Abstract: Strain induced ferrite in a coarse austenite grain Q235 steel was investigated in detail by analyzing samples subjected to different strains. Results revel that the strain induced ferrite formed was influenced by the size ofaustenite grain. Ferrite nucleated on grain boundaries, annealing twin boundaries in large y grained sample at the early stage of deformation and upon further straining on deformation bands. Whereas, ferrite nucleates mainly on grain boundaries in small Y grained samples being insensitive to strain scale. With the increase of y grain size, nucleation on the deformation bands was apparently increased and with respect to that on grain boundaries.