Abstract: Based on the wanger thermodynamic model, a computer program capable of calculating the equilibrium and paraequilibrium temperatures of austenite-ferrite transformation in multicomponent alloy steels with additions of Mn, Si, Ni, Cr, Mo, Cu, V, Nb, W and Co (total alloy < 7%) has been developed. The temperatures of austenite-ferrite transformation for a large amount of low alloy steels were calculated by the program. It is demonstrated that the predicted values compared favorable with the observed values.