Model for cooling and phase transformation behaviour of transformation induced plasticity steel on runout table in hot strip mill

A mathematical model has been developed considering non-symmetric cooling i n the thickness direction of strip on a runout table (ROT), In order to sol ve a one-dimensional transient heat transfer equation including the heat ev olved from phase transformation, a finite element method was applied, coupl ed with thermodynamic and kinetic analyses. The heat capacities of each pha se and heat evolution owing to phase transformation were obtained from ther modynamic analysis of the Fe-C-Mn-Si system using Thermo-Gale. The phase tr ansformation kinetics of a transformation induced plasticity (TRIP) steel w ere derived by using continuous cooling experiments and thermodynamic analy sis. Heat transfer coefficients of strips on the ROT were, by applying an i nverse method, determined from actual mill data under various cooling condi tions. Using the developed model, temperature-time variations of plain carb on and TRIP steels on the ROT were calculated. The calculated results were in good agreement with the actual mill data. In addition, quantitative phas e evolution during cooling could also be predicted by the model. From this analysis, the optimum cooling pattern on a ROT for the production of TRIP s teel could be determined. MST/4662.