Decarburization Reaction in Ultra-low Carbon Iron Melt under Reduced Pressure

Abstract

The kinetics of the decarburization reaction with dissolved oxygen in a liquid iron in the ultraolow carbon concentration range under reduced pressure have been studied, using an induction furnace with a 20 kg melt. The results obtained are as follows:
(1) The decarburization reaction proceeds to less than 5 ppm of carbon, and the decarburization rate constant, K, decreases as the carbon content decreases.
(2) As the pressure in the chamber decreases, the decarburization rate increases with a carbon content of more than 10 ppm. On the other hand, the dependency of decarburization rate on the pressure in the chamber is small, with less than 10 ppm of carbon.
(3) The influence of the sulphur content on the decarburization rate is small with a carbon content of more than 10 ppm. The decarburization rates are not affected by the mass transfer of CO in the gas phase under experimental conditions. Thus, it is concluded that the decarburization rate is controlled by the mass transfer of carbon in liquid iron.
(4) The fact that the decarburization rate at a carbon content of more than 10 ppm is affected by the total pressure of the chamber has been explained by the change in interfacial area of the reaction between the gas and liquid phases resulting from CO boiling in the bulk melt.
(5) The decrease in the decarburization rate in t he ultra-low carbon concentration range in RH is also caused by the decrease in interfacial area of the reaction between the gas and liquid phases.