PSI - Issue 68

Available online at www.sciencedirect.com Structural Integrity Procedia 00 (2025) 000–000 Available online at www.sciencedirect.com ScienceDirect

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Procedia Structural Integrity 68 (2025) 432–438

European Conference on Fracture 2024 Electrical resistance-based fatigue damage assessment of steels Lukas M. Sauer a *, Johannes L. Otto a , Lars A. Lingnau a , Jonas A. Ziman b , Peter Starke b,c , Frank Walther a a TU Dortmund Universtiy, Chair of Materials Test Engineering (WPT), Baroper Straße 303, 44227 Dortmund, Germany b University of Applied Sciences Kaiserslautern, Institute QM 3 , Department of Materials Science & Materials Testing (WWHK), Kaiserslautern 67659, Germany c Saarland University, Faculty of Natural Sciences and Technology, Saarbrücken 66123, Germany Abstract Electrical resistance measurements are a common method for the characterization of various microstructural properties and damage mechanisms, e.g., dislocation density, void volume fraction and microcracks. Additionally, influence affecting the electrical resistance, such as specimen geometry or temperature, must be considered. Therefore, ex-situ measurement techniques are frequently employed during fatigue due to their simpler measurement. However, ex-situ investigations have the potential to result in unintended influences due to disruptions, and only discrete states are analyzed limiting the characterization. Consequently, in situ measurements were performed in this study to investigate damage mechanisms and evolution during fatigue loading. To quantify and compensate for the influence of geometry, temperature, and martensite volume fraction change during fatigue tests, a complex experimental setup was developed for in-situ electrical resistance measurements. A new developed combination of measurement systems enables the direct transfer of measured strain to electrical resistance. The method was tested on high temperature vacuum brazed joints with a metastable austenite as base material and Ni-based filler metal. Finally, the change of the microstructure was evaluated through scanning electron microscopy analyses at different load cycles. © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of ECF24 organizers Keywords: Electrical resistvity; DCPD; fatigue and fracture mechanics; in-situ characterization; damage evolution; microstructure © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of ECF24 organizers – Dedicated on the occasion of the 75th birthday of Prof. Dr.-Ing. habil. Dietmar Eifler –

* Corresponding author. Tel.: +49 231 755 90167; fax: +49 231 755 8029. E-mail address: lukas.sauer@tu-dortmund.de

2452-3216 © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of ECF24 organizers

2452-3216 © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of ECF24 organizers 10.1016/j.prostr.2025.06.078