Abstract: In this study, the effect of hot deformation on martensitic stainless steel was carried out in temperatures between 950 to 1100 °C and strain rates of 0.001, 0.01 and 0.1 s^-1. Two important dynamic recrystallization parameters, the critical strain and the point of maximum dynamic softening, were derived from strain hardening rate vs stress curves. Then the calculated parameters were used to predict the dynamic recrystallized fraction. Our results show that critical stress and strain increase with decreasing deformation temperature and increasing strain rate. The hot deformation activation energy of the steel is also investigated in the present work with 413 kJ/mol. Our experimental °ow curves are in fair agreement with the kinetics of dynamic recrystallization model.

Key words: Hot deformation, Dynamic recrystallization, Critical strain