Corrosion of Fe-25Cr-20Ni-0.40C alloy: an experimental and computational study

C. LANZ; A. JUAN; G. BRIZUELA; S. SIMONETTI

Conferencia; 2015 International Conference on Modelling, Simulation and Applied Mathematics; 2015

The investigation combines microstructural characterization analyses and atomistic modeling to elucidate themechanism of carburization embrittlement of an iron-nickelchromium alloy exposed to high temperature. It was studied an austenitic Fe-25Cr-20Ni-0.40C stainless steel obtained of the tubes of the industrial cracking furnace after 25,000 h of service at 900-1200 ºC. The service-exposed material presented bigger carbides in the austenitic matrix comparing with the as-cast material, cavities between the grains and micro fissures in grain edges, indicating that the material present damage by creep. The theoretical calculations help us to interpret the changes in the alloy electronic structure and the chemical bonding. The atomic orbital occupations of the metallic bonds are affected during carburization. The strengths of the, Cr-Ni, Fe-Cr, Fe-Ni and Ni-Ni bonds nearest neighbors to the carbon atoms are the most affected. The metallic bond weakening is mainly a consequence of the new C-Ni, C-Fe and C-Cr interactions formed aftercarburization phenomena.