Thermomechanical treatments of new medium carbon microalloyed bainitic steels. Microstructural and mechanical

摘要

This paper forms part of a work made in newmedium carbon bainitic microalloyed steels, Differentexperimental heats of these steels have been prepared in avacuum furnace. The main microalloying elements have beenV, Ti and B. In some of them Mo was also added. The workhas comprised the study of different properties, such as:austenitic grain growth evolution with temperature,continuous cooling transformation diagrams, hot ductility,forging process of automotive components simulation, realforging of a component, and the influence of hot forgingparameters on the structure and properties of this real forgedcritical automotive component (a wheel hub). The testsperformed to obtain the austenitic grain growth and the CCTdiagrams on one hand, and the mechanical properties after hotforging on the other, were carried out with the aid ofdilatometry and torsion technics respectively. The presentpaper will be focused on determining the mechanicalproperties of this family of steels with and without boron.These property values are compared with the ones obtainedwith ferritic-pearlitic microalloyed steels and quenched andtempered conventional steels. Finally, we discuss the resultsobtained by hot torsion simulation and the ones obtained fromthe components forged in the forging shop.