Effect of initial grain size on dynamic recrystallization of ferrite in a low carbon steel

The hot deformation behavior and the microstructure evolution of a low carbon steel with different initial grain sizes are investigated by uniaxial hot compression at deformation temperatures of 700 degreesC and 600 degreesC and strain rates of 10 s(-1) to 10(-3) s(-1). The effect of initial grain size and hot deformation parameter Z on dynamic recrystallization of ferrite is approached. The results indicate that under the present deformation conditions, the dynamic recrystallization of ferrite takes place in the low carbon steel. The decrease of initial grain size is not only of benefit to the dynamic recrystallization of ferrite at a certain Z value, but also leads to the increase of the critical values of Z for both the dynamic recrystallization of ferrite and the discontinuous dynamic recrystallization of ferrite. It is suggested that the fine ferrite formed by deformation enhanced transformation is beneficial to the occurrence of dynamic recrystallization of ferrite during hot deformation. Further refinement of the fine ferrite can be realized by the dynamic recrystallization of ferrite under a suitable Z value.