Abstract
In this work the influence of temperature (in the range of 773-993 K) and steel chemical composition on changes in metal compositions of M₇C₃, M₂₃C₆, M₆C, and MC carbides was studied. Temperature dependencies of Fe, Cr, Mo, and V contents in carbides were calculated, by means of thermodynamic database program PD-pp. From the point of view of chemical composition, five-component Fe-Cr-Mo-V-C systems, corresponding to four Cr-Mo-V (Cr-Mo) low alloy steels, were analyzed. With respect to changes in phase equilibria, the temperature range 773-993 K was divided into three subranges. In each of them, the temperature dependencies of carbide metal compositions showed typical linear or quadratic course. It was found that the V/Mo ratio in bulk influences the metal composition of carbides systematically.

Key words
equilibrium phase, Hillert-Staffansson sublattice model, thermodynamic database program

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