PSI - Issue 68

Takanori Ito et al. / Procedia Structural Integrity 68 (2025) 420–424

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Takanori Ito et al. / Structural Integrity Procedia 00 (2025) 000–000

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Fig. 3. (a) The relationship between stress amplitude and number of cycles to failure in simulated HAZ specimens. (b) The relationship between fatigue strength and Vickers hardness.

3.2. The fatigue characteristics confirmed by using fatigue tests of cruciform fillet welded joints. An investigation was conducted to confirm whether the fatigue cracks were indeed originating from the HAZ. Figure 5 shows an image of the weld toe after fatigue testing. As shown, it was found that fatigue cracks were initiated from the HAZ microstructure, and fatigue failure occurred in the grinded area. Figure 6 shows the number

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Fig. 5. An optical microscope image of the fractured test specimen.

Fig. 4. The relationship between the fatigue strength normalized by Vickers hardness into average grain size.

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Fig. 6. The stress range and number of cycles obtained from the fatigue tests of cruciform fillet welded joints in conventional and developed steels.