Issue 74

P. Zuliani et alii, Fracture and Structural Integrity, 74 (2025) 385-414; DOI: 10.3221/IGF-ESIS.74.24

2. The fatigue notch factor (K f ), computed as the strength of the plain specimens and the strength of the notched specimens, is equal to 1.76 and it is almost constant in all the VHCF regime. According to the authors, the cause is the presence of the same failure origin (from surface defects) for both the geometries. Moreover, the authors also computed K f according to the Neuber relations, obtaining a value of 1.87. Since the difference is smaller than 5 %, they suggested that the notch fatigue factor of AlSi10Mg AM alloys can be computed by literature equations, but experimental tests are always recommended due to the large experimental variability.

Figure 13: S-N curve of the EN AW-6082 in the VHCF regime. Experimental data digitized from [21]

Figure 14: Definition of the stress intensity factor used in [6]

EBSD analyses have also been carried out and showed that there is no correlation between the grain size and the location. Consequently, the authors concluded that the grain size does not have a significant role in the fatigue response, which is mainly controlled by surface defects and irregularities. Finally, analyses of the fracture surfaces with the FESEM showed that the cracks originated from the specimen surface for plain specimens and from the border of the hole for notched specimens. The Authors conclude that internal defects are not critical for the failure of this type of material because the surface irregularities have a detrimental effect, since the specimens were tested in the as-built condition, without surface finishing.

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