Mathematical model for decarburization of ultra-low carbon steel during RH treatment

Abstract

A mathematical model was established to investigate the decarburization behaviour of ultra-low carbon steel during Ruhrstahl-Heraeus (RH) refining process. In this model, it was assumed that the decarburization reactions occur at four sites: Ar bubble surface, bath surface, bulk steel and splash droplet surface. The effect of Ar bubble behaviour and splash droplet behaviour on decarburization rate was taken into consideration specifically. The calculated results are basically consistent with the industrial experimental observations. Carbon concentration was mainly eliminated at bath surface at early stage of RH treatment, and was mostly removed in bulk steel at middle stage, and was removed at splash droplet surface in the final stage. The decarburization rate at different sites and its contribution to total decarburization value were evaluated in detail. The decarburization rate during RH treatment could be effectively improved by accelerating the drop of vacuum pressure at early stage. Appropriate increasing Ar gas flow rate was beneficial to deep decarburization by increasing the reaction area of droplet surface and bath surface.

Modeling Fluid Flow and Carbon Removal in the Ruhrstahl–Heraeus Reactor: Considering the Pumping Process

“…Decarburization can take place at the Ar bubble surface owing to the low CO partial pressure in a bubble . This decarburization mechanism is similar to that of decarburization at the bath surface, and the mass transfer of dissolved C to the bubble surface is also suggested as the rate-determining step.…”

Physical and Numerical Modeling of the Impeller Construction Impact on the Aluminum Degassing Process

“…Zhang [ 26 ] proposed a model taking into account the temperature difference between gas and alloy (metal). where T g is the gas temperature at the entry point.…”

Modeling of the Melting of Aluminum Particles during the RH Refining Process

“…Figure 2 shows the temperature profile and the melting process of the aluminum particle. Based on the heat transfer between the aluminum particle and the molten steel, the steel shell is frozen around the aluminum particle, and the radius of the particle is given by Equation (1) [4,23].…”

“…Some variables, including the melting time, the trajectory length, and the melting position, are recorded during the calculation using user-defined functions. Further, the lifetime of the steel shell t Al is derived by Equations (3) and (5) from references [4,23] and given by Equation (9). where h is the heat transfer coefficient, J/m 2 ·s·K.…”