes during oxidation.

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