Effect of Cementite Particle Size on Dynamic Recrystallization of Ferrite in a Low Carbon Steel

摘要

The microstructure evolution of ferrite in a low carbon steel during hot uniaxial compression tests at 700℃ and 0.01s-1 was investigated by means of OM,SEM,EBSD and TEM.In order to investigate the effect of cementite particles size on dynamic recrystallization (DRX) of ferrite,two kinds of different microstructures consisting of ferrite with similar size and cementite particles with different sizes were adopted by quenching and tempering of a low carbon steel.The results showed that large cementite particles acted as nucleation sites for dynamic recrystallization (DRX) of ferrite by particle-stimulated nucleation (PSN) mechanism,due to the formation of large orientation gradient near them during hot deformation.In the earlier stage,DRX nuclei were mainly formed near cementite particles with size larger than 1m m.With increasing strain,the nuclei would also be formed near particles with size between 0.5 to 1m m.On the contrary,because of much smaller orientation gradient and pinning effect on the dislocation and sub-boundary,the cementite particles with size smaller than 0.3m m retarded dynamic recovery and DRX of ferrite.