Effect of Preexisting Corrosion on Fatigue Cracking of Aluminum Alloys 2024-T3 and 7075-T6

Koch, Gerhardus H.; Hagerdorn, E.L.; Berens, Alan P.

doi:10.21236/ada430616

Cited by 6 publications

(2 citation statements)

References 15 publications

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“…A cutting edge problem is the prognosis of fatigue performance limited by the interaction of aluminium alloy static corrosion during ground‐basing and cyclic loading during flight 1–5 . Loading environment can range from salt water spray at sea‐level altitudes to very low water vapour pressures and temperatures at higher altitudes 5 .…”

Section: Introductionmentioning

confidence: 99%

Driving forces for localized corrosion-to-fatigue crack transition in Al-Zn-Mg-Cu

Burns

Larsen

Gangloff

2011

Fatigue &Amp; Fracture of Engineering Materials &Amp; Structures

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A B S T R A C T Research on fatigue crack formation from a corroded 7075-T651 surface provides insight into the governing mechanical driving forces at microstructure-scale lengths that are intermediate between safe life and damage tolerant feature sizes. Crack surface marker-bands accurately quantify cycles (N i ) to form a 10-20 μm fatigue crack emanating from both an isolated pit perimeter and EXCO corroded surface. The N i decreases with increasingapplied stress. Fatigue crack formation involves a complex interaction of elastic stress concentration due to three-dimensional pit macro-topography coupled with local microtopographic plastic strain concentration, further enhanced by microstructure (particularly sub-surface constituents). These driving force interactions lead to high variability in cycles to form a fatigue crack, but from an engineering perspective, a broadly corroded surface should contain an extreme group of features that are likely to drive the portion of life to form a crack to near 0. At low-applied stresses, crack formation can constitute a significant portion of life, which is predicted by coupling macro-pit and micro-feature elastic-plastic stress/strain concentrations from finite element analysis with empirical low-cycle fatigue life models. The presented experimental results provide a foundation to validate next-generation crack formation models and prognosis methods.Keywords AFGROW; aluminium; corrosion fatigue; finite element analysis; fatigue at notches; fatigue crack initiation; hydrogen embrittlement; life prediction. N O M E N C L A T U R Eb = fatigue strength exponent c = fatigue ductility exponent E = Young's modulus f = loading frequency K = stress intensity factor K IC = plane strain fracture toughness K max = maximum stress intensity k t−e = elastic stress concentration factor k t−ep = elastic-plastic stress concentration factor k ε = strain concentration factor K = stress intensity range L = longitudinal (rolling) grain orientation direction L p = pit height along the L-direction N i = crack formation cycles to ≈ 20 μm N f = total cycles to failure (N i + N p ) N p = crack propagation cycles to failureCorrespondence: James T. Burns.

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Section: Introductionmentioning

confidence: 99%

Driving forces for localized corrosion-to-fatigue crack transition in Al-Zn-Mg-Cu

Burns

Larsen

Gangloff

2011

Fatigue &Amp; Fracture of Engineering Materials &Amp; Structures

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“…Fatigue performance of aluminum alloys deteriorates in the presence of corrosion pits (Ref [16][17][18][19][20]. Several studies observed that the presence of pre-existing corrosion pits reduces the fatigue life of aluminum alloys considerably (by a factor ranging from 10 to 100) in comparison to that without corrosion pit ( Ref 15,19,21).…”

Section: Introductionmentioning

confidence: 99%

Crack Initiation from Corrosion Pit in Three Aluminum Alloys Under Ambient and Saltwater Environments

Sabelkin

Misak

Perel

et al. 2016

J. of Materi Eng and Perform

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Corrosion-pit-to-crack transition behaviors of three aluminum alloys using two pit configurations were investigated under ambient and saltwater environments. Fatigue stress ranges for crack initiation from a through-pit were less than that from a corner-pit in both environments in all three materials, while stress intensity factor ranges showed the opposite trend. Further, stress ranges or stress intensity factor ranges for crack initiation were less in saltwater than that in ambient environment for both pit configurations. Fatigue damage mechanisms in a test environment were similar for both pit configurations in all three materials. An empirical relationship is proposed to estimate pit-to-crack transition fatigue cycles.

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Synergy of corrosion-induced micro-cracking and hydrogen embrittlement on the structural integrity of aluminium alloy (Al-Cu-Mg) 2024

et al. 2017

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Effect of Preexisting Corrosion on Fatigue Cracking of Aluminum Alloys 2024-T3 and 7075-T6

Cited by 6 publications

References 15 publications

Driving forces for localized corrosion-to-fatigue crack transition in Al-Zn-Mg-Cu

Driving forces for localized corrosion-to-fatigue crack transition in Al-Zn-Mg-Cu

Crack Initiation from Corrosion Pit in Three Aluminum Alloys Under Ambient and Saltwater Environments

Synergy of corrosion-induced micro-cracking and hydrogen embrittlement on the structural integrity of aluminium alloy (Al-Cu-Mg) 2024

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