Oxidation of iron at 600 degree C - experiments and simulations

• Published in: Materials and corrosion Vol. 68; no. 2; pp. 133 - 142
• Main Authors: Larsson, H, Jonsson, T, Naraghi, R, Gong, Y, Reed, R C, Aagren, J
• Format: Journal Article
• Language: English
• Published: 01-02-2017
• Subjects: Computer simulation; Homogenizing; Iron; Mathematical models; Oxidation; Oxides; Phase transformations; Simulation
• DOI: 10.1002/maco.201508781
• EISSN: 1521-4176
• ISSN: 0947-5117

Pure iron has been oxidized at 600 degree C and 1bar in dry O sub(2) (oxygen partial pressure 0.05, bal. N sub(2)) and the mass gain as well as the thicknesses of the individual oxide phases have been measured. The oxidation process has been simulated using a modified version of the homogenization model as implemented in Dictra; this has helped to rationalize the kinetics of oxide scale formation and in particular the evolution of the hematite (Fe sub(2)O sub(3)), magnetite (Fe sub(3)O sub(4)), and wustite (FeO) which form. Independently assessed thermodynamic and kinetic Calphad databases are needed for the calculations; details of these are given. Reasonable agreement between simulation results and experimental data is obtained, though it is concluded that the large influence of grain boundary diffusion on the oxidation rate needs further consideration. As a first step toward multicomponent simulations of oxidation, simulations of oxidation of pure iron has been performed. The simulations were performed using a modified version of the homogenization model as implemented in Dictra using Calphad databases. A reasonable agreement with experimental data has been obtained.