PSI - Issue 77

Jakob Blankenhagen et al. / Procedia Structural Integrity 77 (2026) 198–206 Author name / Structural Integrity Procedia 00 (2026) 000–000

202

5

shows a yielding behavior, which shows pronounced upper and lower yield strengths. For MT1 the upper yield strength is 595.45 MPa and the lower is 577.93 MPa. For MT2 the upper yield strength is 593.11 MPa and the lower is 579.04 MPa. Fig. 4 (d) shows the macroscopic fracture surface of specimen MT3. A pre-existing manufacturing defect is visible as a crack that goes from the surface into the interior of the plate, highlighted in blue, reducing the e ff ective cross sectional area by nearly half. This defect acted as a stress concentrator and caused failure within the AM material at approximately half the stress level as the other tested specimens. The corresponding surface crack prior to testing is shown in Fig. 4 (e). The defect most likely originated from residual stresses and contraction during the manufacturing process, which introduced a resting line containing a crack that served as a preferential site for fracture initiation. The tensile failure coincided precisely with this location, confirming that the defect, rather than the weld quality, governed the fracture of this specimen.

(a)

(b)

150 100 200 250 300 350 400 450 500 550 600 650 700 750

150 100 200 250 300 350 400 450 500 550 600 650 700 750

Failure in the S460 base material

Failure in the S460 base material

Failure in the weld

Failure in the Printdur® HSA base material

Failure in the weld

Printdur® HSA - S460, MIG: Filler material 18 8 Mn

8 1012141618 Printdur® HSA - S460, laser welded: LT1 LT2 LT3

MT1 MT2 MT3

50

50

0

0

0

2

4

6

8 1012141618

0

2

4

6

Fig. 3. (a) nominal stress-strain curves of the MIG welded specimens, (b) nominal stress-strain curves of the laser welded specimens

Table 3. Mechanical properties of the laser and MIG welded specimens Specimen Upper yield strength

Lower yield strength

Ultimate tensile strength in MPa

Elongation at fracture in %

R eH inMPa

R eL inMPa

® HSA – S460NL, laser welded

PBF-LB / M / Printdur

LT1 LT2 LT3

577.55 576.39

573.35 571.87

695.91 695.96 360.46

16.66

8.76 0.78

-

-

® HSA – S460NL, MIG welded, Filler material: G 18 8 Mn

PBF-LB / M / Printdur

MT1 MT2 MT3

595.45 593.11

577.93 579.04

702.24 699.04 419.30

15.76 16.29

-

-

1.01

3.3. Evaluation of the Strain Distribution with DIC

To further elucidate the failure mechanisms, the strain distribution during the tensile tests was analyzed using digital image correlation (DIC). Fig. 5 shows the true tangential strain in vertical direction for representative specimens LT1 (laser-welded) and MT2 (MIG-welded). Panels (a)–(f) correspond to LT1, and panels (g)–(m) to MT2.