PSI - Issue 77

7

Klusák Jan et al. / Procedia Structural Integrity 77 (2026) 432–439 Author name / Structural Integrity Procedia 00 (2026) 000–000

438

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Fig. 6. Critical distance curves for S460 NL (a), S690 QL (b), and S960 QL (c) steels (smooth as-machined samples)

5. Conclusions It has been demonstrated that surface quality significantly impacts the fatigue life of specimens. Polished samples have a longer fatigue life than as-machined samples. In the critical distance determination process, data from smooth samples and model notch samples are used. When the surface quality is similar (as-machined in both cases), the critical distance results are more consistent. These results can be used to make more reliable predictions about the fatigue life of samples or components with stress concentrations that differ from the model notch.