PSI - Issue 79

Déborah de Oliveira et al. / Procedia Structural Integrity 79 (2026) 248–258

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2025) and geometric variations (Vieira et al., 2024). Added to it, it is necessary to ensure that fatigue life matches the project specifications without being hindered by the deposition. Sales et al. (2021), Ermakova et al. (2022) and Ermakova et al. (2023) investigated the fatigue behavior of wall structures produced by the Cold Metal Transfer (CMT) process using different wire feedstocks and testing methodologies. Despite differing in materials and specific testing conditions, all studies focused on understanding the influence of deposition direction on fatigue performance. In the study by Sales et al. (2021), super duplex stainless-steel walls were fabricated using ER2594 wire. Fatigue specimens were extracted and tested at 10Hz with a load ratio of R=0.1. The authors developed an S-N curve incorporating additional data from other alloys. Their findings showed that specimens extracted longitudinally to the deposition direction had superior fatigue strength, indicating pronounced material anisotropy. Similarly, Ermakova et al. (2022) produced wall structures using ER100S-1 wire, extracting specimens both parallel and perpendicular to the build direction. Fatigue tests were performed at 5Hz with the same load ratio (R=0.1), focusing on crack initiation and propagation. The results confirmed that specimen orientation affected crack development, although ductile fracture was observed regardless of orientation. In a subsequent study, Ermakova et al. (2023) employed ER70S-6 wire and focused specifically on fatigue crack growth behavior. Tests were conducted with maximum loads of 10kN and 11kN using a sinusoidal waveform at 5 Hz and R=0.1, with initial crack lengths around 20mm. Crack propagation was monitored via high-resolution imaging. Interestingly, orientation effects were load-dependent: at 10kN, horizontally oriented samples exhibited twice the fatigue resistance of vertical ones, whereas at 11kN, vertical specimens outperformed horizontal ones. These results suggest that while orientation may influence fatigue crack growth, the effect is not consistent and depends on the applied load. Collectively, these studies highlight the importance of deposition direction in CMT-processed components. While Sales et al. (2021) and Ermakova et al. (2022) observed that anisotropy due to deposition direction significantly affects fatigue performance and crack propagation, the findings from Ermakova et al. (2023) imply that this effect can be overridden by load conditions, indicating a more complex interaction between loading parameters and build orientation. In this sense, this work aims to contribute evaluating the fatigue life of a high strength low alloys steel (HSLA) produced by WAAM- CMT, in horizontal and vertical samples, considering the deposition direction. 2. Materials and Methods The 100-layers walls were deposited following the parameters proposed in the work of Novelino et al. (2022), Fig. 1 (a) and (b). Since it was a GMAW process, to produce the arc, a Fronius TransPuls Synergic 5000 was used. For the torch movements a cartesian robot Schneider Electric MAXR23-S42-H42-C42 was applied, having operational range of 800 mm, 800 mm and 500 mm in width, length and height, respectively. The shielding gas composition was composed of Ar + 18%CO 2 , at a flow rate of 20l/min. The material deposited was the HSLA ER70S-6, with the chemical and mechanical characteristics presented in Table 1. After the 100-layers walls were produced specimens were extracted in accordance with ASTM E466 (ASTM, 2014) the geometry and positioning can be observed in Fig. 1 (c) and (d), the specimens had a thickness of 2.00mm, width of 4.00mm, and a gage length of 8.00mm. The fillet

radius was 32.00mm, and the resulting cross-sectional area was 8.00mm². Table 1. Typical chemical composition and mechanical properties of ER70S-6 (Böhler, 2022) . Chemical composition 0.07% C 0.85% Si 1.50% Mn

97.58% Fe

Mechanical properties

Yield Strength MPa

Tensile Strength MPa

Elongation %

Charpy Impact Strength - J

450

575 Min

30

27 Min (-30C)