Observations of fatigue crack initiation in 7075-T651

Fatigue crack initiation behaviors throughout friction stir welded joints in AA7075-T6 in ultrasonic fatigue

“…In this case, micro defects dominate the failure mechanisms for that the fatigue crack generally initiated from the defects [27,28]. During the fatigue test, the cracked particles gave rise to a crack in the surrounding matrix [29], and eventually led to the final fatigue failure as shown in Fig. 8b~8d.…”

Effect of water vapor pressure on fatigue crack growth in Al–Zn–Cu–Mg over wide-range stress intensity factor loading

“…The material studied was 50.8 mm thick 7075-T651 plate taken from a large-scale heat prepared to simulate a typical legacy composition and investigated in an interdisciplinary program on multi-scale modeling for airframe fatigue prognosis [51][52][53]. The microstructure was peak aged, partially recrystallized and documented elsewhere [54].…”

Microstructure and Fatigue Properties of AlZn6Mg0.8Zr Alloy Subjected to Low-Temperature Thermomechanical Processing

“…Moreover, they found that fine Mn-rich particles, present in Al-Zn-Mg-(Mn) alloy, cause both increased low-cycle fatigue strength and crack toughness. Payne et al [18] found that phase particles (e.g., Al7Cu2Fe), which are harder than the matrix, become the precursors of cracking and when the number of fatigue cycles increase, they lead to propagation of cracking in the alloy matrix. On the other hand, the particles with hardness smaller than the matrix (e.g., Mg2Si) are not often privileged areas for initiation of cracks.…”