EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

There is a growing interest in applying carbide free bainitic microstructures for different hot rolled industrial applications. While the final microstructure should contain a high fraction of fine bainitic ferrite, mainly responsible for the strength, retained austenite should display a high stability (thermal and mechanical) if good ductility is also pursued. In addition, cementite precipitation and martensite in the microstructure should also be marginal, so that toughness is not impaired.
These microstructural requirements must align with to the scope of typical industrial hot rolling process. For example, the chemical composition must be based on lean C-Mn-Si-Cr-(Mo) alloying additions avoiding any phase transformation from the last rolling pass down to the coiling temperature and allowing the desired bainitic reaction to occur in the coiling temperature window.
In this work, we combine bainite phase transformation theory together with an extensive available knowledge of the microstructure and developed models, allowing for the prediction of relevant parameters such as chemical composition, hardenability, amount and scale of the different constituents as well as retained austenite stability.
This research is funded by Research Fund for Coal and Steel, grant number RFCS-2019-899482.