Modelling of Kinetics and Dilatometric Behavior of Non-isothermal Pearlite-to-austenite Transformation in an Eutectoid Steel

Austenitization is an inevitable occurrence during the heat treatment of steels. Despite this consideration, less attention has been paid so far to the study of the formation of austenite as compared with the vast amount of research on its decomposition. That is because the steel properties depend basically on the transformation processes following austenitization. However, the initial austenitic condition is important to the development of the final microstructure and its mechanical properties. In this sense, continuous heating transformation diagrams (CHT) of different martensitic stainless steels and low carbon microalloyed steels were studied in previous work (1-3). With the introduction of dual-phase steels (4-7), partial austenitization in the intercritical temperature region became of technological interest and was widely studied (8-11). In that work, the authors emphasise the importance of the microstructure immediately before intercritical annealing. Roosz et al. (12) determined the influence of the initial microstructure on the nucleation rate and grain growth of austenite during isothermal treatment of a eutectoid plain carbon steel.