Prediction of Carbide Precipitation Using Partial Equilibrium Approximation in Fe–C–V–W–Cr–Mo High Speed Steels

抄録

In Fe–C–V–W–Cr–Mo high speed steels, the nature of carbides during the solidification are discussed as a function of C, V and W content by the help of Partial Equilibrium (PE) approximation and thermodynamic calculations. The results show that the solidification path and carbide precipitation can be reasonably predicted by the Partial Equilibrium approximation for cooling rate lower than 10–13 K min^–1. From the viewpoint of hardness control by carbides, it is found that among the main carbides MC, M₆C and M₇C₃, the increase of C favours the formation of MC, M₇C₃ but decreases the hardness of M₇C₃ by increasing the Fe content in it. Meanwhile, the increase of V only increases the amount of MC and V content therein, and the increase of W largely increases the amount of M₆C and W content in it. As a result, the addition of V and W improves the hardness of MC and M₆C carbides.