Sensitization and Self-healing in Austenitic Stainless Steel: Quantitative Prediction Considering Carbide Nucleation and Growth

The degree of sensitization in an austenitic stainless steel, has been measured using double loop electrochemical reactivation tests, and the measured values compared with predictions based on grain boundary chromium depletion characteristics obtained using the precipitation and diffusion modules of Thermo-Calc. In order to quantitatively predict Cr depletion, the precipitation of M23C6 carbides that are responsible for sensitization has been modelled for isothermal conditions by treating nucleation and growth separately. Based on a critical chromium concentration, a depletion parameter that predicts both sensitization and self-healing is given.