PSI - Issue 77

ScienceDirect Structural Integrity Procedia 00 (2026) 000–000 Structural Integrity Procedia 00 (2026) 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 77 (2026) 376–381

© 2026 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 ICSI organizers Abstract This paper investigates the fatigue behaviour of untreated and heat-treated L-PBF AlSi10Mg aluminium alloy under proportional cyclic bending-torsion loading. Hollow round bars with a lateral hole were studied considering different bending-torsion ratios and loading levels for a stress ratio equal to zero. The applied heat treatment consisted of a low-temperature stress relief carried out at 250 °C for two hours. Crack initiation and growth were monitored in situ using a high-resolution digital camera. Crack initiation and crack growth directions were governed by the bending-torsion ratio, with the heat treatment showing no significant effect. In contrast, the fatigue life was affected by the bending-torsion ratio, the loading level, and the material condition. © 2026 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 ICSI organizers Keywords: Fatigue; bending-torsion loading; L-PBF; aluminium alloy. 1. Introduction AlSi10Mg aluminium alloy is an age-hardenable Al-Si-Mg alloy well-suited for use in laser powder bed fusion (L PBF) applications due to its low density, reduced thermal expansion, and high specific strength. The as-built microstructure of this alloy is characterised by a supersaturated aluminium matrix embedded within a connected eutectic Al/Si network. This architecture forms micro- scale α -Al cells enriched with Si precipitates, and the main International Conference on Structural Integrity Notch fatigue analysis of L-PBF AlSi10Mg aluminium alloy under bending-torsion loading R. Branco a *, J.D. Costa a , L.P. Borrego b,a , J. Jesus a , R.F. Fernandes a , J. Martins Ferreira a a Department of Mechanical Engineering, CEMMPRE, ARISE, University of Coimbra, 3030-199 Coimbra, Portugal b Department of Mechanical Engineering, Polytechnic University of Coimbra, Rua Pedro Nunes, Quinta da Nora, 3030-199 Coimbra Abstract This paper investigates the fatigue behaviour of untreated and heat-treated L-PBF AlSi10Mg aluminium alloy under proportional cyclic bending-torsion loading. Hollow round bars with a lateral hole were studied considering different bending-torsion ratios and loading levels for a stress ratio equal to zero. The applied heat treatment consisted of a low-temperature stress relief carried out at 250 °C for two hours. Crack initiation and growth were monitored in situ using a high-resolution digital camera. Crack initiation and crack growth directions were governed by the bending-torsion ratio, with the heat treatment showing no significant effect. In contrast, the fatigue life was affected by the bending-torsion ratio, the loading level, and the material condition. © 2026 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 ICSI organizers Keywords: Fatigue; bending-torsion loading; L-PBF; aluminium alloy. 1. Introduction AlSi10Mg aluminium alloy is an age-hardenable Al-Si-Mg alloy well-suited for use in laser powder bed fusion (L PBF) applications due to its low density, reduced thermal expansion, and high specific strength. The as-built microstructure of this alloy is characterised by a supersaturated aluminium matrix embedded within a connected eutectic Al/Si network. This architecture forms micro- scale α -Al cells enriched with Si precipitates, and the main International Conference on Structural Integrity Notch fatigue analysis of L-PBF AlSi10Mg aluminium alloy under bending-torsion loading R. Branco a *, J.D. Costa a , L.P. Borrego b,a , J. Jesus a , R.F. Fernandes a , J. Martins Ferreira a a Department of Mechanical Engineering, CEMMPRE, ARISE, University of Coimbra, 3030-199 Coimbra, Portugal b Department of Mechanical Engineering, Polytechnic University of Coimbra, Rua Pedro Nunes, Quinta da Nora, 3030-199 Coimbra

* Corresponding author. Tel.: +0-000-000-0000 ; fax: +0-000-000-0000 . E-mail address: ricardo.branco@dem.uc.pt * Corresponding author. Tel.: +0-000-000-0000 ; fax: +0-000-000-0000 . E-mail address: ricardo.branco@dem.uc.pt

2452-3216 © 2026 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 ICSI organizers 2452-3216 © 2026 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 ICSI organizers

2452-3216 © 2026 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 ICSI organizers 10.1016/j.prostr.2026.01.048