A model for deformation, temperature and phase transformation behavior of steels on run-out table in hot strip mill

Abstract

A numerical model was developed to simulate the deformation, temperature and phase transformation behavior in both thickness and width direction of strip on a run-out table (ROT) in hot strip mill. The heat capacity of each phase and the heat evolution due to phase transformation were obtained from the thermodynamic analysis of the Fe–C–Mn system. The phase transformation kinetics of the steels on ROT was derived from the continuous cooling experiments. A thermal model is developed using a finite element method based on the heat transfer coefficients of strips determined from the actual mill data. In order to calculate the deformation behavior of steels on the ROT of the hot strip mill, the elastic strain, the volumetric strain due to thermal contraction and phase transformation, the plastic strain, and the transformation induced superplastic strain were taken into account. A constitutive equation for the transformation induced superplastic deformation of steels, which is based on the concept of MIgration of Transformation Interface induced Plasticity (MITIP), was adopted in a finite element method coupled with the thermal, thermodynamic and kinetics models. Using the model, the temperature-phase-deformation behavior of the steel on the ROT was calculated.