Spreading of intergranular corrosion on the surface of sensitized Al-4.4Mg alloys: A general finding

Jain, Swati; Lim, Mary Lyn; Hudson, John L.; Scully, John R.

doi:10.1016/j.corsci.2012.02.018

Cited by 124 publications

(45 citation statements)

References 34 publications

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“…7,14-17 Many papers assume the dissolution of β phase will occur because its breakdown potential, E b , is lower than the OCP of the alloy. 1,2,4,9,11,12,18 Lim et al showed that an incubation time to cause local acidification by applying a potential close to or above the E b of AA5083 was required to develop IGC on sensitized AA5083. 11,12 At the OCP of AA5083 in aerated solutions, which is typically at least 100 mV more noble than the E b of β phase, selective dissolution of β phase is not observed.…”

Section: -4mentioning

confidence: 99%

“…11,12 At the OCP of AA5083 in aerated solutions, which is typically at least 100 mV more noble than the E b of β phase, selective dissolution of β phase is not observed. 14 The only corrosion sites under these conditions were pits around intermetallic particles, such as Al 6 (Mn,Fe), which serve as cathodic sites and promote anodic dissolution around them at OCP.…”

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confidence: 99%

“…1,2,4,9,11,12,18 Lim et al showed that an incubation time to cause local acidification by applying a potential close to or above the E b of AA5083 was required to develop IGC on sensitized AA5083. 11,12 At the OCP of AA5083 in aerated solutions, which is typically at least 100 mV more noble than the E b of β phase, selective dissolution of β phase is not observed.14 The only corrosion sites under these conditions were pits around intermetallic particles, such as Al 6 (Mn,Fe), which serve as cathodic sites and promote anodic dissolution around them at OCP. 14,17 No clear explanation for the absence of IGC and β phase attack on sensitized AA5083 at its OCP has been provided in the literature.…”

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confidence: 99%

“…11,12 Galvanostatic and potentiostatic measurements on AA5083 samples showed a deeper degree of penetration of intergranular corrosion in samples with higher DoS, longer exposure time, higher applied potential, or higher current. Formation of continuous β phase along grain boundaries provides a pathway for deeper penetration of intergranular corrosion attack in highly sensitized AA5083 samples.…”

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Influence of the Altered Surface Layer on the Corrosion of AA5083

Seong

Yang

Scheltens

et al. 2015

J. Electrochem. Soc.

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The corrosion behavior of sensitized AA5083 in aerated and deaerated 3.5 wt% NaCl solutions has been studied. The results indicated that an altered surface layer (ASL) with a recrystallized microstructure having no β phase at the grain boundaries formed on sensitized AA5083 during polishing. The ASL prevented the exposure of β phase at the surface and its dissolution at the alloy open circuit potential, even though this potential was above the breakdown potential of bulk β phase. Selective dissolution of β phase was observed when a cathodic reaction caused an increase in localized pH near intermetallic particles or after removal of the ASL by etching to expose the grain boundary β phase. The different corrosion behavior of solutionized and sensitized AA5083 was clarified by testing etched samples. Removal of the ASL is therefore necessary to understand the initiation of intergranular corrosion on sensitized AA5083. © The Author(s) 2015. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. [DOI: 10.1149/2.0321506jes] All rights reserved.Manuscript submitted January 22, 2015; revised manuscript received February 16, 2015. Published February 27, 2015 Lightweight materials that provide good formability, high strengthto-weight ratio, weldability and corrosion resistance are desired for use in automotive and marine industrial and military applications. Wrought AA5XXX Al-Mg alloys are well known for these properties, and in recent years these materials have been used to replace heavier materials.1 However, Al-Mg alloys can be susceptible to intergranular corrosion (IGC) attack and intergranular stress corrosion cracking (IGSCC) because of sensitization, which involves the formation of the anodic β phase (Mg 2 Al 3 ) along the grain boundary. 2-4When an Al-Mg alloy containing more than 3 wt% Mg is exposed to room temperature over long periods of time or an elevated temperature (60∼180• C) over a shorter period of time, supersaturated Mg will diffuse to the grain boundary region and form β phase particles.5 Because the breakdown potential (E b ) of β phase (−0.95 V SCE ) 6 is more negative than the open circuit potential (OCP) of the alloy (−0.78 V SCE ), dissolution of β phase along grain boundaries can occur when the alloy is exposed in a corrosive environment. This phenomenon leads to IGC and also IGSCC when a tensile stress is present.1,7-10 Goswami et al. showed that the hardness of AA5083 gradually decreased with aging time, 10 which indicates removal of the strengthening element Mg from solid solution. Searles et al. found that the ductility of sensitized AA5083 during constant extension rate testing increased when a potential below the pitting potential of β phase was applied to the sample compared to testing at the OCP. 1 Jones et al. showed that the crack growth rates of AA5083 were ...

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Section: -4mentioning

confidence: 99%

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Influence of the Altered Surface Layer on the Corrosion of AA5083

Seong

Yang

Scheltens

et al. 2015

J. Electrochem. Soc.

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“…Alloying elements such as Mg, Cu, Zn and Si are usually added in aluminum to improve its mechanical properties and to increase its application. However aluminum alloys show deteriorated corrosion resistance compared to pure aluminum due to the increasing electrochemical inhomogeneity in metal matrix resulted from intermetallic strengthening precipitates [3][4][5][6]. For example, Al-Zn-Mg-Cu series alloys are widely used in aerospace industry because of their low density and high strength, but they are very susceptible to localized corrosion, such as pitting, intergranular corrosion (IGC) and exfoliation corrosion (EXCO).…”

Section: Introductionmentioning

confidence: 99%

Pitting corrosion of naturally aged AA 7075 aluminum alloys with bimodal grain size

Tian

Wang

et al. 2016

Corrosion Science

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Effect of the Thermo‐Mechanical Treatment on IGC Susceptibility of AA 5083 Alloy

Radetić¹,

Halap²,

Popović³

et al. 2014

Light Metals 2014

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This work reports on the effect of thermo-mechanical treatment on IGC susceptibility of the AA 5083 alloy. Specimens underwent varied amount of cold work and final annealing was conducted at 240°C. Extent of the cold work affected the IGC susceptibility of the alloy significantly. Microstructure characterization showed that depending on the amount of the cold work different deformation substructure was created, which, in turn, influenced -phase (Al 3 Mg 2 ). Formation of continuous film -phase at the grain boundaries was observed in the specimens that were subjected to lower degree of the cold work and which were IGC susceptible. Better corrosion resistance characterized the specimens that underwent higher degree of the cold work (over 30-40%) due to -phase precipitation in the form of discrete particles at the grain boundaries and in grain interiors.

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Spreading of intergranular corrosion on the surface of sensitized Al-4.4Mg alloys: A general finding

Cited by 124 publications

References 34 publications

Influence of the Altered Surface Layer on the Corrosion of AA5083

Influence of the Altered Surface Layer on the Corrosion of AA5083

Pitting corrosion of naturally aged AA 7075 aluminum alloys with bimodal grain size

Effect of the Thermo‐Mechanical Treatment on IGC Susceptibility of AA 5083 Alloy

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