Corrosion of S32205 Duplex Stainless Steel

The corrosion behavior of S32205 duplex stainless steel was evaluated in pulping liquors obtained from a Kraft pulp mill and various sulfate- and chloride-containing media to assess its suitability for industrial applications in the pulp and paper industry. Electrochemical testing included corrosion potential measurements and cyclic polarization, which were used to evaluate the stainless steel’s resistance to uniform and localized corrosion. Scanning electron microscopy and energy-dispersive x-ray spectroscopy were used in the post-exposure surface analysis. The results showed that S32205 exhibits varying degrees of corrosion resistance based on the medium. In chloride-containing environments, pitting corrosion was observed, while sulfate-containing media induced mostly uniform corrosion. The most corrosive media was white liquor, attributed to its high sodium hydroxide content, whereas chlorine dioxide was the least corrosive due to its oxidizing characteristic. Additionally, temperature was a factor influencing corrosion rates, with increasing temperatures leading to accelerated passive film breakdown. While S32205 shows promise in chloride-containing environments, it suffers extensive corrosion rates in pulp liquors. These findings advance material selection strategies for improving equipment longevity in pulp and paper mills.