Fatigue crack growth in D16-T and V95-T1 aluminum alloys in tests in sprayed and unsprayed NaCl solutions

Dotsenko, A. M.; Denisova, G. B.

doi:10.1007/bf01156533

Cited by 2 publications

(3 citation statements)

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“…In addition, the curves become close in the nearthreshold and high-amplitude regions, and the influence of the environment is leveled. These facts are in agreement with the data on behavior of high-strength aluminum alloys of the AI-Zn-Cu-Mg system [8][9][10]12]. Besides, these curves have a certain peculiarity, namely, two rectilinear segments are observed instead of one.…”

Section: Results Of Testssupporting

confidence: 90%

“…Its influence is equalized in the low-and high-amplitude regions of the diagram (see Fig. 2 b, d), which is typical of aluminum alloys [8][9][10]12]. The acceleration of the growth of cracks in aluminum alloys in the corrosive environment is explained by the enhancement of local plasticity by hydrogen (HELP mechanism [5,6]).…”

Section: Discussion Of the Resultsmentioning

confidence: 99%

“…Investigations of the growth of long cracks (macrocracks) in the corrosive environment were performed for high-strength aluminum alloys [7][8][9][10][11][12]. The corrosive environment was modelled by a 3.5% NaC1 solution.…”

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confidence: 99%

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Initiation and growth of corrosion-fatigue cracks near stress concentrators in V95pchT2 aluminum alloy

Ostash¹,

Kostyk²,

Makoviichuk³

et al. 1999

Mater Sci

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We investigate the kinetics of small fatigue cracks starting from notches in samples of V95pchT2 aluminum alloy in air and in a 3.5% NaCI solution. The influence of salt water is manifested in the initiation of pits on the notch surface and subsequent accelerated growth of small cracks (2-3 times faster than in the laboratory air). The size of an initial macrocrack a i does not depend on the level of stress or strain, notch radius, or environment and is equal to the characteristic distance d* = 100 ~m of the prefailure zone which is a material constant. The effect of crack closure in the presence of a corrosive medium is observed at the crack length a > 100 ~m. Within the frameworks of the approach proposed earlier for the study of initiation of a macrocrack near a notch, the basic dependences of values of local stresses or strains on the duration of the period of initiation of a macrocrack with length a i = d* are established, and the standard diagrams of cyclic crack resistance are constructed for V95pchT2 aluminum alloy at the stage of macrocrack growth in air and in a 3.5% NaCI solution.A corrosive environment substantially accelerates fatigue processes in the vicinity of stress concentrators in the form of clinched openings, fillets, notches, etc. Such a fatigue failure is often observed in the long-term operation of structural parts, made of high-strength aluminum alloys, of aircrafts and ships. It was established that surface pits appear as a result of the action of the corrosive environment [1,2]. These pits serve as nuclei of microcracks and cause their further development. Moreover, in aluminum alloys, pits appear near inclusions of the secondary phases rich with iron and silicon [ 1 ]. The degree of corrosion damage depends on the acting stresses and type of corrosion [2]. According to the Rebinder effect, the adsorption action of the corrosive environment, in particular of C1-ions, promotes an increase of plastic deformation in the surface layer which is manifested in an increase in dislocation density [3]. It is obvious that a decrease of the macroplasticity parameters ~g and ~5 of aluminum alloys by 10-20% reflects the absorption influence of the corrosive environment [4]. In the neighborhood of micro-and macrocracks, the action of the environment is even more substantial. This effect is characterized by the mechanism of enhancement of the local microplasticity in the presence of hydrogen known as the HELP mechanism [5,6]. This mechanism is inherent to high-strength aluminum alloys.The corrosive environment intensifies the development of fatigue cracks. Investigations of the growth of long cracks (macrocracks) in the corrosive environment were performed for high-strength aluminum alloys [7][8][9][10][11][12]. The corrosive environment was modelled by a 3.5% NaC1 solution. It was established that this environment accelerates the growth of both fatigue macrocracks ( 2-3 times in comparison with the growth in air) and fatigue cracks which are short from the microstructural point of view and physically ...

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Section: Results Of Testssupporting

confidence: 90%