MODELING OF THE INFLUENCE OF THERMOMECHANICAL PROCESSING OF NB-MICROALLOYED STEEL ON THE RESULTING MECHANICAL-PROPERTIES

Two-stage compression tests were performed at various temperatures and reductions. The influence of finish deformation temperature in the ra nge of 650-820 degrees C and strain on microstructure and final mechan ical properties of Nb steel is investigated. Starting from detailed si mulation of microstructure development, i.e. recrystallization, precip itation and grain growth kinetics, the material behaviour was modelled . An empirical model of yield strength, developed in previous work, is employed to predict mechanical properties of microalloying steel duri ng hot deformation above and below the gamma-alpha transformation temp erature. The comparison of simulated and measured results shows that t he real thermomechanical behaviour as well as the microstructure devel opment of Nb-steel has been correctly implemented. The results provide d by both finite element analyses and microstructure modelling were co mpared with earlier similar investigations of C-Mn steel. (C) 1998 Els evier Science S.A. All rights reserved.