Interfacial Phenomena and Reaction Kinetics between High Al Molten Steel and CaO-SiO2-Type Flux

Abstract

To understand the reaction mechanism between high Mn-high Al steel and slag, the reaction experiment of Fe-Mn-Al melts with CaO-SiO2-type flux was carried out in MgO crucible at 1873 K. The evolution of the morphology of interface was inspected firstly, and then the global reaction kinetics was modeled in consideration of the effect of dynamic interfacial phenomena. The results show that in the reaction of Fe-5 mass % Al alloy with high SiO2 or low SiO2 protective slag, the strong chemical affinity between the metal and flux leads to strong spontaneous emulsification and attenuated with the progression of the reaction. Combined with the change of interfacial area caused by emulsification, it is found that the global reaction kinetics can be described satisfactorily by the mass transfer model of Al in liquid steel, and the determined mass transfer coefficient was about k[Al]=4.46×10−5 m/s. However, the emulsification phenomenon in the reaction of Fe-13%Mn-5%Al alloy with low SiO2 slag did not disappear with the reaction, which can be attributed to the decreasing of the interfacial tension with Mn addition and the accumulation of C on the interface. This reaction process can be modeled by assuming the mass transfer of SiO2 in the slag as the rate-controlling step with the estimated transfer coefficient of k(SiO2)=5.12×10−6 m/s.