EFFECT OF GRAIN REFINMENT ON MECHANICAL PROPERTIES OF MICROALLOYED STEELS

Abstract

The goal of the present work was to study the effect of grain size and strain rate on the mechanical properties of microalloyed steels. The range of the microstructures was developed and their mechanical properties were measured under quasi-static conditions. The influence of different thermomechanical parameters on grain refinement, and thus, on final mechanical behavior of these steels seems to be very important issue, because of their application as the materials with both high strength and ductility. There is a clear lack of understanding of the role of intermediate ultrafine microstructures on the mechanical response of structural steels, which is important as this is the refinement level most likely to be achieved under industrial processes. The main scope of this research includes the development of thermomechanical treatments to produce ultra fine-grained steels with enhanced properties. These materials will be developed for the application in many industries (e.g. automotive industry, shipbuilding), and in any commercial applications where very good properties and good-quality construction materials are of paramount importance. The results of this work will allow to systematically correlate the evolution of deformation microstructure and the deformation mechanisms operating in fine-grained materials during processing. This work will also be directed towards understanding the specific strengthening mechanisms by which the plastic deformation leads to a refined grain size.