Modeling of Microstructure and Mechanical Properties of Hot Rolled Steels

An integral mathematical physically based model is developed for prediction of the microstructure and mechanical properties of steels processed in accordance with a given hot deformation and accelerated cooling regimes. The model predicts austenite microstructure evolution under hot deformation, as well as its transformation during subsequent cooling with account of formation of ferrite, pearlite, bainite and martensite. Structure-property relationships are developed using an extensive experimental database chemical composition - microstructure - mechanical properties obtained for 10 steel grades. Austenite transformation depending on grain size, cooling rate and preliminary plastic deformation was investigated with the help of Gleeble 3800 system to obtain a set of practically important morphologically different microstructures for each steel grade. A quantitative analysis of the microstructures was performed using optical and scanning electron microscopy (EBSD-method). Investigation of the mechanical properties of steels with wide spectrum of obtained microstructures was carried out on the double-samples processed using Gleeble 3800. The predicted microstructure parameters for investigated steels obtained using the developed model, as well as their mechanical properties, are in good agreement with the experimental data.