Finite element simulation and experimental analysis of dynamic recrystallization behavior during hot ring rolling of 17-4 PH stainless steel

In this research, the influence of ring rolling parameters on microstructure and dynamic recrystallization (DRX) behavior of 17-4 precipitation-hardened (PH) stainless steel was investigated. The ring rolling parameters included mandrel rotational speed, pressure roll velocity, temperature, and friction. The thermomechanical behavior was examined through hot compression tests conducted at temperatures in range of 850 to 1150 °C and strain rates from 10 −3 to 1 s −1 . The microstructural evolution and restoration mechanisms of alloy were analyzed using transmission electron microscopy. A DEFORM-3D finite element software was utilized to forecast the distributions of deformation parameters and Avrami factors (grain size and volume fraction of DRX) in the hot compressed samples. The findings show that the high temperature flow curves of 17-4 PH stainless steel exhibit characteristic features of DRX. The constitutive equations and DRX kinetics were established based on the flow stress data and restored microstructures. The key DRX mechanism in the studied steel is discontinuous DRX, facilitated by strain-induced boundary migration. The microstructural evolution of DRX grains as a function of the primary process parameters was modeled using the Johnson–Mehl–Avrami–Kolmogorov equation and subsequently validated through experimental ring rolling. A design-of-experiments approach was then employed to identify the most significant factors influencing DRX grain size and volume fraction in the as-rolled parts. Correlation between the simulated and experimental results confirmed the accuracy of the developed DRX models.