Issue 74

M. C. Marinelli et alii, Fracture and Structural Integrity, 74 (2025) 129-151; DOI: 10.3221/IGF-ESIS.74.09

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(c) (d) Figure 7: SEM micrographs of the fracture surface: (a) RD, (b) TD. Elongation of microstructural constituents along the tensile axis: (c) RD sample, showing elongated pearlite and ferrite; (d) TD sample, highlighting a micro-void at the ferrite-pearlite interface (indicated by the circle). At Δε p = 0.3% (Fig. 8c), the RD and DD samples show continuous cyclic softening throughout their fatigue life. In contrast, the TD sample initially undergoes hardening of approximately 4%, followed by subsequent softening. Interestingly, the TD sample exhibits the highest stress amplitudes during the first 400 cycles. Between 3 and 400 cycles, the softening slopes for RD and TD are identical, while for RD and DD, the softening slopes become similar after 70 cycles.

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