Initial Oxidation of Fe-Cr Alloys at Different Temperatures and Atmospheric Conditions: A ReaxFF Molecular Dynamics Approach

Q Hu and ZY Lyu and LD Xing and C Gu and YP Bao, ISIJ INTERNATIONAL, 64, 1967-1975 (2024).

DOI: 10.2355/isijinternational.ISIJINT-2024-235

Oxidation behavior during the continuous casting process significantly impacts steel quality. This study investigated the oxidation process of iron-chromium (Fe-Cr) alloys at different temperatures and atmospheric conditions using the molecular dynamics method. Results indicated that during oxidation, Fe and Cr atoms lost electrons while O atoms gained electrons. The ratio of consumed O positively correlated with temperature and O concentration. Oxidation severity was higher at increased O concentrations and 1 373 K, with the most severe oxidation occurring at lower temperatures with higher O concentrations. The oxidation rate constant in wet O concentrations was lower compared with pure O, with a higher oxidation kinetic index, indicating that continuous casting billets in water- cooled conditions should have a limited duration. The initial oxidation kinetics of the Fe-Cr alloy surfaces are all manifested as the initial rapid oxidation, followed by the slow oxidation growth process Additionally, Mean-Squared Displacement (MSD) of Fe atoms is larger than that of Cr atoms and Cr oxidizes in the inner layer to form a dense oxide, it prevents Cr from continuing to oxidize and diffuse outward, thus generating Fe-rich products on the surface of Fe-Cr alloys.

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