Decomposition kinetics of supercooled austenite in porous powder steel

Resumo

To determine the best heat treatment of steel, thermokinetic diagrams of austenite decomposition are required. Experimental determination of those diagrams is extremely difficult. In the present work, a model of the phase transitions is proposed; the model takes account of the structure of powder steel. A method is developed for computer experiments with steel cooling. The proposed model permits the determination of the kinetic parameters of austenite decomposition on the basis of isothermal diagrams for two values of the steel porosity. By that means, the transformation kinetics in this steel may be predicted for other values of the porosity, both in isothermal conditions and in continuous cooling. The model is verified for У8 and ПК80 steel with different porosity, by means of published experimental data.