PSI - Issue 66

Jinta Arakawa et al. / Procedia Structural Integrity 66 (2024) 38–48 Author name / Structural Integrity Procedia 00 (2025) 000–000

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Schmid factors (SF) map of the area surrounding the location where the fatigue crack occurred is presented in Fig. 8. From these results, it was clear that the fatigue crack didn’t initiate at the grain having high SF value, necessarily. Therefore, in order to predict the grain where the fatigue crack will initiate, it is thought to be considering grain interaction by FEM based on crystal plasticity theory.

Crack tip

200μm

(a) 6.2 × 10 4 cycles

(c) 6.35 × 10 4 cycles

(b) 6.3 × 10 4 cycles

200μm

Fig. 6. Direct observation results and schematic images of fatigue crack initiation and propagation.

Fatigue crack initiation site

Magnified image

100μm

Fatigue fracture

Ductile fracture (Dimple)

100μm

Fig. 7. Fracture surface of Ti-22V-4Al alloy.