Issue 78

A. P. Soldatenkov et alii, Fracture and Structural Integrity, 78 (2026) 248-259; DOI: 10.3221/IGF-ESIS.78.15

thickness direction rather than their width for heat treatment 2 (Fig. 6), whereas the opposite was observed for heat treatment 1 [15]. For the heat treatment 2, the semi-axis ratios a/c of the crack fronts were >1 at the transition to the final fracture stage, while they were <1 for the heat treatment 1 (Fig. 11). In the latter case, an exception was one specimen, which had the semi elliptical crack front (similar to those for the heat treatment 2), in contrast to quarter-elliptical ones typical for the heat treatment 1 [15].

Figure 9: SEM-micrographs of the fatigue striations on the fracture surface in specimens with the heat treatment 2, registered in the fatigue tests at 850 (a) and 1200 MPa (b). The main directions of the crack propagation are indicated by arrows.

Figure 10: SEM-micrographs of the final fracture zones (a, b) on the specimens with vortex-like zones, reflecting texture of the Ti-5Al 5V-5Mo-1Cr-1Fe alloy fabricated by RSR.

Figure 11: The dependences of the semi-axis ratios a / c of the crack front at the transition to the final fracture stage on the corresponding SIF values K I,max for the specimens of the heat treatments 1 and 2.

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