Possibilities of theoretical determination of equilibrium phase chemical compositions in low alloy steels using available thermodynamic data

In this work the influence of temperature tin the range of 773-993 K) and s teel chemical composition on changes in metal compositions of M7C3, M23C6, M6C, and MC carbides was studied. Temperature dependencies of Fe,Cr, Mo, an d V contents in carbides were calculated, by means of thermodynamic databas e program PD-pp. From the point of view of chemical composition, five-compo nent 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 depend encies of carbide metal compositions showed typical linear or quadratic cou rse. It was found that the V/Mo ratio in bulk influences the metal composit ion of carbides systematically.