Phase-field simulation framework for modeling martensite and bainite formation in steel

In this study, we present a combination of phase evolution, chemical diffusion, temperature evolution, and finite strain elasto-plasticity to simulate the martensitic and bainitic transformation using the phasefield software library OpenPhase (OpenPhase, 2023). It is demonstrated how the carbon concentration significantly influences the martensite start temperature and the resulting microstructure. Furthermore, the kinetics of the transformation is strongly influenced by plasticity. For bainitic transformation, it is demonstrated how the holding temperature significantly influences carbon partitioning and the resulting microstructure: higher holding temperatures allow increased carbon diffusion and partitioning, stabilizing retained austenite, which is in good agreement with experimental observations. The present study offers new insights into the microstructure formation mechanisms during martensitic and bainitic transformations in low-carbon steel and offers a consistent modeling approach to model complex phase transformation scenarios in steel and other construction materials.