Hot rolling is one of the most important and complex deformation processes in steel manufacturing and is essential to final product quality. The objective of this study is to investigate viscoplasticity, dynamic recrystallization, and static softening of alloyed metal during hot rolling process. Gleeble hot compression tests were performed to provide experimental stress-strain curves at different temperatures and strain rates. An inverse finite element analysis was performed to calibrate the experimental curves. Viscoplastic models including a Johnson-Cook (JC) model, a Zerilli-Armstrong (ZA) model, and a combined JC and ZA model were developed. Dynamic recrystallization behavior was investigated and modeled based on single hot compression test. Work hardening rate curve and dynamic recovery curve were modeled to calibrate the kinetics of dynamic recrystallization. Double hit tests were designed and performed and static softening model was developed at varying interpass time, pre-strain, temperature, and strain rate. Subroutines accounting for developed viscoplasticity, dynamic recrystallization, and static softening were developed and implemented into a three-dimensional finite element model of round bar hot rolling. The combined JC and ZA model demonstrated better agreement with experimental data than other traditional models. Dynamic recrystallization occurred throughout the round bar during hot rolling and is significantly influenced by the plastic strain and temperature. Static softening occurred rapidly in the beginning of interpass and then slowed down. Compared to rolling speed, rolling temperature demonstrated more significant influence on dynamic recrystallization and static softening during round bar hot rolling --Abstract, page iv
