Dynamic recrystallization and recovery were two competing processes. Both may continue after hot deformation, such as during passes in multi-pass hot rolling processes, reducing dislocation density of materials and allowing larger plastic deformation to be achieved. The main objective of this research was to develop a set of mechanism-based unified viscoplastic constitutive equations which model the evolution of dislocation density, recrystallization and grain size during and after hot plastic deformation. This set of constitutive equations were determined for a C-Mn steel using an evolutionary programming optimization technique and implemented into the commercial finite element solver ABAQUS for process simulations. Numerical procedures to simulate multi-pass rolling were developed. Finite element analysis was carried out to simulate the evolution of grain size, dynamic/static recrystallization and recovery, and to rationalize their effects on the viscoplastic flow of the material in a two-pass hot rolling process.

Development of Dislocation-Based Unified Material Model for Simulating Microstructure Evolution in Multipass Hot Rolling. J.Lin, Y.Liu, D.C.J.Farrugia, M.Zhou: Philosophical Magazine, 2005, 85[18], 1967-87