A new predicting methodology for the time temperature transformation diagrams of medium carbon multicomponent alloy steels is proposed. Some critical transformation points used to model the time temperature transformation diagrams of multicomponent alloy steels are given as a function of alloy chemistry. It has been found that the bay between two C curves(pearlite and bainite) can be predicted correctly in terms of a precisely calculated B s temperature. The commercial application potential of this approach to the design of new multicomponent alloy steels is also discussed in detail