White Etching Areas in Bearing Steel 100Cr6

• Applicants: Professor Dr.-Ing. Christoph Broeckmann; Professor Dr. Joachim Mayer
• Subject Area: Mechanical Properties of Metallic Materials and their Microstructural Origins
• Term: from 2018 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 397802006

The overall goal of the applied project is to provide answers to open questions regarding the understanding of the formation mechanisms of WEA (White etching areas) and damage mechanisms leading to WEC (White etching cracks). Based on the research hypothesis 'Microstructural changes lead to crack formation' the following partial goals for the applied project emerge: 1. Reproducible creation of WEA/WEC on a rolling contact fatigue testing machine. 2. High resolution microstructure-analytical characterisation of the microstructural transformations in the region of the WEA. 3. Detailed investigations of the WEA regions with transmission electron microscopy. 4. Theoretical determination of the local temperature at the formation of the WEA. 5. With the help of a continuum mechanical, numerical simulation in mesoscopic scale conditions are to be identified, with which the observed microstructural changes in the region of the WEA can be explained. Using coupled numerical simulations, the phase transformation from the bainite structure to the supersaturated ferrite is to be considered as well as the stress concentration within the WEA formed due to their high strength. The study aims to prove that the stress in the WEA could rise very high, leading to crack formation in this area. An explicit simulation of the crack formation and -propagation will not be conducted in the proposed project.

• DFG Programme: Research Grants