The corrosion behaviors of Fe-Cr alloys have been examined at 700 ℃ in reducing atmospheres containing contant HCl and two differnernt levels of H2S. An increase of the H2S level in the gas mixture produced an accelerated corrosion for all Fe-Cr alloys, particularly inducing the degradation of chromia formed on Fe-18Cr alloy as a consequence of the formation of sulfides and chlorides in the scales. An increase of the Cr content decreased the corrosion rate in the two gas mixtures. The equilibrium partial pressures of chlorine, oxygen and sulfur in the mixed gases were calculated to estimate the possible reactions between the alloy components and the multi-reactants, and their corrosion mechanisms were also interpreted.
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