PSI - Issue 23

Mattias Calmunger et al. / Procedia Structural Integrity 23 (2019) 215–220

220

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M. Calmunger et al. / Structural Integrity Procedia 00 (2019) 000–000

111

001

a)

101

b)

5 µm

5 µm

10 µm

10 µm

Fracture sur face, view II

Fracture sur face, view II

Cross section, view III

Cross section, view III

Fig. 6. Fracture surface and corresponding underlying microstructure for a specimen built in 90 ◦ and tested in LCF at ∆ ε = 1 . 3 %: a) overlayed ECCI image and b) overlayed EBSD map. The inserts in a) shows the cellular dendritic structure. On the fracture surface immediately above the cellular dendrites, the striation spacing is reduced (pointed out by the white arrow).

• The crack propagation was potentially influenced by interdendritical tearing of cellular dendritic structures for the specimen with 90 ◦ build direction. • The striation-like features from the cellular dendritic structure could easily be mistaken for regular fatigue striations although they represent a di ff erent fracture mechanism. • The interdendritical tearing was associated with less subsurface plastic deformation compared to fracture from regular fatigue striations.

Acknowledgements

This research has been funded by the Swedish Energy Agency and Siemens Industrial Turbomachinery AB through “Turbines for Future Energy Systems”, Grant No. 44112-1, the support of which is gratefully acknowledged.

References

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