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) 1147–1152

European Conference on Fracture 2024 Fatigue and fracture behaviour of high-strength lath martensitic steel Mihaela Iordachescu a *, Patricia Santos a , Andrés Valiente a a Material Science Dpt., ETSI Caminos, Universidad Politécnica de Madrid, 5 Prof. Aranguren St., 28040-Madrid, Spain Abstract The paper addresses the fatigue and fracture behaviour of a low-alloy lath martensitic steel that conform a new class of high strength tendon-bars for structural engineering. In order to assess the damage tolerance of such bars, a failure assessment diagram (FAD) is constructed from experimental results by plotting the failure loads of fatigue-cracked cylindrical notched specimens against the cracked area, as respective fractions of the bearing load capacity and the cross section of the uncracked specimen. The FAD includes the theoretical regions where failure is respectively controlled by the steel yielding capacity and toughness. The positions occupied in the FAD by the experimentally obtained failure data indicate that toughness is sufficient to prevent the brittle failure. Thus, it can be concluded that the toughness and ductility of the lath martensitic steel provide the bars with a substantial level of crack resistance. © 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: High-strength martensitic steel; fatigue resistance; failure mechanisms; 1. Introduction The minimum tensile strength of 1GPa states the limit for high-strength steel bars to be used as tendons in structural engineering, particularly in pre- or post-stressed concrete structures (Valiente et al., 2016). In addition, the accurate geometrical configuration that they provide allows the reliable loading control inherent in the sustainability and resilience design criteria almost universally accepted today (Eurocode 3 for design of steel structures, parts EN 1993 1-9, 2005 and EN 1993-1-10, 2005). Until recently, such a high-tensile strength was supplied with adequate heat © 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

* Corresponding author. Tel.: +0-000-000-0000 ; fax: +0-000-000-0000 . E-mail address: mihaela.iordachescu@upm.es

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.2025.06.180