The effect of microstructure on the oxidation and carburisation of 9Cr-1Mo steel exposed to CO2

Coghlan, Lawrence; Yan, S.; Shin, Aya; Pearson, Jonathan; Jepson, Mark A.; Higginson, R.L.

doi:10.1016/j.corsci.2021.109720

Cited by 8 publications

(8 citation statements)

References 39 publications

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“…substrate will affect its oxidation characteristics and will lead to differences in the oxide morphology due to the difference in elemental segregation. This has been previously discussed by the authors [34]. These oxide differences will affect the pore size, with the larger carbides leading to larger pores within the substrate.…”

Section: Oxide Interfacementioning

confidence: 69%

“…Deeper into the oxide, from the outer magnetite layer, the oxide will have formed after longer periods of exposure with the newest forming new oxide being formed at the internal oxidation zone. Previous work has shown the carbide volume fraction and carbide size increases with exposure time [17,21,34]. The increasing carbide size and frequency in the…”

Section: Porosity Discussion and Mechanismmentioning

confidence: 90%

“…This series shows that with exposure time Cr segregates in increasing volumes towards grain boundaries and also larger more frequent intergranular carbides. At early exposure times, the Cr is dispersed relatively uniform throughout, with less grain boundary segregation, whereas the opposite is true for the sample exposed for 15,068 h. These changes in the elemental distributions will affect the oxidation characteristics of the steel, with the uneven elemental distributions remaining in the Cr-rich spinel [34].…”

Section: Porosity Discussion and Mechanismmentioning

confidence: 99%

“…This increasing carbide presence within the substrate changes both the oxidation and carburisation characteristics of the steel, both through increased carbon concentration and elemental segregation. This elemental segregation across the carburised substrate will lead to uneven elemental distributions within the Cr-rich spinel [17,19,20] which are thought to be linked with the morphology of the oxide scale, with previous work proposing that the Cr-rich oxide areas are inhibiting pore migration and coalescence [21].…”

Section: Introductionmentioning

confidence: 95%

“…Banding of pores within the oxide formed on 9Cr-1Mo steel has been observed on 9Cr-1Mo steels exposed to CO 2 [2,7,26] and steam [8,27], with porosity bands forming parallel to the substrate/oxide interface, thought to be linked with the prior substrate microstructure [20]. This banding has been previously attributed to elemental segregation of Cr and Fe in the Cr-rich spinel oxide, with the pores forming in Cr deficient regions unable to migrate through Cr-rich regions [21].…”

Section: Introductionmentioning

confidence: 96%

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Using a plasma FIB system to characterise the porosity through the oxide scale formed on 9Cr-1Mo steel exposed to CO2

et al. 2022

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Focused ion beam microscopy and scanning electron microscopy have been used to characterise the porosity of the oxide scale of an experimental 9Cr–1Mo steel sample exposed for 4580 h in a CO2-rich environment. The magnetite shows a high frequency of spherical pores (~ 1 µm3) with no interconnectivity. The Cr-rich spinel layer shows greater interconnectivity, but no single pore spans the total oxide scale. A mechanism for the formation of the different morphologies observed across the scale is proposed, linking porosity changes across the oxide scale to the carburisation and elemental segregation of Cr within the substrate. Graphical abstract

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Section: Oxide Interfacementioning

confidence: 69%

Section: Porosity Discussion and Mechanismmentioning

confidence: 90%

Section: Porosity Discussion and Mechanismmentioning

confidence: 99%