Experimental Study on Decarburization and Chromium Retention in Stainless Steel Smelting with CO2 as Alternative to N2

Abstract

Reusing CO2 as a secondary resource in the steel industry is one of the research hotspots in recent years. Herein, O2–N2 and O2–CO2 are injected into Fe–C–Cr melt at 1823 K to study the effect of CO2 (as an alternative to N2) on decarburization and chromium loss in the argon–oxygen decarburization (AOD) stainless steel smelting process. The results show a higher decarburization rate and lower chromium loss with O2–CO2 injection compared with O2–N2 injection. CO2 injection helps oxidatively remove a part of carbon (C) in the melt. Simultaneously, the increase in CO partial pressure reduces the loss of Cr by CO2 oxidation to a measurable extent. In the middle–late stage of smelting, the corresponding content of C and Cr is relatively consistent with the trend of thermodynamic analysis. From the view of kinetics, CO2 injection increases the gas–metal interface area to improve the Cr formation rate in the melt, improving decarburization and chromium retention with the substitution of CO2 for N2. The research results herein provide a new direction for the development of the AOD process in the future and put forward a way of CO2 resource utilization.