PSI - Issue 76

Available online at www.sciencedirect.com

ScienceDirect

Procedia Structural Integrity 76 (2026) 35–42

© 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 the scientific committee of the FDMD 2025 chairpersons Keywords: Fatigue limit; Additive manufacturing (PBF-LB / M); As-built surface; Subsurface defects; Extreme Value Statistics (EVS); Ti6Al4V alloy Abstract This work presents a preliminary investigation into the estimation of fatigue limit in Ti6Al4V specimens produced via Laser Powder Bed Fusion of metals (PBF-LB / M) with surfaces in as-built conditions, by combining fracture mechanics with surface and volumetric defect characterization. Building upon a previously proposed approach that uses Extreme Value Statistics (EVS) to estimate the deepest micro-notch of PBF-LB / M as-built surfaces, this study presents a preliminary comparison between the estimated deepest notch from optical profilometry (OP), as a function of sample size, and the actual deepest surface notch measured across the entire outer surface of the gauge section of the specimen. In addition, internal and subsurface defects were characterized by X-ray computed tomography (CT) to provide a preliminary assessment of their relevance to fatigue behavior. The results show that EVS provides reliable estimates of the maximum depth, with less than 5% error for su ffi ciently large sample sizes. Finally, both surface roughness and subsurface defects led to similar e ff ective crack sizes and fatigue threshold estimates, suggesting their comparable roles in early crack initiation for the considered material. 5th International Symposium on Fatigue Design and Material Defects FDMD 2025 Extreme value analysis of the equivalent flaw size for fatigue limit estimation in additively manufactured Ti6Al4V specimens with as-built surface condition Daniele Rigon a , Eva Callegher a , Filippo Mioli a , Nicolo` Bonato b , Enrico Savio a , Giovanni Meneghetti a, ∗ a Department of Industrial Engineering, University of Padova, Via Venezia 1 35131, Padova, Italy b Department of Management and Engineering, University of Padova, Stradella San Nicola 36100 - Vicenza (Italy)

1. Introduction

Additive manufacturing (AM), and in particular Laser Powder Bed Fusion of metals (PBF-LB / M), is increasingly utilized in high-performance engineering fields for the production of complex metallic components. The layer-wise fabrication strategy not only enables unprecedented geometric freedom, but also leads to typical process-induced

∗ Corresponding author. Tel.: + 39-049-827-6751 E-mail address: giovanni.meneghetti@unipd.it

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 the scientific committee of the FDMD 2025 chairpersons 10.1016/j.prostr.2025.12.284