Energy efficient manufacturing chain for advanced bainitic forging steels based on thermo-mechanical processing

• Applicant: Dr.-Ing. Jérémy Epp
• Subject Area: Metallurgical, Thermal and Thermomechanical Treatment of Materials
• Term: from 2017 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 327887503

The forging sector for the automotive industry nowadays seeks for more resource efficient processes. In order to reduce energy consumption with a possibility of significant cost reduction, this project aims at developing innovative process chains for new generation bainitic steels with continuous direct cooling after forging, replacing the traditional hardening and tempering processes. In the first phase of the project, new knowledge on thermomechanical processing of three advanced bainitic steels was generated, which allowed the definition of process window for these steels. The main results indicate great potential for application of these materials by means of thermomechanical routes on an industrial scale, which, in addition to reducing energy consumption, also make it possible to obtain a bainitic microstructure with improved mechanical properties. The investigations also enabled the further development and use of high impact scientific techniques such as in situ analyses using eddy current sensor and high energy synchrotron XRD as well as the realization of preliminary forging on an industrial scale, thus combining the scientific and technological aspects. In this framework, several effects and open questions were identified, which still need to be clarified. The second stage of the project has therefore as its main objective the improvement and transfer of the acquired knowledge to robust strategies for industrial production of machine components, in the sense of actual trends towards industry 4.0, based on sensor controlled manufacturing. The working plan is focused on three main areas: thermomechanical processing of components, post-processing steps and inspection of mechanical properties. Extensive physical and FEM-simulation as well as industrial scale forging experiments will allow the development of suitable treatment strategies for these steels. For this, further development and implementation of Eddy-current sensors combined with a controlled cooling unit will be realized in real thermomechanical process. The processed components will be characterized concerning the final microstructure and mechanical properties. The combination with additional surface hardening treatments will be further evaluated, as induction hardening, plasma nitriding and deep rolling/ shot peening. The achieved mechanical properties will then be intensively analyzed in terms of strength and ductility but also regarding the fatigue properties. In particular, the influence of the amount and stability of the retained austenite will be investigated, since it is seen as one of the major carrier for improved mechanical properties.

• DFG Programme: Research Grants
• International Connection: Brazil
• Cooperation Partner: Professor Dr. Alexandre da Da Silva Rocha