Hot deformation and recrystallisation of low Mn steels with different Ti/N ratio

The effects of small titanium and nitrogen additions on the mechanical properties andmicrostructural characteristics of four different low carbon, low manganese steels have beenstudied using a Gleeble thermomechanical simulator and TEM investigations. The Ti/N ratio inthese steels as well as the size and distribution of TiN particles play a major role in determining themechanical properties, the resulting austenite grain size as well as the size of inclusionprecipitates. The best mechanical properties were obtained in the steel with a Ti/N ratio lower thanthe stoichiometric value. This steel also had the smallest austenite grain size after reheating aswell as the highest rate of dynamic recrystallisation during hot deformation. The nature and rate ofrecrystallisation seem to be determined by an intricate interplay between the size and distributionof titanium nitrides and the prevailing austenite grain size.