Evaluation of Sensitization and Self-Healing in Austenitic Stainless Steels Based on Simulations of Cr-Depleted Zones

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A simulation of the grain boundary precipitation of the Cr-rich carbide, M23C6, in austenitic stainless steels has been carried out using the DICTRA software package employing kinetic and thermodynamic databases. Our calculations reproduced the evolution of the Cr-depleted zone close to M23C6 carbide and the disappearance of the zone after a long annealing time. In addition, the calculated time-temperature-sensitization diagrams were in line with the experimental results of typical corrosion trends with annealing time. According to our results, despite the simple treatment used, a reasonable approximation for the simulations was to set the initial width of the austenite region from which the carbon was drawn as a sixth of the grain size. We also confirmed that the onset of sensitization for a steel with 0.1 mass%C shifted to shorter times and to higher temperatures compared with a steel with 0.06 mass%C.