PSI - Issue 68

ScienceDirect Structural Integrity Procedia 00 (2025) 000–000 Structural Integrity Procedia 00 (2025) 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 68 (2025) 1038–1044

European Conference on Fracture 2024 Microstructure-based tensile indicator for assessing high-cycle and very-high-cycle fatigue of titanium alloys with additive and conventional manufacturing Xiangnan Pan a *, Zhiqiang Tao a,b , Youshi Hong a a LNM, Institute of Mechanics, Chinese Academy of Sciences, No.15 Beisihuanxi Road, Beijing 100190, China b College of Robotics, Beijing Union University, No.97 Beisihuan East Road, Beijing 100101, China Abstract Empirically, there is a quick estimate for the traditional fatigue limit of metallic materials at 10 7 cycles, which is a proportional value of the ultimate tensile strength (UTS), i.e. the so-called “fatigue ratio”. However, fatigue failure can still occur after 10 7 cycles, known as very-high-cycle fatigue (VHCF). In this case, the “true” fatigue limit is no longer a fixed proportion of the UTS, e.g. for the inclusion induced VHCF, the fatigue limit remains almost constant at 10 9 , 10 10 or 10 11 cycles and does not vary with the UTS. This phenomenon is more pronounced in additively manufactured alloys, where fatigue resistance is not solely related to the UTS in VHCF and even in high-cycle fatigue (HCF). Here, we summarize the basic metallurgical defects and typical microstructures of α+β titanium alloys produced by conventional and additive manufacturing, then extract their quantitative characteristics, compare their fatigue behaviors and correlate them with their tensile properties. Finally, we propose the possible form of an indicator that can rapidly assess the HCF and VHCF of the materials by combining UTS and elongation based on the detailed microstructure and the resulting specific failure type. © 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: very-high-cycle fatigue (VHCF); crack initiation and early growth; defect and microstructure; additive manufacturing; titanium alloy European Conference on Fracture 2024 Microstructure-based tensile indicator for assessing high-cycle and very-high-cycle fatigue of titanium alloys with additive and conventional manufacturing Xiangnan Pan a *, Zhiqiang Tao a,b , Youshi Hong a a LNM, Institute of Mechanics, Chinese Academy of Sciences, No.15 Beisihuanxi Road, Beijing 100190, China b College of Robotics, Beijing Union University, No.97 Beisihuan East Road, Beijing 100101, China Abstract Empirically, there is a quick estimate for the traditional fatigue limit of metallic materials at 10 7 cycles, which is a proportional value of the ultimate tensile strength (UTS), i.e. the so-called “fatigue ratio”. However, fatigue failure can still occur after 10 7 cycles, known as very-high-cycle fatigue (VHCF). In this case, the “true” fatigue limit is no longer a fixed proportion of the UTS, e.g. for the inclusion induced VHCF, the fatigue limit remains almost constant at 10 9 , 10 10 or 10 11 cycles and does not vary with the UTS. This phenomenon is more pronounced in additively manufactured alloys, where fatigue resistance is not solely related to the UTS in VHCF and even in high-cycle fatigue (HCF). Here, we summarize the basic metallurgical defects and typical microstructures of α+β titanium alloys produced by conventional and additive manufacturing, then extract their quantitative characteristics, compare their fatigue behaviors and correlate them with their tensile properties. Finally, we propose the possible form of an indicator that can rapidly assess the HCF and VHCF of the materials by combining UTS and elongation based on the detailed microstructure and the resulting specific failure type. © 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: very-high-cycle fatigue (VHCF); crack initiation and early growth; defect and microstructure; additive manufacturing; titanium alloy © 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.: +86 134 8872 5866. E-mail address: panxiangnan@lnm.imech.ac.cn * Corresponding author. Tel.: +86 134 8872 5866. E-mail address: panxiangnan@lnm.imech.ac.cn

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

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.2025.06.167