High temperature corrosion of cast heat resisting steels in CO+CO2 gas mixtures

Nan Xu (1) , Daniel Monceau (1) , David Young (1) , Jader Furtado (2)

1 UNSW - University of New South Wales [Sydney]
2 Air Liquide, Centre de Recherche Claude-Delorme, Paris-Saclay, France.

Two commercial variants of the cast heat resistant grade HP40Nb (Fe–25Cr–35Ni, Nb modified) were exposed to CO/CO2 gases at 982 and 1080°C in order to simulate exposure to the carbon and oxygen potentials realised in steam reformers under normal and overheated conditions. Both alloys developed external chromium-rich oxide scales, intradendritic silica precipitates and interdendritic oxide protrusions where primary, interdendritic carbides were oxidised in situ. Surprisingly, the lower silicon content alloy developed a more continuous internal silica layer, thereby slowing external scaling. Intradendritic oxidation was fast in both alloys, and is attributed to interfacial oxygen diffusion. Both alloys underwent rapid internal carburisation, indicating that their oxide scales failed to prevent carbon access to the underlying alloys under these reaction conditions.

Mots clés: Internal oxidation; Selective oxidation; Kinetic parameters; Carburisation

Domaines: Matériaux

Nan Xu, Daniel Monceau, David Young, Jader Furtado. High temperature corrosion of cast heat resisting steels in CO+CO2 gas mixtures. Corrosion Science, 2008, 50 (8), pp.2398-2406. ⟨10.1016/j.corsci.2008.06.001⟩. ⟨hal-02141696⟩