In-situ SEM study of fatigue micro-crack initiation and propagation behavior in pre-corroded AA7075-T7651

Song, Hang; Liu, Changchun; Zhang, Hao; Du, Juan; Yang, Xudong; Leen, Seán B.

doi:10.1016/j.ijfatigue.2020.105655

Cited by 23 publications

(16 citation statements)

References 23 publications

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“…Unbalanced segregation of grain boundaries is beneficial to the preferential attachment of micro voids to grain boundaries. The existence of a brittle intergranular phase can also weaken the grain boundary [26]. When the fatigue crack propagated, it would preferentially propagate to the weak grain boundary, resulting in the above different types of stepped morphology characteristics.…”

Section: Discussionmentioning

confidence: 99%

“…The main crack will hinder the propagation of the secondary crack, and the secondary crack usually only extends a small distance. The stress release caused by other crack propagation led to the decrease in the driving force of the secondary crack propagation, and the continuous propagation of the main crack would reduce or stagnation the propagation rate of the secondary crack [26]. Finally, the secondary crack propagation would stop to a certain extent.…”

Section: Discussionmentioning

confidence: 99%

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Fatigue Property and Small Crack Propagation Mechanism of MIG Welding Joint of 6005A-T6 Aluminum Alloy

et al. 2022

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In this study, metal inert gas welding (MIG) was applied to 4 mm thick 6005A-T6 aluminum alloy welding. Compared with other parts, the hardness of the weld zone (WZ) was the lowest, about 67 HV. There was the Softening in WZ, which might make WZ the weakest zone. Then, fatigue tests were carried out on MIG welded joints. All the fatigue specimens fractured at the weld toe of the lap joint, and the fracture was characterized by a cleavage fracture. Crack closure induced by oxide was observed during the steady propagation of the fatigue crack. Impurities hindered crack propagation, changed the direction of crack propagation, and appeared in stepped fatigue strip distribution morphology; in the process of the main crack propagation, the initiation and propagation of small cracks were easily restricted and hindered by the main crack, which slowed down the propagation rate and even stopped the propagation directly.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Fatigue Property and Small Crack Propagation Mechanism of MIG Welding Joint of 6005A-T6 Aluminum Alloy

et al. 2022

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“…Microobservation has shown that the corrosion pits caused the multisite crack sources and reduced the time of fatigue crack nucleation which decreased the fatigue life [21,22]. Song et al [23] have demonstrated that the crack deflection and coalescence were related to the corrosion pits. Kim et al [24] have found cracks being initiated from the pits that could be regarded as semielliptical surface micronotches.…”

Section: Introductionmentioning

confidence: 99%

Fatigue Crack Propagation Behavior of the 2195-T8 Aluminum-Lithium Alloy with a Precorroded Hole

Liu

Tian

et al. 2022

International Journal of Aerospace Engineering

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This work investigated the fatigue crack propagation behavior of the 2195-T8 Al-Li alloy with precorroded holes. The microstructure, crack growth path, and the fracture surfaces of the samples with the precorroded holes have been examined with scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and computed tomography (CT). The characteristics of the crack growth have been analyzed via fracture mechanics by employing the finite element method (FEM). The results showed that the bulk of the fatigue cracks had been initiated from the corrosion pits and corroded discontinuously and precipitated further to become intergranular. Owing to the superposed stress concentration caused by the corrosion pits, the porous region at the bottom of the precorroded hole had affected the crack propagation performance. Crack growth rates were different in multiple positions owing to the difference of K I at crack fronts.

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“…To date, many studies have been performed elucidating the effects of pre-corrosion on the fatigue performance of 7075 aluminum alloy [10][11][12][13][14][15][16][17][18][19][20][21][22]. For instance, Sankaran et al [12] investigated the effects of pitting pre-corrosion on the fatigue behavior of aluminum alloy 7075-T6 using cyclic fog-dry salt spray tests, and found that the fatigue lives of aluminum alloys could be dramatically reduced by pitting corrosion.…”

Section: Introductionmentioning

confidence: 99%

Actual Marine Atmospheric Pre-Corrosion Fatigue Performance of 7075-T73 Aluminum Alloy

Shi

Xiang²,

Tao³

et al. 2022

Metals

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Actual marine atmospheric pre-corrosion behavior and its effect on the fatigue performance of 7075-T73 aluminum alloy were studied by means of marine atmospheric outdoor exposure testing and fatigue testing. The surface and cross-sectional microstructures of aluminum alloy specimens after different numbers of days of exposure were analyzed. Localized pitting, and intergranular and exfoliation corrosion occurred during the outdoor exposure of aluminum alloy specimens in a marine atmosphere. The degree of severity of atmospheric corrosion increased with increasing duration of exposure. The effects of Fe-rich constituent particles (Al23CuFe4) and grain boundary precipitates (MgZn2) on the marine atmospheric corrosion behavior were discussed. In addition, when the exposure time was increased from 0 days to 15 days, the average fatigue life of aluminum alloy specimens decreased dramatically from about 125.16 × 104 cycles to 16.58 × 104 cycles. As the exposure time was further increased to 180 days, the average fatigue life slowly decreased to about 6.21 × 104 cycles. The fatigue fracture characteristics and the effect mechanism of marine atmospheric pre-corrosion on the fatigue life of 7075-T73 aluminum alloy were also analyzed.

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In-situ SEM study of fatigue micro-crack initiation and propagation behavior in pre-corroded AA7075-T7651

Cited by 23 publications

References 23 publications

Fatigue Property and Small Crack Propagation Mechanism of MIG Welding Joint of 6005A-T6 Aluminum Alloy

Fatigue Property and Small Crack Propagation Mechanism of MIG Welding Joint of 6005A-T6 Aluminum Alloy

Fatigue Crack Propagation Behavior of the 2195-T8 Aluminum-Lithium Alloy with a Precorroded Hole

Actual Marine Atmospheric Pre-Corrosion Fatigue Performance of 7075-T73 Aluminum Alloy

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