Quantitative research on effects of Nb on hot deformation behaviors of high-Nb microalloyed steels

► The amount of Nb in solution and/or in precipitates was determined. ► The Nb cannot be completely dissolved during the reheating process. ► The precipitates cannot effect on dynamic recrystallization. ► The Qdef presents a perfect linear correlation with the amount of Nb in solution. ► Each addition of 1 wt% Nb in solution adds 1599.9 ± 137.7 kJ/mol to Qdef.