PREDICTION OF STATIC SOFTENING OF MICROALLOYED STEEL BY THE INTEGRATION OF FINITE ELEMENT MODEL WITH PHYSICALLY BASED STATE VARIABLE MODEL

  Abstract   Recovery and recrystallization phenomena and effects of microalloying elements on these phenomena are of great importance in designing thermomechanical processes of microalloyed steels. Thus, understanding and modeling of microstructure evolution during hot deformation leads to optimize the processing conditions and to improve the product properties.   In this study, finite element method was utilized to simulate thermomechanical parameters during hot deformation processes. FEM results then were integrated with physically based state variable models of static recovery and recrystallization combined with a realistic microstructural geometry. The thermodynamic software Thermo-calc was also used to predict present microalloying elements at equilibrium conditions. The model performance was validated using stress relaxation tests. Parametric studies were carried out to evaluate the effects of deformation process parameters on the microstructure development following hot deformation of the API-X70 steel