Prediction of dynamic recrystallization kinetics and grain size for 410 martensitic stainless steel during hot deformation

Hot deformation behavior of AISI 410 martensitic stainless steel was investigated by conducting hot compression tests at a temperature range of 900 °C to 1150 °C and a strain rate of 0.001-1s−1. The relation between flow stress and Zener-Hollomon (Z) parameter was successfully modeled via the hyperbolic sine function under a wide range of deformation conditions, and the values were determined for the apparent activation energy, Q, and the empirical material constants A and n. Power-law equations show that the values of the peak and steady-state stress are related to the dimensionless parameter Z/A. The results also show that the flow stress deviates from linear dependence on the Z/A parameter at ασ < 0.8 and ασ > 1.2. The deviations reflect the power and exponential equations, respectively, for low and high stress levels. The way the peak and steady-state strains vary with the Z parameter was studied and best models were developed. A model based on the Avrami equation was developed to estimate the kinetics of the dynamic recrystallization (DRX) for different deformation conditions. The results of the model show that the Avrami exponent decreases as Z rises. In addition, the Avrami constant of k bears no distinct relation with Z. The optical microscopy observations of prior austenite grains confirm that the DRX grain size has an adverse relation with the Z parameter. The best relation between the DRX grain size and the Z/A ratio is proposed on the basis of the grain size measurements.