PSI - Issue 68

Lucia Morales-Rivas et al. / Procedia Structural Integrity 68 (2025) 493–499 Lucia Morales-Rivas, Eberhard Kerscher / Structural Integrity Procedia 00 (2025) 000–000

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4.a) highly differ from the long crack behaviour, suggesting that for lower notch depths (and correspondingly increased notch sharpness) the predicted threshold might be overestimated, leading to non-conservative results in terms of safety. On the other hand, ( H results (listed in Table 4 and also plotted in Fig. 4.a) make it evident the difference in the definition with respect to the EHST parameter, ( . In this case, rather than the transition between the short crack and the long crack regime, ( H gets closer to the inflection point of the curve. According to the analysed cases, same trends for the three microstructures are not necessarily fulfilled either.

Table 4. Results from notch fatigue testing of advanced bainitic microstructures, corresponding to MECBAIN, as reported by Sourmail et al. (2017), and estimated according to the procedure described in the subsection 3.2. ∆ M /MPa M N /μm ∆ M /MPa M /μm 0.6C-1.5Si-890°C-220°C (114h) 1240 177 1336 3.8 0.6C-1.5Si-890°C-250°C (16h) 1346 69 1421 2.9 1C-2.5Si-950°C-250°C (16h) 1104 177 1187 5.2 Acc. to eqs. 6,7 Acc. to eqs. 2,8

Fig. 4. Evolution of the parameter (a) 1/k f as a function of the notch depth, a; and (b) O,