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Abstract

The corrosion behaviour of two advanced Fe-based alloys, FeCrAlloy and MA 956, in both as-received and preoxidised conditions, was compared during exposure to H(2)-CO-H(2)O-H(2)S gas mixtures. The tests were performed at 600 C in three H(2)S-containing atmospheres for exposure periods up to 1000 h. Weight gain measurements, metallography, X-ray diffraction and SEM-EDS analysis of the scales were carried out on the corroded specimens. The results show that the alloys developed mainly Cr-based oxide scales in the lower H(2)S-containing gas mixture, whilst in the higher H(2)S-containing gaseous environments, both alloys suffered sulphidation attack. The presence of yttrium in the two alloys, either as a metallic element (in FeCrAlloy) or as an oxide dispersion (in MA 956), was found to influence the character of the Al(2)O(3) scales developed during pre-oxidation treatments, resulting in an improved resistance to sulphidation attack in all the environments investigated. The study highlighted some differences between the corrosion resistance of FeCrAlloy and MA 956 in the preoxidised form, resulting from changes in the physical properties of the Al(2)O(3) layers.

Additional information

Authors: SANTORELLI R L, CISE SpA, Segrate (IT);NORTON J F, JRC Petten (NL);BREGANI F, ENEL-CRTN, Milano (IT)
Bibliographic Reference: Article: Werkstoffe und Korrosion, Vol. 41 (1990) pp. 669-677
Record Number: 199110529 / Last updated on: 1994-12-02
Category: PUBLICATION
Original language: en
Available languages: en