Kinetics, Mechanism and Modeling of Microstructural Evolution during Dynamic Recrystallization in a 15Cr-15Ni-2.2Mo-Ti Modified Austenitic Stainless Steel

Kinetics, mechanism and modeling of the microstructural evolution of a 15Cr-15Ni- 2.2Mo-0.3Ti modified austenitic stainless steel (alloy D9) during dynamic recrystallization (DRX) have been investigated. The kinetics of DRX has been investigated employing a modified Johnson- Mehl-Avrami-Kolmogorov (JMAK) model. The microstructural study shows that nucleation of new grains during DRX takes place on the parent grain boundary by a bulging mechanism. No significant texture component has been found to develop in the recrystallized matrix. A substantial amount of twins have been observed in the recrystallized matrix. It is proposed that twins play an important role during the nucleation and subsequent expansion of DRX in alloy D9, which in turn moderates the texture in the recrystallized matrix. An artificial neural network model has also been developed to predict the fraction of DRX and grain size, as a function of processing conditions. A good correlation between experimental findings and predicted results has been obtained.