SIMULATION OF STEEL OXIDATION USING Mn, Si, Al IN THE COMPUTING ENVIRONMENT OF MathCAD USING DIFFERENT METHODS OF VISUALIZING CALCULATION RESULTS

Abstract

For modeling the deoxidation of traditional impurities (Mn, Si, Al), a method of using MathCAD is proposed, which includes various elements of calculation and visualization of the obtained results. It is shown by the method of a computational experiment that when the deoxidizer, R, is introduced, that is, an increase in [R], there is a nonlinear decrease in the concentration of dissolved oxygen [O] and the modulus of the numerical value (d[O])/dR. Analysis of the nature of the change in the deoxidation reaction rate, d/dR(d[O])/dR, indicates the existence of a concentration R at which a “break” in the dependence is observed (a decrease in the slope of the function d/(dR)(d[O])/ dR=f([R]), that is a pronounced decrease in the rate of change in the concentration [O]. In other words, starting from a certain value of [R], increasing the deoxidizer concentration is not effective. Optimal calculated concentrations of deoxidizers are proposed. The marginally necessary concentrations of deoxidizers [mass %], at which the rate of reduction of the content of [O] dissolved in steel is practically zero, are: [Mn] ≈ 0.85; [Si] ≈3.35; [Al]≈0.05. The technological concentration of [Al] can probably be reduced to ~0.015% (the “break-even” point), which theoretically allows [O] to be reduced to ~1.7·10-3 ppm at t 1600 °C. It is reasonable to assume that for deoxidation for steel using silicon, the optimal concentration is [Si] 0.5%. For manganese, this approach is not acceptable, for a weak deoxidizer, it is impractical to use the second “break” point, because at a concentration of [Mn] ~0.207%, [O] ~0.2% is observed in the calculation experiment, and if we apply the numerical value [Mn] ~0.85%, then the calculated value [O] ~0.05%, that is, four times less. The proposed modeling technique makes it possible to determine the maximum allowable concentration of dissolved in metal silicon [Si] used for its deoxidation, which corresponds to its concentration, at which a change in the direction of the binding reaction [O] is observed according to the principle of Le Chatelier – Brown. At [Si] 3.35 mass %, the rate of deoxidation is practically zero. A change (increase) in the concentration of [Si] leads to a disturbance of the equilibrium in the direction opposing the change made, namely: an increase in the concentration of the deoxidizer leads to an increase in the rate of increase in the concentration of oxygen.