Modelling of isothermal formation of pearlite and subsequent reaustenitisation in eutectoid steel during continuous heating

Three different morphologies of pearlite have been formed isothermally at three different temperatures in a eutectoid steel. Moreover, the interlamellar spacing of the pearlite was calculated using the Zener and Hillert theoretical method. Experimental results suggest that the growth of pearlite is mainly controlled by volume diffusion of carbon in austenite, in the temperature range studied in this steel. In addition, a model that describes pearlite to austenite transformation during continuous heating in a eutectoid steel has been developed. The influence of structural parameters, such as interlamellar spacing and edge length of pearlite colonies, on the transformation kinetics has been experimentally studied and considered in the modeling. It has been found that the kinetics of pearlite to austenite transformation are slower the coarser the initial pearlite microstructure. Experimental validation of this model has been carried out and a good agreement (an accuracy level of higher than 90% in square correlation factor) between the experimental and calculated values has been found.