Computer simulation of phase transformations in a complex alloyed steel

Purpose. Development and implementation of a computer model to analyze the effects of steel chemical composition of at the equilibrium temperature of the beginning and end of the ? ? α transformation, the position of the solvus lines of ferrite and austenite, as well as the temperature and carbon concentration corresponding to the eutectoid (pearlite). Methodology.Thermodynamic modelling based on conditions of the chemical potentials equality of α, ? and ? (cementite) phases determination. When determining the shape of the curves for the potential (geometric representation of Gibbs energy concentration dependence) ofeach phase used approach of Sundman-Ågren sublattice model with Redlich-Kister polynomial to calculate the excess energy of mixing. To determine the equations of common tangents to the curves of potentials used methods for numerical differentiation in combination with the method of least squares in order to find equal values of the slope and intercept. To implement calculations used written in C ++ module, which is a part of a software project for the simulation of phase transformations. Results. The computer model allows determining the phase transformation temperature of the steel and the equilibrium content of the carbon in phases at a predetermined temperature. Examples of the effect of Mn, Si, Ni, Cr and Mo on the shape of a quasi-binary polythermal section ofphase Fe-C with alloying elements diagrams near eutectoid (pearlite) transformation calculations are given. Originality. Using physically grounded modelling method a quantitative relationship between the composition of complex alloyed steel and the position of its critical points was shown. Practical value. Was build a computer model which using previously developed software, enables a high degree of reliability calculation of carbonitride phases formation in steels, in particular the conditions of excessive phase precipitation process, as well as gives information for adjusting the temperature of an effective thermal and/or thermo-mechanicalprocessing for specified composition steel.