Dynamic changes in slag properties during the reduction stage of the AOD process

Abstract

<div lang="en" class="abs"><p class="abs_header">Abstract</p><p>Argon-oxygen decarburization (AOD) is the main process for refining stainless steel. During the AOD process, the composition and properties of the slag undergo great changes owing to changes in composition and temperature. Decarburization slag contains large amounts of solid phases, particularly chromiumcontaining oxide phases and sometimes undissolved lime particles. During the reduction stage, the metallic oxides contained by the slag are reduced rapidly. However, there is a lack of information regarding the dynamic evolution of the slag composition and its physical properties during the reduction stage. To this end, a sampling trial was conducted to measure the dynamic changes in slag composition. To determine the phase structure and viscosity of the slag, computational thermodynamics calculations were carried out using the Thermo-Calc software. According to the results obtained using Thermo-Calc, the solid fraction of the slag dropped from 17 25 wt-% before the reduction stage to 0 4 wt-% after the reduction stage. Moreover, the decrease in solid fraction had a considerable effect on the effective viscosity of the slag. The solid fractions calculated with Thermo-Calc were found to be reasonably in line with those calculated with FactSage, but there were some discrepancies in the calculated viscosities. A comparison with previous computational studies on the phase composition of AOD slags revealed significant differences between the results obtained using different databases.</p></div>