PSI - Issue 68

Mirko Teschke et al. / Procedia Structural Integrity 68 (2025) 936–941 M. Teschke and F. Walther / Structural Integrity Procedia 00 (2025) 000–000

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Magnification

MZ

500x

2,000x

a)

b)

10 µm

50 µm

DED-LB TNM HIP 90° PBF-EB/M TNM AB 90° PBF-EB/M TNM HIP 90° Fig. 3: SEM images of PBF-EB/M manufactured TNM-B1 alloy: a) As-built (AB); b) hot isostatic pressed (HIP) condition. c) d) 50 µm e) 10 µm f) 50 µm 10 µm

c)

b)

a)

20 µm

10 µm

100 µm

Fig. 4: SEM fractography, representation of three failure mechanisms: a) Lack-of-fusion (LOF) defects; b) Gas pores (GP); c) Microstructural (MS) features.

Fig. 5 shows the results from the fatigue tests in an S-N (Woehler) diagram. No significant difference between the test at RT and 800 °C can be observed, indicating an excellent high-temperature fatigue behavior. Despite the microstructural comparability of the three material states, significant differences can be recognized, with the two HIP states having the highest fatigue strength. Compared to the PBF-EB/M HIP state, the fatigue strength for the DED-LB state is even higher. In Fig. 5a, the failure mechanisms are marked for each test. While the AB state mainly failed at