Mossbauer spectroscopy was used to study the change of the magnetic field of iron atoms in ultrafine-grained low carbon ferritic steel. Particular attention was paid on the effect of impurities on the shift of Mossbauer peaks. From the change of Mossbauer subspectrum, it can be concluded that a non-equilibrium grain boundary region is developed within the ultrafine-grained ferritic steel during severe plastic deformation process. (c) 2006 Published by Elsevier B.V.