In order to diminish the industrial pollution to maintain the sustainable development and to reduce the cost of the steel production, a unified technology combining plastic forming and heat treatment for some steel parts production is suggested. This article mainly concerns part theoretical foundation of such technology, i.e. the thermodynamic and kinetic models of the ferrite and pearlite transformations under external stress. Simulation of the ferrite fraction after continuous cooling under stress in a low-alloyed steel is presented. The effects of stresses on bainitic and martensitic transformations are also briefly introduced. The unified technology seems favorable to be realized in manufacturing practice.