Dynamic Recrystallization of Ferrite with Particle-Stimulated Nucleation in a Low-Carbon Steel

Microstructure evolution of a low-carbon steel with the initial microstructure of ferrite matrix plus cementite particles during hot compression deformation was investigated at the strain rates of 0.001 s⁻¹, 0.01 s⁻¹, and 1 s⁻¹ at 973 K (700 °C) by means of field-emission scanning electron microscope, electron backscattered diffraction, and transmission electron microscopy. The results indicated that dynamic recrystallization (DRX) of ferrite took place at all of three strain rates, which can be classified as discontinuous DRX at 0.001 s⁻¹, 0.01 s⁻¹, and as continuous DRX at 1 s⁻¹. The formation of the nuclei of DRX of ferrite was mainly ascribed to the occurrence of particle-stimulated nucleation (PSN), accompanied with the lattice rotation and the formation of new high-angle boundaries. The occurrence of PSN was dependent on the development of a subgrain in the regions with high density of dislocations around cementite particles, without the need for the formation of the deformation zone.