A new model for the prediction of chromium depletion near grain boundaries and corresponding sensitization in austenitic stainless steels

摘要

The problem of sensitization in austenitic stainless steels has received a lot of attention in research literature as it is a life-limiting process for such kinds of steels. Although a lot of experiments have been carried out by various researchers, there exist very few attempts to develop suitable predictive tools for this problem based on numerical methods. In this work, a model for the rate of formation of carbides near the grain boundary, which is a precursor to chromium depletion, has been proposed. This model along with the diffusion equation for chromium in the grain has been used to obtain chromium depletion profiles at various time and temperature conditions. The finite-difference method has been used to solve the above equations in the spherical co-ordinate system and the results of time–temperature-sensitization diagrams of four different types of alloys have been compared with those of experiments from the literature.