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 600oC. 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.