The effect of TMCP parameters on the microstructure and mechanical properties of Ti-Nb microalloyed steel

The aim of this work was to study the influence of thermomechanical controlled process parameters on the refinement of microstructure during processing as well as the final microstructure and mechanical properties of Nb microalloyed steel. The steel was investigated and thermo-mechanical controlled process simulations were carried out using the material testing system 810. The effect of deformation sequences with constant finish rolling temperature and accelerated controlled cooling rate were studied with regard to strength and microstructure of heavy plate. The optimized thermo-mechanical controlled process parameters will be discussed in relation to the microstructure and precipitate evolution, as well as the mechanical properties of high-strength steel, microalloyed with Nb and Ti. The best results for strength were obtained for accelerated controlled cooling rates >5 degrees C s(-1) in the present cases where the finishing temperature was 850 degrees C, for both light and heavy reductions.