PSI - Issue 51

ScienceDirect Structural Integrity Procedia 00 (2022) 000–000 Structural Integrity Procedia 00 (2022) 000–000 Available online at www.sciencedirect.com Available online at www.sciencedirect.com ScienceDirect Available online at www.sciencedirect.com ScienceDirect

www.elsevier.com/locate/procedia www.elsevier.com/locate/procedia

Procedia Structural Integrity 51 (2023) 122–128

© 2023 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 the scientific committee of the ICSID 2022 Organizers Abstract For surgery, biodegradable magnesium alloys are considered promising candidates. The low corrosion resistance is advantageous since the implant is degraded in the presence of aqueous body fluids, supporting the human bone for a defined time and be fully degraded after this functional phase, making a second surgery for implant removal unnecessary. To design this phase and prevent early implant failure, precise knowledge of the degradation behavior over months and the correlating mechanical stability is essential. In vitro tests of the required duration are associated with enormous time and cost efforts. Therefore, a short-time method is developed to accelerate the degradation progress by anodic polarization without affecting the corrosion mechanism. The method is based on the corrosion behavior of Mg alloys under polarization, accompanied by increasing hydrogen evolution for increasing current densities, allowing conclusions to be drawn about the corrosion rate. Three-week immersion tests of the alloy WE43 with and without plasma electrolytic oxidation are the starting point. The time-dependent corrosion rates are to be reproduced by applying anodic polarization within three days. An experimentally determined relationship between current density and corrosion rate is used to design the polarization. The corrosion morphology of both testing strategies is analyzed by µCT. To evaluate the influence of the morphology on the mechanical stability, ex situ multiple amplitude tests are performed, allowing an estimation of the residual fatigue strength. The results show that a qualitative simulation of the hydrogen evolution rate is possible by applying polarization, achieving an enormous time saving. Due to a changed corrosion morphology with increased pitting tendency and the associated reduced residual fatigue strength, the method has to be considered as a worst-case evaluation allowing to exclude unsuitable Mg-based biomaterials right from the beginning, in particular before further preclinical studies. © 2023 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 the scientific committee of the ICSID 2022 Organizers Keywords: Biodegradable implants; WE43MEO; Kermasorb®; galvanostatic polarization; short-time testing method; residual fatigue strength 6th International Conference on Structural Integrity and Durability (ICSID 2022) Effect of galvanostatic anodic polarization on hydrogen evolution rate and residual fatigue strength of Mg alloys for implant use Nils Wegner*, Johanna Vergin, Frank Walther Chair of Materials Test Engineering (WPT), TU Dortmund University, Baroper Str. 303, D-44227 Dortmund, Germany Abstract For surgery, biodegradable magnesium alloys are considered promising candidates. The low corrosion resistance is advantageous since the implant is degraded in the presence of aqueous body fluids, supporting the human bone for a defined time and be fully degraded after this functional phase, making a second surgery for implant removal unnecessary. To design this phase and prevent early implant failure, precise knowledge of the degradation behavior over months and the correlating mechanical stability is essential. In vitro tests of the required duration are associated with enormous time and cost efforts. Therefore, a short-time method is developed to accelerate the degradation progress by anodic polarization without affecting the corrosion mechanism. The method is based on the corrosion behavior of Mg alloys under polarization, accompanied by increasing hydrogen evolution for increasing current densities, allowing conclusions to be drawn about the corrosion rate. Three-week immersion tests of the alloy WE43 with and without plasma electrolytic oxidation are the starting point. The time-dependent corrosion rates are to be reproduced by applying anodic polarization within three days. An experimentally determined relationship between current density and corrosion rate is used to design the polarization. The corrosion morphology of both testing strategies is analyzed by µCT. To evaluate the influence of the morphology on the mechanical stability, ex situ multiple amplitude tests are performed, allowing an estimation of the residual fatigue strength. The results show that a qualitative simulation of the hydrogen evolution rate is possible by applying polarization, achieving an enormous time saving. Due to a changed corrosion morphology with increased pitting tendency and the associated reduced residual fatigue strength, the method has to be considered as a worst-case evaluation allowing to exclude unsuitable Mg-based biomaterials right from the beginning, in particular before further preclinical studies. © 2023 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 the scientific committee of the ICSID 2022 Organizers Keywords: Biodegradable implants; WE43MEO; Kermasorb®; galvanostatic polarization; short-time testing method; residual fatigue strength 6th International Conference on Structural Integrity and Durability (ICSID 2022) Effect of galvanostatic anodic polarization on hydrogen evolution rate and residual fatigue strength of Mg alloys for implant use Nils Wegner*, Johanna Vergin, Frank Walther Chair of Materials Test Engineering (WPT), TU Dortmund University, Baroper Str. 303, D-44227 Dortmund, Germany

* Corresponding author. E-mail address: nils.wegner@tu-dortmund.de * Corresponding author. E-mail address: nils.wegner@tu-dortmund.de

2452-3216 © 2023 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 the scientific committee of the ICSID 2022 Organizers 2452-3216 © 2023 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 the scientific committee of the ICSID 2022 Organizers

2452-3216 © 2023 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 the scientific committee of the ICSID 2022 Organizers 10.1016/j.prostr.2023.10.077