PSI - Issue 75

J. Havia et al. / Procedia Structural Integrity 75 (2025) 43–52 Havia et al./ Structural Integrity Procedia (2025)

46 4

Table 3. Deposition and welding parameters.

Operation

Travel speed [mm/s]

Wire feed rate [mm/min]

Voltage [V]

Current [A]

Note

Deposition of detail

25

8.5

18.2 21.0 22.3

140 175 255

Pulsed Pulsed

Deposition Pass 1 and 2 25

10.5 14.6

Pulsed Torch angle 35° and 10 ° pushing

Welding – Case 2

18.5

2.2. Residual stresses measurements Residual stresses transverse to structural detail and parallel to the loading direction, were measured with an X-ray diffraction (Stresstech Xtress G3 device). The measurements started from the fatigue critical weld toe or DED detail and conducted 30 mm along the base material. measurements results are shown on Fig. 4. The highest tensile residual stresses were measured in Case 2 specimens where single pass welding was used to join the AM part on the plate. The residual stress measurement from DED surface in Case 3 was not possible with X-ray diffraction withing the scope of this study as metallurgical features (grain size) and uneven surface prevented reliable measurement. The residual stresses were expected to behave in Case 3 similar way than in Case 1.

a

b

250

1.80

250

1.80

DED on top of the plate

DED part welded on the plate

200

200

1.70

1.70

150

150

1.60

1.60

FWHM( )

FWHM (°)

100

100

1.50

1.50

50

50

Residual stress [MPa]

Residual stress [MPa]

1.40

1.40

0

0

0

5

10

15

20

0

5

10

15

20

-50

1.30

-50

1.30

Distance from deposition edge [mm]

Distance from weld toe [mm] Residual stress Side 1

Residual stresses - Side 1

Residual stresses - Side 2

Residual stress - Side 2

[ ] - Side 1

[ ] - Side 2

FWHM(°): 0.0°

FWHM side 2

FWHM [°]

FWHM [°]

- Side 1

- Side 2

Fig. 4. Residual stress measurements for (a) Case 1 – DED on plate and (b) Case 2 DED feature welded on the plate.

2.3. Evaluation of notch stresses In addition to the nominal stress method, fatigue capacity of specimens was also analyzed using the effective notch stress (ENS) concept (Hobbacher & Baumgartner, 2024) with the reference radius of r ref = 1.0 mm and 4R method (Havia et al. 2025). Idealized finite element models were created from each specimen variation, using actual DED detail dimensions and local geometry at the fatigue critical location. The welded geometry and dimensions of the DED detail were measured using a 3D scanner (Hexagon Romer Absolute arm with AS1 laser scanner). Thickness of the deposited feature and local weld geometry were acquired from polished cross-sections (Fig. 3). On finite element models, an average wall thickness of the deposited feature was used. The notch was modelled using the ENS approach with 1 mm reference radius ( r ref ) with 64 elements applied over a 360° circumference, according to the mesh convergence study (Baumgartner & Bruder, 2013). ¼-symmetry models were created using a linear 8- Y ’ 70 GPa and poisons ratio of 0.33, see Fig. 5. Misalignment or welding distortions effects were not accounted for in the models.