ADRIAN Henryk AGH University of Science and Technology, Faculty of Metals Engineering and Industrial Computer Science


The diffusional transformation of pearlite to austenite takes place when the iron alloy with a matrix containing pearlite is heated to a temperature above A_c1. Development of the transformation contains two stages. The first stage is the formation of austenite nuclei. The second stage involves the growth of the austenite nuclei up to the moment of a complete transformation of the pearlite into austenite. The transformation rate depends on the parameters of the initial microstructure and also on the temperature transformation. Among the parameters of the initial structural the most important are: the thickness of a cementite and a ferrite plate (called interlamellar distance) and the size of the pearlite colony. Following the Roosz [1] a numerical model of the pearlite - austenite transformation has been developed. It allows for the calculation of the time of the transformation at an assumed temperature as well as to determine the TTT diagram for the assigned temperature range. The developed computer program was used to analyze the effect of parameters of the initial microstructure on the obtained TTT diagrams. The results of modeling the transformation showed a strong influence of the interlamellar distance on the transformation kinetics. Decrease of the interlamellar distance affect the reducing of the time needed to end the transformation. Analyzing the obtained results of the simulation can also be seen that the size of pearlite colonies has lower effect on the rate of the transformation of pearlite to austenite in comparison with the effect of interlamellar distance.