Influence of strain rate on the microstructure of a thermo-mechanically processed medium carbon microalloyed steel

The microstructure of a medium carbon microalloyed steel has been studied in the as-cast condition as well as after high temperature torsion deformation. The range of deformation parameters of the tests covered the conditions used in the forming process of a real part. The influence of thermomechanical treatment conditions (true strain, true strain rate and temperature) on the final austenite grain size has been studied. The evolution of the austenite grain size is analyzed under conditions of static and dynamic recrystallization. It was found that the strain rate can be as important as the strain to influence the final microstructure and therefore the mechanical properties of the final product.