Comparison of TRIP steel microstructures after thermo-mechanical treatment with isothermal and anisothermal deformation steps

Abstract

The processing strategy of thin-walled hollow parts was verified in this work by physical-material modelling using C-Mn-Si transformation induced plasticity (TRIP) steel microalloyed with Niobium. The specimens were processed by a thermo-mechanical simulator to simulate real processing conditions. Different processing methods were applied to the specimens during subsequent cooling. The influence of intensive forming which was carried out during a continual decrease of temperature was compared with the influence of deformation steps applied at chosen temperatures during cooling. The effect of deformation parameters on ferrite development, grain refinement and phase distribution was investigated. Resulting microstructures were characterized with the use of light optical microscopy, transmission electron microscopy of extraction carbon replicas and a new method of confocal laser scanning microscopy.