Use of the computer simulation to predict mechanical properties of C-Mn steel, after thermomechanical processing

The objective of the paper is to demonstrate the ability of a computer simulation to analyse the development of microstructure and finally to the predict mechanical properties of C-Mn steels. The microstructure of ferrite is the main parameter which controls the mechanical properties of steels after hot deformation. This microstructure depends on the grain size and morphology of austenite just before the transformation. However, when the last deformation takes place below the gamma-alpha transformation temperature, the mechanisms connected with substructure and dislocation forest becomes a significant part of the strengthening process. The microstructural model makes it possible to separate the relative contributions of solid solution, ferrite microstructure, substructure and dislocation strengthening. The change in microstructure at lower temperatures requires an improvement in the model which will allow to account for the substructure and dislocation density. In the present work hot deformation conditions were simulated using Finite Element Method. The investigation was focused on the case when the last deformation takes place in the two phase or ferrite region. The two stage constant strain rate compression tests were conducted, in continuous cooling condition, at the temperature range 1050 - 650 degrees C. The material after deformation was investigated to obtain the microstructure and verify the model of substructure and dislocation strengthening mechanisms. The experimental results were used to validate and improve the empirical equations that were employed to the general model. The computer simulation suggested in the work can be used to predict mechanical properties, including all the events that occur under industrial processing conditions which cannot be reproduced in the laboratory.