Application of a Fast Phase Transformation Model on the Run Out Table of a Narrow Strip Hot Rolling Mill

• Applicant: Professor Dr.-Ing. Wolfgang Bleck
• Subject Area: Metallurgical, Thermal and Thermomechanical Treatment of Materials
• Term: from 2015 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 261177479

Bainitic steels serve the applications where high strength is needed and increasingly substitute micro-alloyed steels, for example common used grades known as S 600 MC and S 700 MC. Their microstructure is composed of slightly carbon enriched bainitic ferrite and carbide. The bainite transformation is rather complicated as it is partially diffusion controlled and the transformation mechanism changes with temperature. The current water controlling model on the Run-Out-Table (ROT) at the industrial plant has been shown to be invalid for these bainitic steel grades. The bainite transformation takes place below the bainite start (Bs) and above the martensite start temperature (Ms). Thus the time-temperature profile in the strip on the ROT must be controlled to lie in the most prompt bainite transformation temperature region so that the bainite transformation is the most feasible and unwanted phase transformation such as martensite or pearlite can be avoided. The bainite phase transformation model being developed in the project - Simulation, Optimisation and Control of Microstructure Evolution and Mechanical Properties during Hot Rolling of Multiphase Steels -, SPP1204, will be implemented in an industrial production line. The results of this knowledge transfer project will give more detailed information about the medium-wide strip cooling section and help to gain better understanding of the transformation processes. It will provide by full-scale experiments the options and constraints for further development of the SPP1204 bainite transformation model. This will ease future model and steel developments, reducing the use of trial and error experiments by applying scientific approaches in the product development process.

• DFG Programme: Research Grants (Transfer Project)
• Participating Institution: Hoesch Hohenlimburg GmbH