Modeling of dynamic recrystallization behavior of 21Cr-11Ni-N-RE lean austenitic heat-resistant steel during hot deformation

The dynamic recrystallization (DRX) behavior in 21Cr-11Ni-N-RE lean austenitic heat-resistant steel was investigated by hot compression tests within the temperature of 900–1200 °C and the strain rate of 0.01–10 s−1. The typical single-peak characteristic was observed in the most of resultant flow curves. On this basis, the related stress and strain peaks, recrystallization volume fraction were measured to quantify the kinetic models for DRX. A good agreement between the experimental and predicted results showed that the proposed kinetic equations can give an available estimate of the DRX evolution. In addition, the interpenetration of serrated grain boundary to viable recrystallized nuclei was considered to be a possible mechanism of initiation of DRX. Uniform and fine equiaxed grain structure could be obtained as a result of complete DRX, while abnormal grain growth may occur at high temperature and/or low strain rate after complete DRX. A DRX region diagram was developed to show the effect of deformation parameters on the DRX evolution; meanwhile a quantitative model was proposed to predict the final grain size in complete domain.