PSI - Issue 42

Lukas Lücker et al. / Procedia Structural Integrity 42 (2022) 368–373 Lukas Lücker / Structural Integrity Procedia 00 (2019) 000 – 000

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microstructural properties affecting the electrical resistance are comparable, but in the central axis the degree of forming-induced pre-damage differs. The effect of forming-induced damage could now be viewed in isolation and demonstrated via electrical resistance. A 2.9% higher resistance was detected for components with 90° shoulder opening angle, which can only be attributed to the higher degree of forming-induced pre-damage. Also, a correlation between the electrical resistance and the fatigue damage was found. Since the 30° specimen has a lower forming induced pre-damage, it allows more fatigue damage to fail, which results in a higher increase of electrical resistance. In future investigations, the resistance measurement will be coupled with micromagnetic measurements in order to separate the effects of different grain sizes or hardness on the resistance from the effect of damage. Furthermore the experimental setup needs to be adapted to a fatigue testing system to realize in-situ measurements. Acknowledgements The authors gratefully acknowledge the funding by the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG) for the subproject B01 within the Collaborative Research Center CRC/Transregio 188 “Damage controlled forming processes ” (Project number: 278868966). The authors further thank the Institute for Forming Technology and Lightweight Construction (IUL) of TU Dortmund University (subproject A02) for the provision of components and analyses in the framework of an excellent scientific collaboration. Parts of the results were elaborated by Lars Lingnau within his master thesis “Development of a test setup for DC based characterization of forming process-induced damage of case- hardened steel 16MnCrS5” (in German). References Borsutzki, M.; Thiessen, R.; Altpeter, I.; Dobmann, G.; Tschuncky, R.; Szielasko, K.: Nondestructive characterisation of damage evolution in advanced high strength steels. 18th European Conference on Fracture: Fracture of Materials and Structures from Micro to Macro Scale (2010) 1 – 9. Hering, O.; Dunlap, A.; Tekkaya, A.; Aretz, A.; Schwedt, A.: Characterization of damage in forward rod extruded parts. International Journal of Material Forming 13, 6 (2020) 1003 – 1014. Tekkaya, A.E.; Ben Khalifa, N.; Hering, O.; Meya, R.; Myslicki, S.; Walther, F.: Forming-induced damage and its effects on product properties. CIRP Annals - Manufacturing Technology 66 (2017) 281 – 284. Koch, A.; Bonhage, M.; Teschke, M.; Lücker, L.; Behrens, B.-A.; Walther, F.: Electrical resistance-based fatigue assessment and capability prediction of extrudates from recycled field-assisted sintered EN AW-6082 aluminium chips. Materials Characterization 169, 110644 (2020) 1 – 8. Lemaitre; J.: A continuous damage mechanics model for ductile fracture. Journal of Engineering Materials and Technology 107, (1985) 83 – 89. Samfaß, L.; Baak, N.; Meya, R.; Hering, O.; Tekkaya, A.E.; Walther, F.: Micro-magnetic damage characterization of bent and cold forged parts. Production Engineering Research and Development 14, 1 (2020) 77 – 85. Starke, P.; Walther, F.; Eifler, D.: Model-based correlation between change of electrical resistance and change of dislocation density of fatigue loaded ICE R7 wheel steel specimens. Materials Testing 60, 7-8 (2018) 669 – 677. Teschke, M.; Rozo Vasquez, J.; Lücker, L.; Walther, F.: Characterization of damage evolution on hot flat rolled mild steel sheets by means of micromagnetic parameters and fatigue strength determination. Materials 13 (11), 2486 (2020) 1 – 19. Tschuncky, R.; Altpeter, I.; Szielasko, K.: Electromagnetic techniques for materials characterization. Materials Characterization Using Nondestructive Evaluation (NDE) Methods (2016) 225 – 262.