Modeling and simulation of dissolution process of bulk carbide in Fe–1C–1.44Cr low-alloy steel

Abstract

Because of the complex morphology of bulk carbides in the core of as-cast bearing steel, their dissolution process is complicated to model, since it is difficult to rationally simplify the bulk carbides using a simple geometric shape. In this study, a metallographic image of an actual bulk carbide is transformed into a two-dimensional physical model. A dissolution model for such bulk carbides is established using thermodynamic and kinetic methods, where the diffusion coefficients for carbon and chromium in austenite and the solute concentrations at the phase interface are calculated assuming local equilibrium conditions. The calculation results from the model are compared with the experimental values, after the bearing steel was soaked at 1150 °C, 1175 °C and 1200 °C, the difference between the measured area of bulk carbides in the core and the model calculation results was 65 μm2, 12 μm2 and 30 μm2, respectively.