Development of New Damage Tolerant Alloys for Age-Forming

Starink, M.J.; Sinclair, Ian; Gao, Nong; Kamp, N.; Gregson, P.J.; Pitcher, P.D.; Levers, Andrew; Gardiner, S.

doi:10.4028/www.scientific.net/msf.396-402.601

Cited by 31 publications

(29 citation statements)

References 8 publications

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“…To be able to compare the data in Fig 14a with the measured hardness data (Fig. 1) it should be noted that for Al-Cu-Mg alloys the hardness for aged conditions is not proportional to proof strength [54]. Proportionality is only observed when strengthening is either dominated by clusters (i.e.…”

Section: Heat Treatment -Microstructure -Strength Modelmentioning

confidence: 97%

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VPPA welds of Al-2024 alloys: Analysis and modelling of local microstructure and strength

Wang

Lefebvre

Yan

et al. 2006

Materials Science and Engineering: A

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The microstructural features of variable polarity plasma arc welded Al-Cu-Mg 2024-T351 with 2319 filler have been studied by TEM, SEM and DSC. Fusion zone, partial melting zone, resolutionising zone, overageing (for S phase), peak ageing (for S phase) and under ageing zones (for S phase) have been identified. The Ω phase has been observed between re-solutionising zone and peak ageing zone. The hardness profile contains two peaks. The microstructure development, and resulting hardness and yield strength profiles are modelled using a model which combines primary precipitation, resolution, partial/full melting and resolidification (Scheil type) and reprecipitation, in a two precipitate -two mechanism approach. Hardness profiles and microstructures are accurately predicted. The hardness peak in the re-solutionising zone is due to re-solutionising and subsequent Cu-Mg co-cluster formation; and the second hardness peak is caused by S phase strengthening.

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Section: Heat Treatment -Microstructure -Strength Modelmentioning

confidence: 97%

“…λ 1 and λ 2 were chosen such that they represent the data in Ref. [54], yielding λ 1 = 2. The resolutionising and reageing by co-cluster formation that occurs when T eq approaches 500ºC can explain the magnitude of the second hardness peak well.…”

Section: Heat Treatment -Microstructure -Strength Modelmentioning

confidence: 99%

VPPA welds of Al-2024 alloys: Analysis and modelling of local microstructure and strength

Wang

Lefebvre

Yan

et al. 2006

Materials Science and Engineering: A

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“…Details on production route for this alloy are given in Ref. [20]. After solution treatment at 768K, water quenching and stretching by 2.5%, the alloy was left at room temperature for a few months before further ageing at 423K.…”

Section: Methodsmentioning

confidence: 99%

Activation energy determination for linear heating experiments: deviations due to neglecting the low temperature end of the temperature integral

Starink

2006

J Mater Sci

127

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Model-free isoconversion methods which use approximations of the temperature integral are generally reliable methods for the calculation of activation energies of thermally activated reactions studied during linear heating. These methods generally neglect the temperature integral at the start of the linear heating, I (T o ). An analytical equation is derived which describes the deviations introduced by this approximation.It is shown that for most reactions encountered this assumption does not have a significant influence on the accuracy of the method. However, in cases where T o is within about 50 to 70K of the reaction stage to be investigated and activation energies are relatively low, significant deviations are introduced. It is shown that some of the published thermal analysis work on activation energy analysis of reactions occurring at relatively low temperatures is affected by these deviations. Examples are specific cases of dehydration reactions, cure reactions and cluster formation in Al alloys.

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“…Li additions to Al-Cu(-Mg) alloys are known to have a beneficial influence on fatigue crack growth rate, whilst precipitation is modified by formation of δ' (Al 3 Li) precipitates [5,6] and an expected change in rate of S phase precipitation [7]. Thus Li additions can significantly alter both the main properties and the thermomechanical processing required to obtain optimum properties.…”

Section: Introductionmentioning

confidence: 99%

“…A group of potentially age formable alloys around the composition range Al-(2-4)Cu-(1-2)Mg-(0.2-1.6)Li (wt%) with Mn, Zr and/or Sc additions has been investigated. Extensive analysis of the microstructure [5,7] and mechanical properties [4,8], in combination with modelling of the composition-processing-property relations, was used in an iterative process in the development and optimisation of the alloys. Following the earlier work which focussed on microstructural analysis and modelling of strength or fatigue crack growth micromechanics, the main aim of the present paper is to analyse the physical aspects that are responsible for the balance between creep rate during age forming and the resulting mechanical properties.…”

Section: Introductionmentioning

confidence: 99%

Relations between microstructure, precipitation, age-formability and damage tolerance of Al–Cu–Mg–Li (Mn, Zr, Sc) alloys for age forming

Starink

Gao

Kamp³

et al. 2006

Materials Science and Engineering: A

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Age forming of Al based alloys for damage tolerant applications requires an alloy with good age formability and good post-forming mechanical properties. To investigate optimisation of this balance, several newly designed Al-Cu-Mg-Li (Mn,Zr,Sc) alloys were subjected to artificial ageing representative of age-forming. It was seen that combinations of yield strength and fatigue crack growth resistance could be achieved that are at least comparable to the incumbent damage tolerant material for such applications, whilst creep rates at the ageing temperatures applied were better than those achieved in commercially applied age forming processes of heat treatable Al based alloys. Coarse grain structure and high Li content are associated with good fatigue crack growth resistance but reduce age formability. The underlying physical aspects responsible for the balance between creep rates and resulting properties are discussed. The metallurgical and micromechanical mechanisms analysed and discussed provide a framework for optimisation of composition and forming conditions for age forming of damage tolerant parts.

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Development of New Damage Tolerant Alloys for Age-Forming

Cited by 31 publications

References 8 publications

VPPA welds of Al-2024 alloys: Analysis and modelling of local microstructure and strength

VPPA welds of Al-2024 alloys: Analysis and modelling of local microstructure and strength

Activation energy determination for linear heating experiments: deviations due to neglecting the low temperature end of the temperature integral

Relations between microstructure, precipitation, age-formability and damage tolerance of Al–Cu–Mg–Li (Mn, Zr, Sc) alloys for age forming

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