PSI - Issue 66

Miu Hayashi et al. / Procedia Structural Integrity 66 (2024) 161–166 Author name / Structural Integrity Procedia 00 (2025) 000–000

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of the anodised film. However, in (c), no step was observed, as shown in (b). This suggests that in the low-stress amplitude range, the fracture originates from the cracking of the anodised film but not from the surface of the base metal just below the anodised film. Finally, Fig. 4(d) shows the fracture surface observation results of the An-20 ( σ a = 200 MPa, N f = 2.7 × 10 4 cycles). The figure shows a step shape and the high-stress-amplitude area of An-7 , indicating that the fatigue fracture originated from cracks generated during the formation of the anodised film.

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