PSI - Issue 82

J. Blankenhagen et al. / Procedia Structural Integrity 82 (2026) 37–43

41

Blankenhagen et al. / Structural Integrity Procedia 00 (2026) 000–000

5

3. Results and discussion

Figure 2 presents the fatigue crack growth results for PBF-LB / M / 316L (left) and PBF-LB / M / Printdur ® HSA (right). For the purpose of comparison, literature data from Suryawanshi et al. (2017), Kluczyn´ski et al. (2020), and Schymura (2017) are also included.

Printdur® HSA:

316L:

10 -2

10 -2

PBF-LB/M/PDHSA 1 PBF-LB/M/PDHSA 2 PBF-LB/M/PDHSA 3 PBF-LB/M/PDHSA 4 PBF-LB/M/PDHSA 5

PBF-LB/M/316L 1 PBF-LB/M/316L 2 PBF-LB/M/316L 3 PBF-LB/M/316L 4 PBF-LB/M/316L 5

10 -3

10 -3

Schymura et al. (2017): (C+N) 0.85 (C+N) 0.96 (C+N) 1.07

Suryawanshi et al. (2017): PBF-LB/M/316L PBF-LB/M/316L Kluczynski et al. (2020): PBF-LB/M/316L PBF-LB/M/316L hot-rolled 316L

10 -4

10 -4

10 -5

10 -5

10 -6

10 -6

Schymura et al. (2017): hot-rolled 316L

10 -7

10 -7

2

4 6 8

10

20

40 60 80

100

2

4 6 8

10

20

40 60 80

100

∆ K inMPa √

∆ K inMPa √

(a)

(b)

Fig. 2: (a) Results of the crack propagation tests for PBF-LB / M / 316L with results from the literature for PBF-LB / M / 316L from Suryawanshi et al. (2017) and Kluczyn´ski et al. (2020) and results for conventionally manufactured (hot-rolled) 316L from Kluczyn´ski et al. (2020) and Schymura (2017)), (b) Results of the crack propagation tests for PBF-LB / M / Printdur ® HSA with results from the literature for (C + N) steels with varying (C + N) content between 0.85 % and 1.07 % from Schymura (2017) The crack growth curves of PBF-LB / M / 316L reveal a distinct dependence on build orientation. Parallel built spec imens ( ⊥ ) exhibit lower crack growth rates compared to perpendicular ( ∥ ) built ones. This behavior can be attributed to the layer-wise structure inherent to the PBF-LB / M process: cracks propagating perpendicular to the build direction must overcome interlayer boundaries, which act as local barriers to crack propagation. According to the literature data reported by Suryawanshi et al. (2017) and Kluczyn´ski et al. (2020), it was observed that for di ff erent build directions of PBF-LB / M / 316L, similar Paris law slopes with varying intercepts are present. The present results indicate a build direction-dependent variation of the slope and the intercept. It is evident that both Paris law parameters exhibit a dependence on the build direction, resulting in a change in their respective values. This finding suggests that the anisotropic microstructure induced by the PBF process has an influence not only on the crack initiation stage, but also on the subsequent propagation stage. Conventionally manufactured 316L showed slower crack growth rates compared to the additively manufactured specimens tested in this study. In the literature, additively manufactured specimens have also demonstrated better performance compared to conventionally manufactured materials Kluczyn´ski et al. (2020). This di ff erence could be attributed to the instability in the microstructure of PBF-LB / M materials and variations in the testing setup. The com parison highlights the significant impact of process-induced porosity, residual stresses, and microstructural anisotropy on the crack growth behavior. In contrast to PBF-LB / M / 316L, Printdur ® HSA showed no measurable dependence of crack growth rate on the notch orientation. The slopes of the vertically and horizontally notched specimens in the Paris curve were nearly identical, indicating that the crack propagation behaviour was close to isotropic. Despite this, the overall crack growth rates of Printdur ® HSA were comparable to those of additively manufactured 316L. Compared to conventionally ® HSA, along with its higher intrinsic strength, compensates for potential process-induced anisotropy. This behavior is likely related to the alloy’s interstitial solid-solution strengthening by carbon and nitrogen, which enhances both flow stress and resistance to localized plastic deformation (Riedner (2011); Mu´jica Roncery (2010)). Figure 3 (a) directly compares the crack propagation behavior of both additively manufactured alloys and shows the Paris law parameters for every tested specimen. Overall, PBF-LB / M / 316L and PBF-LB / M / Printdur ® HSA exhibit manufactured (C + N) steels, the specimen exhibited an increased rate of crack propagation. The absence of an orientation e ff ect suggests that the microstructure of Printdur