High-temperature corrosion and carburization behaviour of austenitic stainless steels in impurity-added CO₂ environments

The corrosion and carburization behaviour of four austenitic stainless steels were evaluated in CO₂ and CO₂+impurities (CH₄, CO and O₂) at 600 °C. Exposure to CO₂, CO₂+CH₄, and CO₂+CO environments showed poor corrosion resistance, especially in 316 grades with the spallation of Cr₂O₃ layer and breakaway corrosion. Conversely, materials showed improved corrosion resistance in CO₂+O₂ environment with thin Cr₂O₃ layer. TEM analysis of 316LN revealed carbon-accumulated layer at the Cr₂O₃–matrix interface for highly corrosive environments. The degradation of Cr₂O₃ adherency is correlated with the carbon-accumulated layer, resulting from the high carbon activity in CO₂, CO₂+CH₄, and CO₂+CO environments.