Issue 74

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

VHCF regime. However, the Authors did not provide any explanation about the reasons that causes this change of fracture mechanism and how it is correlated with the change of slope of the S-N curves.

(a)

(b) Figure 3: S-N curves of SUJ2 steel: (a) qualitative behaviour based on the results of Akiniwa[8] (b) S-N curves digitized from the data of Akiniwa et al. [8].

Figure 4: S-N curves of the 40 Cr steel digitized from the data of Qian et al. [10].

Qian et. al. [10] studied the HCF and VHCF behaviour of a 40 Cr structural steel. The fatigue tests were performed using a rotary bending machine operating at a frequency of 52,5 Hz. All the specimens were quenched, tempered and polished at

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