Computer-based simulation of high-temperature corrosion phenomena

The aim of this paper is to introduce a computer simulation tool, which is designed for prediction of service-life of components operating under corrosive conditions such as carburization, oxidation and nitridation at high-temperature. Different classes of materials (low-Cr ferritic steels, austenitic steels and Ni-base superalloys) were exposed at temperatures between 550 degrees C and 1000 degrees C to different corrosive atmospheres (carburizing, oxidizing and nitriding). The tool for the prediction of internal/inwards corrosion processes at high-temperatures makes use of the numerical finite-difference technique to treat diffusional kinetics on the one hand and the concept of local equilibrium thermodynamics on the other hand. For this purpose, a link has been established between the numerical environment of MATLAB and the thermodynamic library ChemApp. Using this new tool, the kinetics of nitridation, oxidation and carburization processes were predicted numerically taking the material's microstructure into consideration by distinguishing between precipitation along the grain boundaries and within the grain interior. Excellent agreement between experimental observations and simulation results revealed the high potential of the computer modeling for application to complex corrosion processes.