Effects of sulfur pressure on the sulfidation behavior of 310 stainless steel

Abstract

High-temperature sulfidation behavior of 310 stainless steel was studied over the temperature range of 700–900°C above a pure sulfur pool with the sulfurvapor range of 10−4–10−1 atm. The corrosion kinetics followed the parabolic rate law in all cases. The corrosion rates increased with increasing temperature and sulfur pressure. The scales formed on 310 stainless steel were complex and multilayered. The outer scale consisted of iron sulfide (with dissolved Cr), (Fe, Ni)9S8 and chromium sulfides (Cr2S3 and Cr3S4 with dissolved Fe), while the inner layer was a heterophasic mixture of Cr2S3, Cr3S4, NiCr2S4, and Fe1−xS. Platinum markers were found to be located at the interface between the inner and outer scales, suggesting that the outer scale grew by the outward transport of cations (Fe, Ni, and Cr), and the inner scale grew by the inward transport of sulfur. The formation of Cr2S3, Cr3S4, and NiCr2S4 partly blocked the transport of iron through the inner scale, resulting in a reduction of the corrosion rates as compared with the results in the literature.