PSI - Issue 57

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ScienceDirect

Procedia Structural Integrity 57 (2024) 61–72 Structural Integrity Procedia 00 (2023) 000–000 Structural Integrity Procedia 00 (2023) 000–000

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

© 2024 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 Fatigue Design 2023 organizers Abstract Additive manufacturing is nowadays already used on aeronautical serial parts but very few of them are highly loaded critical components. Titanium alloy Ti-6Al-4V and laser powder bed fusion (L-PBF) manufacturing process are both part of the most studied materials and processes. Many studies have been dedicated to L-PBF produced Ti-6Al-4V on a large range of subjects from defect generation and microstructure evolution to fatigue life. Finishing processes are also a significant part of the studied processes as the micro-geometry of additively manufactured components remains the principal drawback for the production of fatigue subjected critical parts. In this work, fatigue bending tests are undertaken on Ti-6Al-4V L-PBF made coupons. For each of them, the loaded surface has been scanned using an optical profilometer to identify the population of micro-geometric surface features. The e ff ect of a chemical etching process on this population is described and the killer feature is highlighted in the population. Di ff erent indicators are discussed to understand if and how the killer feature can be predicted, knowing the loading conditions. It is concluded that Murakami’s √ area parameter may not be su ffi cient to determine the critical surface feature. A large scatter is observed in the fatigue strength, however, an approach based on the stress intensity range seems the most appropriate to identify the potentially critical surface micro-geometric features from the characterized population. © 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http: // creativecommons.org / licenses / by-nc-nd / 4.0 / ) Peer-review under responsibility of the scientific committee of the Fatigue Design 2023 organizers. Keywords: Additive Manufacturing ; Ti-6Al-4V ; Titanium alloys ; Fatigue Life ; Surface defects population ; L-PBF Abstract Additive manufacturing is nowadays already used on aeronautical serial parts but very few of them are highly loaded critical components. Titanium alloy Ti-6Al-4V and laser powder bed fusion (L-PBF) manufacturing process are both part of the most studied materials and processes. Many studies have been dedicated to L-PBF produced Ti-6Al-4V on a large range of subjects from defect generation and microstructure evolution to fatigue life. Finishing processes are also a significant part of the studied processes as the micro-geometry of additively manufactured components remains the principal drawback for the production of fatigue subjected critical parts. In this work, fatigue bending tests are undertaken on Ti-6Al-4V L-PBF made coupons. For each of them, the loaded surface has been scanned using an optical profilometer to identify the population of micro-geometric surface features. The e ff ect of a chemical etching process on this population is described and the killer feature is highlighted in the population. Di ff erent indicators are discussed to understand if and how the killer feature can be predicted, knowing the loading conditions. It is concluded that Murakami’s √ area parameter may not be su ffi cient to determine the critical surface feature. A large scatter is observed in the fatigue strength, however, an approach based on the stress intensity range seems the most appropriate to identify the potentially critical surface micro-geometric features from the characterized population. © 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http: // creativecommons.org / licenses / by-nc-nd / 4.0 / ) Peer-review under responsibility of the scientific committee of the Fatigue Design 2023 organizers. Keywords: Additive Manufacturing ; Ti-6Al-4V ; Titanium alloys ; Fatigue Life ; Surface defects population ; L-PBF Fatigue Design 2023 (FatDes 2023) Ti-6Al-4V L-PBF chemically etched components: from the surface micro-geometric characteristics to the fatigue strength David Melle´ a,b, ∗ , Etienne Pessard a , Franck Morel a , Daniel Bellett a , Rene´ Billardon c a Arts et Me´tiers Institute of Technology, LAMPA, HESAM University, 2 Boulevard du Ronveray, 49035 Angers, France b Safran Tech, Materials and Processes Department, Rue des Jeunes Bois, Chateaufort, 78772 Magny les Hameaux, France c Safran Transmission Systems, 18 Boulevard Louis Seguin, 92707 Colombes, France Fatigue Design 2023 (FatDes 2023) Ti-6Al-4V L-PBF chemically etched components: from the surface micro-geometric characteristics to the fatigue strength David Melle´ a,b, ∗ , Etienne Pessard a , Franck Morel a , Daniel Bellett a , Rene´ Billardon c a Arts et Me´tiers Institute of Technology, LAMPA, HESAM University, 2 Boulevard du Ronveray, 49035 Angers, France b Safran Tech, Materials and Processes Department, Rue des Jeunes Bois, Chateaufort, 78772 Magny les Hameaux, France c Safran Transmission Systems, 18 Boulevard Louis Seguin, 92707 Colombes, France

1. Introduction 1. Introduction

Additive Manufacturing processes are now part of the research and industrial landscape. From their beginning (Levy et al. (2003)) to their first use as rapid prototyping techniques (Kruth et al. (2007)) they have been continu ously improved in terms of the comprehension of the inherent physical phenomenon (Thijs et al. (2010); Parry et al. (2016)), the creation of di ff erent types of porosities (Gong et al. (2014)) and their e ff ect on microstructure (Xu et al. Additive Manufacturing processes are now part of the research and industrial landscape. From their beginning (Levy et al. (2003)) to their first use as rapid prototyping techniques (Kruth et al. (2007)) they have been continu ously improved in terms of the comprehension of the inherent physical phenomenon (Thijs et al. (2010); Parry et al. (2016)), the creation of di ff erent types of porosities (Gong et al. (2014)) and their e ff ect on microstructure (Xu et al.

∗ Corresponding author. Tel.: + 33-1 61 31 86 90. E-mail address: david.melle@safrangroup.com ∗ Corresponding author. Tel.: + 33-1 61 31 86 90. E-mail address: david.melle@safrangroup.com

2452-3216 © 2024 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 Fatigue Design 2023 organizers 10.1016/j.prostr.2024.03.008 2210-7843 © 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http: // creativecommons.org / licenses / by-nc-nd / 4.0 / ) Peer-review under responsibility of the scientific committee of the Fatigue Design 2023 organizers. 2210-7843 © 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http: // creativecommons.org / licenses / by-nc-nd / 4.0 / ) Peer-review under responsibility of the scientific committee of the Fatigue Design 2023 organizers.