MODELING LOW-TEMPERATURE SENSITIZATION OF AUSTENITIC STAINLESS-STEELS

Sensitization is the enhanced susceptibility of stainless steels to intergranular corrosion following heat treatment in the temperature range 550-850 degree C. In this paper, the earlier model of sensitization for 304 SS has been extended to 316 SS and to lower temperatures. The model predictions agree qualitatively with preliminary experimental results. The model predictions are conservative in that shorter times are predicted for sensitization to occur. Cr need not diffuse over large distances at low temperatures since M//2//3C//6 has only 20-30 wt. % Cr. Segregation of elements like S, P, N etc. can reduce the effective area over which pipe diffusion can occur and retard the sensitization kinetics.