PSI - Issue 68

Lukas M. Sauer et al. / Procedia Structural Integrity 68 (2025) 432–438 L. M. Sauer et al. / Structural Integrity Procedia 00 (2025) 000–000

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A comparison of the initial microstructure with the microstructure after defined numbers of cycles shows significant changes at the beginning of the fatigue test, followed by only minor changes. Subsequent studies will further analyse the microstructure, particularly focusing on the dislocation density through e.g., electron channeling contrast imaging. Additionally, the experimental setup allows the comparison of the individual influence of geometry, temperature and martensite transformation on the electrical resistance. Due to the high ductility of the base material and the stress ratio of R = 0.1, the geometry shows the highest influence on the electrical resistance, while the influence of temperature and martensite transformation is comparatively small. Future investigations will focus on further developing the method to separate und quantify the individual influence of microstructural damage, like dislocation density, voids or microcracks on the electrical resistance during fatigue. Acknowledgements The authors gratefully acknowledge the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG) for funding of the project “Alloying- and microstructure-based fatigue life characterisation and prediction of vacuum brazed AISI 304L/NiFeCrSiB joints in corrosive environments” (project no. 408904168), the subproject B01 “Measurement-based assessment and prediction of the interaction between ductile and cyclic damage on a macroscopic level” within the Collaborative Research Center CRC/Transregio 188 “Damage controlled forming processes” (project no. 278868966) and the project “Quantified evaluation of the influence of testing frequency on the fatigue behaviour of unalloyed steels for implementation in resource-efficient fatigue life prediction methods” (project no. 518776466). Furthermore, the authors further gratefully acknowledge the German Research Foundation and the Ministry of Culture and Science of North Rhine-Westphalia (Ministerium fuer Kultur und Wissenschaft des Landes Nordrhein Westfalen, MKW NRW) for financial support within the Major Research Instrumentation Program for the high-speed thermography system (project no. 444290516). References Hakamada, M., Kuromura, T., Chen, Y., Kusuda, H., Mabuchi, M., 2007. Influence of porosity and pore size on electrical resistivity of porous aluminum produced by spacer method. Materials Transactions 48, 32-36. https://doi.org/10.2320/matertrans.48.32 Lingnau, L.A., Heermant, J., Otto, J.L., Donnerbauer, K., Sauer, L.M., Lücker, L., Macias Barrientos, M., Walther, F., 2024. Separation of damage mechanisms in full forward rod extruded case-hardening steel 16MnCrS5 using 3D image segmentation. Materials 17, 3023. https://doi.org/10.3390/ma17123023 Lücker, L., Lingnau, L.A., Walther, F., 2022. 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