Effect of Austenitising and Deformation Temperatures on Dynamic Recrystallisation in Nb-Ti Microalloyed Steel

An investigation into the influence of the reheat temperature and the austenite deformation temperature on Nb precipitation and recrystallisation kinetics was carried out for a steel containing 0.081C–0.021Ti–0.064Nb (wt. %). Thermo-mechanical processing was carried out using a Gleeble 3500 simulator. The austenite grain structure was correlated to the dispersive properties of Nb atom clustering and precipitation. Irrespective of the reheat temperature, deformation to 0.75 strain at 1075 °C produced a fully recrystallised austenitic microstructure. After deformation at 975 °C, only partial recrystallisation was observed in the samples reheated to the higher temperature, whereas samples reheated to the lower temperature were fully recrystallised. The influence of solute drag and particle pinning effects on the recrystallisation rate is discussed.