WEB A multiphase-field study of the interplay of elastic and chemical factors in the autocatalytic nucleation of bainitic subunitsFriday (25.09.2020) 13:35 - 13:50 M: Modelling and Simulation 1 Part of:
In the automotive industry in particular, the requirements placed on the materials used have grown steadily in recent years as a result of the need for reducing CO2 emissions.
Due to the combination of high strength and good ductility, bainitic steels offer a solution to make a significant contribution to reduce fuel consumption through economical lightweight automotive construction, without neglecting safety aspects.
Numerical methods, in particular the phase-field method, offer far-reaching potentials to further improve the properties of bainitic steels through a precise understanding of the microstructural changes during the manufacturing process. Despite the existing approaches to simulate the bainitic transformation with the phase-field method, there are still open questions.
In this work, based on the displacive theory of the bainite transformation, a multiphase-field model based on [Kubendran Amos et al. 2018] is adopted to model the growth and autocatalytic nucleation behavior of bainitic subunits. After the growth stoppage of the first bainitic subunit, the elastic energy landscape in the surrounding matrix phase is analyzed and well- and ill-favored regions are identified, which influence the nucleation behavior of a second subunit [Schoof et al. 2020]. During the carbon partitioning from the supersaturated bainitic ferrite, the chemical energy, driving the bainitic transformation, is reduced in the surrounding of the subunit due to carbon enrichment. Both the elastic as well as the chemical energy landscape are quantified and, based on the results, energetically favorable regions for the autocatalytic nucleation of subsequent bainitic subunits are proposed.