The Role of Alloy Composition on the Steam Oxidation Resistance of 9-12%Cr Steels

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Three commercial martensitic steels have been oxidised in steam at 600 and 650 °C for times up to 10000 h. The partition of minor elements within the oxide scales has been determined. Silicon forms an additional oxide layer beneath the spinel. Chromium, molybdenum and tungsten concentrate in the spinel and manganese is present in both the spinel and magnetite. Several proposed mechanisms for steam oxidation have been examined to explain the observed effects of alloy composition. Modification of the oxide defect structure and oxidant gas penetration through microcracks were identified as the mechanisms most able to explain the influence of alloy composition.

Info:

Periodical:

Materials Science Forum (Volumes 522-523)

Edited by:

Shigeji Taniguchi, Toshio Maruyama, Masayuki Yoshiba, Nobuo Otsuka and Yuuzou Kawahara

Pages:

129-138

DOI:

10.4028/www.scientific.net/MSF.522-523.129

Citation:

S. Osgerby and A. T. Fry, "The Role of Alloy Composition on the Steam Oxidation Resistance of 9-12%Cr Steels", Materials Science Forum, Vols. 522-523, pp. 129-138, 2006

Online since:

August 2006

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$35.00

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[10] [20] [30] [40] 0 10 20 30 40 50 Cr Equivalent Specific Mass Change, mg cm -2 600 °C 1000 h 600 °C 3000 h 600 °C 5000 h 1000 h model 3000 h model 5000 h model.

[10] [20] [30] [40] 0 10 20 30 40 50 Cr Equivalent Specifit Mass Change, mg cm-2 650 °C 1000 h 650 °C 3000 h 650 °C 5000 h 1000 h model 3000 h model 5000 h model (a) (b) (c) (a) (b) (c) Figure 3 SEM images of oxide scales formed after exposure to steam atmosphere at 650 °C for 300 h (a) P92 (b) Alloy 122 (c) X19 (a) (b) Figure 4 Elemental distribution map of P92 exposed for 3000 h at 650 °C (a) oxygen (b) silicon Figure 5 Elemental distribution in alloys exposed to steam at 650 °C for 1000 h (a) P92 (b) Alloy 122 (c) X19.

DOI: 10.1038/119650a0

[1] [2] [3] [4] [5] 0 50 100 150 200 250 Distance from Surface, µµµµm Normalised Concentration of Element Cr Mn Mo W Magnetite/Spinel Interface Spinel/Alloy Interface.

[1] [2] [3] [4] [5] 0 20 40 60 80 100 120 Distance from Surface, µµµµm Normalised Concentration of Element Cr Mn Mo W Magnetite/Spinel Interface Spinel/Alloy Interface.

[1] [2] [3] [4] [5] 0 10 20 30 40 50 Distance from Surface, µµµµm Normalised Concentration of Element Cr Mn Mo Magnetite/Spinel Interface Spinel/Alloy Interface (a) (b) (c).

[1] [2] [3] [4] [5] 0 50 100 150 200 250 Distance from Surface, µµµµm Normalised Concentration of Element Cr Mn Mo W Magnetite/Spinel Interface Spinel/Alloy Interface.

[1] [2] [3] [4] [5] 0 20 40 60 80 100 120 Distance from Surface, µµµµm Normalised Concentration of Element Cr Mn Mo W Magnetite/Spinel Interface Spinel/Alloy Interface.

[1] [2] [3] [4] [5] 0 10 20 30 40 50 Distance from Surface, µµµµm Normalised Concentration of Element Cr Mn Mo Magnetite/Spinel Interface Spinel/Alloy Interface (a) (b) (c) Figure 6 Schematic representation of Dissociation Mechanism for Steam Oxidation I II III IV Fe3O4 Void M3O4 H2O H H2O Fe++ Fe++ H2 I II III IV Fe3O4 Void M3O4 H2O H H2O Fe++ Fe++ H2.

DOI: 10.1021/ja01331a009

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