A Thermodynamic and Kinetic‐Based Argon Oxygen Decarburization Process Model and Validation with Plant Data

Abstract

Argon oxygen decarburization (AOD) is one of the most dynamic and complex processes in stainless steel production. Along with a lot of metallic additions, oxygen (O2), argon (Ar), or nitrogen (N2) gas is blown into the reactor to produce complex stainless‐steel grades. Typically, a hit‐and‐trial method approach is followed in the plant to optimize the critical process parameters for producing any new grades or optimizing the existing ones. In this regard, a mathematical model of the process coupled with robust thermodynamic databases is adopted to optimize the process. As discussed in the manuscript, most of the previous models explain the decarburization patterns by assuming a critical carbon (C) content to justify the change in decarburization rate from surface oxidation due to high O2 flow rates at high C levels to liquid phase mass transfer of C at low C levels. In the current study, decarburization patterns are described without any assumption of critical C content. The modeling results are validated against the plant data for a standard 316L grade in a 150 ton AOD converter. Next, the model parameters are implemented as it is for grades 439 and 321 and the AOD model is used as a predictive tool for these grades.