Exfoliation Corrosion of 7075 Aluminum Die Forgings

Rinnovatore, James V.; Lukens, Karl F.; Corrie, John D.

doi:10.5006/0010-9312-29.9.364

Cited by 3 publications

(2 citation statements)

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“…For example, overaged 7075-T7 alloys are more resistant to exfoliation corrosion when compared to 7075-T6 alloys. In addition, Rinnovatore showed that in the T6 temper, exfoliation corrosion resistance was found to be greater for forgings produced from rolled bar stock than forgings from extruded bar stock [47]. Moreover, it was shown that rapid quenching from the solution temperature in cold water increased exfoliation corrosion resistance of forgings tempered to T6.…”

Section: International Journal Of Aerospace Engineeringmentioning

confidence: 99%

Exfoliation Corrosion and Pitting Corrosion and Their Role in Fatigue Predictive Modeling: State-of-the-Art Review

Hoeppner

Arriscorreta

2012

International Journal of Aerospace Engineering

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Intergranular attack (IG) and exfoliation corrosion (EC) have a detrimental impact on the structural integrity of aircraft structures of all types. Understanding the mechanisms and methods for dealing with these processes and with corrosion in general has been and is critical to the safety of critical components of aircraft. Discussion of cases where IG attack and exfoliation caused issues in structural integrity in aircraft in operational fleets is presented herein along with a much more detailed presentation of the issues involved in dealing with corrosion of aircraft. Issues of corrosion and fatigue related to the structural integrity of aging aircraft are introduced herein. Mechanisms of pitting nucleation are discussed which include adsorption-induced, ion migration-penetration, and chemicomechanical film breakdown theories. In addition, pitting corrosion (PC) fatigue models are presented as well as a critical assessment of their application to aircraft structures and materials. Finally environmental effects on short crack behavior of materials are discussed, and a compilation of definitions related to corrosion and fatigue are presented.

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Section: International Journal Of Aerospace Engineeringmentioning

confidence: 99%

Exfoliation Corrosion and Pitting Corrosion and Their Role in Fatigue Predictive Modeling: State-of-the-Art Review

Hoeppner

Arriscorreta

2012

International Journal of Aerospace Engineering

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“…Copper and its alloys are embrittled by liquid Sn, Pb, Bi, Pb-Bi, Sn-Pb, Pb-Ag, Hg, Ga, Ga-In, Ga-Hg, In, In-Hg, Zn, Li, Na, Sb, Th. 260,298,301,309,328,331,[333][334][335][336][337][338][339][340][341][342][343] Low melting point embrittler metals typically have little or no mutual solubility with copper and form no intermetallics (as is typical of embrittled/embrittling MIE metal pairs; see above); however, exceptions exist to this rule. 302 Although embrittlement of one metal by another is an atom-to-atom phenomenon that is hard to suppress, some strategies have been proposed to reduce its severity.…”

Section: Liquid Metal Embrittlementmentioning

confidence: 99%

Intermediate temperature embrittlement of copper alloys

Laporte¹,

Mortensen²

2009

International Materials Reviews

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Copper and its alloys generally display a severe reduction in ductility between roughly 300°C and 600°C, a phenomenon variously called "intermediate temperature embrittlement" or "ductility trough behaviour". This review of the phenomenon begins by placing it in the wider context of the high-temperature fracture of metals, showing how its occurrence can be rationalized in simple terms on the basis of what is known of intergranular creep fracture and dynamic recrystallisation. Data in the literature are reviewed to identify main causes and mechanisms for embrittlement, first for pure copper, and then for monophase and multiphase copper alloys. Coverage then turns to the "grain boundary embrittlement" phenomenon, caused by the intergranular segregation of even minute quantities of alloying additions or impurities, which appears to worsen dramatically the intermediate temperature embrittlement of copper alloys. Finally, metal-induced embrittlement, including in particular liquid metal embrittlement, is presented as a second mechanism leading to an exacerbation of the intermediate temperature embrittlement of copper and its alloys.

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Failure of Rifle Receivers Caused by Exfoliation

2019

ASM Failure Analysis Case Histories: Failure Modes and Mechanisms

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The lower receiver of the M16 rifle is an anodized forging of aluminum alloy 7075-T6. Degradation of the receivers was observed after three years of service in a hot, humid atmosphere. The affected areas were those in frequent contact with the user's hands. There was no question that the material failed as a result of exfoliation corrosion, so an investigation was undertaken, centered around the study of thermal treatments that would increase the exfoliation resistance and still develop the required 448 MPa (65 ksi) yield strength. The results of the study concluded that rolled bar stock should be preferred to extruded bar stock. Differences in grain structure of the forgings, as induced by differences in thermal-mechanical history of the forged material, can have a significant effect on susceptibility to exfoliation corrosion. Regarding thermal treatment, the results show conclusively that large changes in strength and exfoliation characteristics of 7075 forgings can be induced by changes in temperature or time of thermal treatment. With regard to the effect of quenching rate on exfoliation characteristics, a cold-water quench below 25 deg C (75 deg F) would appear to be far superior to an elevated-temperature quench to minimize exfoliation for 7075 forgings in the T6 temper.

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Exfoliation Corrosion of 7075 Aluminum Die Forgings

Cited by 3 publications

References 0 publications

Exfoliation Corrosion and Pitting Corrosion and Their Role in Fatigue Predictive Modeling: State-of-the-Art Review

Exfoliation Corrosion and Pitting Corrosion and Their Role in Fatigue Predictive Modeling: State-of-the-Art Review

Intermediate temperature embrittlement of copper alloys

Failure of Rifle Receivers Caused by Exfoliation

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