Nozomi Komatsubara

DEVELOPMENT OF A METALLURGICAL MODEL FOR THE PREDICTION OF PEARLITE TRANSFORMATION AND ITS APPLICATION TO HIGH-CARBON SHEET STEEL PRODUCTION

A computer simulation model based on metallurgical theories have been developed in order to predict pearlite transformation during hot-run cooling in a hot strip production line. The model has been constructed on the basis of available theories; the regular solution sublattice model of Fe-C-Mn-Si systems for the estimation of thermodynamic parameters, thermodynamics and kinetics of phase transformation for nucleation and growth rate equations in isothermal condition. The model is able to predict kinetic information of pearlite transformation during continuous cooling and able to estimate the effect of latent heat evolution on the cooling behaviour of the materials. As a consequence the accurate prediction of transformation behaviour on a run-out table is accomplished for high-carbon steels where the effect of latent heat evolution is not negligible. It is demonstrated that the predicted cooling behaviours of steel sheets are in good agreement with the observed temperature profile of steel sheets on a run-out table in a hot strip mill. The optimisation procedure of cooling condition is discussed in order to improve the uniformity in mechanical properties within a high-carbon steel sheet.