Mechanism of breakaway oxidation of Fe–Cr and Fe–Cr–Ni alloys in dry and wet carbon dioxide

Thomas Gheno (1, 2) , Daniel Monceau (2) , David Young (1)

1 UNSW - University of New South Wales [Sydney]
2 CIRIMAT - Centre interuniversitaire de recherche et d'ingenierie des matériaux

Model Fe-Cr and Fe-Cr-Ni alloys were exposed to Ar-CO2 and Ar-CO2-H2O gas mixtures at 650 °C. While all alloys initially formed protective Cr2O3 scales, nucleation and growth of iron-rich oxide nodules resulted in some cases in breakaway oxidation. The conditions leading to departure from the protective stage are discussed in terms of Cr2O3 thermodynamic and kinetic stability. The morphological and compositional evolutions accompanying nodule development were examined. The influence of carbide precipitation on alloy chromium diffusion and the ability of the alloy to form and maintain Cr-rich oxide layers was investigated.

Mots clés: Steel; High temperature corrosion; Internal oxidation; Selective oxidation

Domaines: Matériaux

Thomas Gheno, Daniel Monceau, David Young. Mechanism of breakaway oxidation of Fe–Cr and Fe–Cr–Ni alloys in dry and wet carbon dioxide. Corrosion Science, 2012, ⟨10.1016/j.corsci.2012.07.024⟩. ⟨hal-02020028⟩