PSI - Issue 54

ScienceDirect Available online at www.sciencedirect.com ^ĐŝĞŶĐĞ ŝƌĞĐƚ Structural Integrity Procedia 00 (2023) 000 – 000 Available online at www.sciencedirect.com ^ĐŝĞŶĐĞ ŝƌĞĐƚ Structural Integrity Procedia 00 (2023) 000 – 000 Available online at www.sciencedirect.com Procedia Structural Integrity 54 (2024) 361–368

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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 ICSI 2023 organizers 10.1016/j.prostr.2024.01.094 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 ICSI 2023 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 ICSI 2023 organizers * Corresponding author. Tel.: +49 4152 87 25 36; fax: +49 4152 87 425 36. E-mail address: nikolai.kashaev@hereon.de © 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 ICSI 2023 organizers Abstract The integrity of a load-bearing structure may degrade during service life due to undetected material defects or accidental damage. Additively manufactured structures are particularly susceptible to fatigue cracking due to stress concentration at possible surface notches or internal material defects. Despite the advantages of arc-based manufacturing techniques, it is still not comprehensively investigated how the manufactured parts fail under cyclic loading. This study aims to investigate the effect of material defects on the high-cycle fatigue behavior of WAAM-fabricated Ti-6Al-4V with dedicated thermal treatment. Furthermore, an emphasis was paid to investigating to which extent the fatigue life prediction model developed and validated for laser beam-welded Ti-6Al-4V joints can be transferred to WAAM-fabricated structures made from this alloy. The model is based on the NASGRO equation in which the short crack growth from the internal defect, such as lack of fusion defect, is taken into account. The results of the study show that by the use of the model, the minimum fatigue life of the fatigue specimens extracted from the WAAM-fabricated structure can be appropriately predicted. Some specimens showed lower predicted fatigue lives in comparison to the experimentally obtained ones. The reason could be due to the effective defect size, which was overestimated for irregular shape defects by analyzing the fracture surfaces of tested specimens. Thus, a conservative prediction of the fatigue life is achieved. Abstract The integrity of a load-bearing structure may degrade during service life due to undetected material defects or accidental damage. Additively manufactured structures are particularly susceptible to fatigue cracking due to stress concentration at possible surface notches or internal material defects. Despite the advantages of arc-based manufacturing techniques, it is still not comprehensively investigated how the manufactured parts fail under cyclic loading. This study aims to investigate the effect of material defects on the high-cycle fatigue behavior of WAAM-fabricated Ti-6Al-4V with dedicated thermal treatment. Furthermore, an emphasis was paid to investigating to which extent the fatigue life prediction model developed and validated for laser beam-welded Ti-6Al-4V joints can be transferred to WAAM-fabricated structures made from this alloy. The model is based on the NASGRO equation in which the short crack growth from the internal defect, such as lack of fusion defect, is taken into account. The results of the study show that by the use of the model, the minimum fatigue life of the fatigue specimens extracted from the WAAM-fabricated structure can be appropriately predicted. Some specimens showed lower predicted fatigue lives in comparison to the experimentally obtained ones. The reason could be due to the effective defect size, which was overestimated for irregular shape defects by analyzing the fracture surfaces of tested specimens. Thus, a conservative prediction of the fatigue life is achieved. Keywords: Wire and arc additive manufacturing; Ti-6Al-4V; fatigue analysis, short crack growth. 1. Introduction With the additive manufacturing (AM) process, in which the material is deposited layer by layer, any three dimensional shapes can be produced. Together with the great potential for weight reduction as well as cost, resource, and time savings and the best possible automation potential in production, this makes the process one of the major International Conference on Structural Integrity 2023 (ICSI 2023) Fatigue life assessment of WAAM-processed Ti-6Al-4V Nikolai Kashaev a, *, Anton Odermatt a , Lexuri Vázquez b , Pedro Álvarez b a Helmholtz-Zentrum Hereon, Institute of Materials Mechanics, Department of Laser Processing and Structural Assessment, Max-Planck-Str. 1, D-21502 Geesthacht, Germany b LORTEK, Basque Research and Technology Alliance (BRTA), Arranomendia kalea 4A, Ordizia 20240, Spain International Conference on Structural Integrity 2023 (ICSI 2023) Fatigue life assessment of WAAM-processed Ti-6Al-4V Nikolai Kashaev a, *, Anton Odermatt a , Lexuri Vázquez b , Pedro Álvarez b a Helmholtz-Zentrum Hereon, Institute of Materials Mechanics, Department of Laser Processing and Structural Assessment, Max-Planck-Str. 1, D-21502 Geesthacht, Germany b LORTEK, Basque Research and Technology Alliance (BRTA), Arranomendia kalea 4A, Ordizia 20240, Spain Keywords: Wire and arc additive manufacturing; Ti-6Al-4V; fatigue analysis, short crack growth. 1. Introduction With the additive manufacturing (AM) process, in which the material is deposited layer by layer, any three dimensional shapes can be produced. Together with the great potential for weight reduction as well as cost, resource, and time savings and the best possible automation potential in production, this makes the process one of the major * Corresponding author. Tel.: +49 4152 87 25 36; fax: +49 4152 87 425 36. E-mail address: nikolai.kashaev@hereon.de