PSI - Issue 76

Available online at www.sciencedirect.com

ScienceDirect

Procedia Structural Integrity 76 (2026) 3–10

© 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: Ti-6Al-4V; DED-LB/CW; Defects; Microstructure; K-T diagram; Fatigue assessment Abstract This work presents comprehensive fatigue test results utilizing machined specimens extracted horizontally from Ti-6Al-4V blocks manufactured by Direct Energy Deposition using Laser Beam and Coaxial Wire (DED-LB/CW). The experimental results act as basis to establish defect- and microstructure-based models applying the Kitagawa-Takahashi (K-T) approach and the modifications by El Haddad, Murakami and Chapetti. Three batches manufactured in two different DED-LB/CW systems were considered to achieve a variation in microstructure and micropore sizes. Fractographical analyses were executed to examine the size, location and shape of the crack-initiating features. Due to the parameter optimization carried out, Lack of Fusion (LoF) defects were avoided and only shrinkage and keyhole pores were detected. Fatigue Crack Growth (FCG) tests were performed using Compact Tension (CT) specimens to determine the long and effective crack growth thresholds. Kitagawa-Takahashi, El-Haddad, Murakami and Chapetti models were calculated combining fatigue strength, fractographical analysis, as well as fracture mechanics characteristics, achieving good fit with the experimental results. It can be concluded that the interaction between the defects and the microstructure is not negligible. Hence, an application of defect- and microstructure-based models using simplified pore size parameters such as Murakami ’ s √ area, enable a proper assessment of K-T diagrams for life predictions of Ti-6Al-4V manufactured by DED-LB/CW based on FCG behavior. 5th International Symposium on Fatigue Design and Material Defects FDMD 2025 Assessment of Kitagawa-Takahashi diagram for Ti-6Al-4V manufactured by DED-LB/CW: Evaluation of the interaction between defects and microstructure Xabat Orue a, *, Mikel Abasolo b , Eduardo Tabares a , Iban Quintana a a Tekniker, C/ Iñaki Goenaga 5, Eibar 20600 (Gipuzkoa), Spain b University of the Basque Country, Plaza Ingeniero Torres Quevedo 1, Bilbao 48013 (Bizkaia), Spain

* Corresponding author. Tel.: +34 673 748 369. E-mail address: xabat.orue@tekniker.es

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.2025.12.280