Fast model for phase transformations during cooling of pre-annealed multiphase steels

A thorough experimental and numerical analysis of phase transformations in a selected high strength steel was the general objective of the paper. Dilatometric tests were performed for a wide range of cooling rates. Two models based on a mean field approach were considered. The first was an upgrade of the Johnson-Mehl-Avrami-Kolmogorov equation. The second model was based on the Leblond equation. Both models were identified using inverse analysis of the experimental data. Simulations of various cooling schedules were performed to validate the models. Phase compositions for these cooling schedules were determined. Following this the effect of elements' segregation during solidification of steel on the occurrence of marteniste/bainite bands was accounted for using the developed models