Constitutive modelling of primary creep for age forming an aluminium alloy

Ho, Kar; Lin, Jianguo; Dean, Trevor

doi:10.1016/j.jmatprotec.2004.04.304

Cited by 104 publications

(69 citation statements)

References 17 publications

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“…The creep-ageing test procedure used by Ho et al [4] was adopted and the tests were carried out at 115 o C under four tensile stress levels: 200, 240, 260 and 280 MPa. Room temperature tensile tests were carried out on selected creep-aged specimens.…”

Section: Materials Testingmentioning

confidence: 99%

“…As current deformation of a metallic alloy also depends on its microstructure, which changes dynamically during CAF, accurate prediction of formed part quality cannot be achieved solely using conventional viscoplastic creep equations. Attention has been drawn towards developing mechanism-based creep-ageing constitutive equations that consider evolutions of microstructure and mechanical properties, and efforts have been made towards the concurrent modelling of both the shaping and material processing functions of CAF as a result [3,4].…”

Section: Introductionmentioning

confidence: 99%

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Material modelling for creep-age forming of aluminium alloy 7B04

Lam

Shi

Huang

et al. 2015

MATEC Web of Conferences

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Abstract. This paper presents a study on the creep-ageing behaviour of a peak-aged aluminium alloy 7B04 under different tensile loads at 115 o C and subsequently modelling it for creep-age forming (CAF) applications. Mechanical properties and microstructural evolutions of creep-aged specimens were investigated. The material was modelled using a set of unified constitutive equations, which not only captures the material's creep deformation but also takes into account yield strength contributions from solid solution hardening, age hardening and dislocation hardening during creep-ageing. A possible application of the present work is demonstrated by implementing the determined material model into a commercial finite element analysis solver via a user-defined subroutine for springback prediction of creep-age formed plates. A good agreement is observed between the simulated springback values and experimental results. This material model now enables further investigations of 7B04 under various CAF scenarios to be conducted inexpensively via computational modelling.

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Section: Materials Testingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Material modelling for creep-age forming of aluminium alloy 7B04

Lam

Shi

Huang

et al. 2015

MATEC Web of Conferences

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“…Many constitutive models for CAF have been developed to predict the mechanical properties and form shape so that a specific strength and part shape can be achieved [10,11]. Zhan et al [12] proposed a set of mechanism-based unified creep-aging constitutive equations to model creep deformation and the evolutions of precipitate size and dislocation density, which control the amount of age hardening, solid solution hardening and work hardening during creep-ageing.…”

Section: Introductionmentioning

confidence: 99%

Constitutive modelling of creep-ageing behaviour of peak-aged aluminium alloy 7050

Yang

Lam

Shi

et al. 2015

MATEC Web of Conferences

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Abstract. The creep-ageing behaviour of a peak-aged aluminium alloy 7050 was investigated under different stress levels at 174• C for up to 8 h. Interrupted creep tests and tensile tests were performed to investigate the influences of creep-ageing time and applied stress on yield strength. The mechanical testing results indicate that the material exhibits an over-ageing behaviour which increases with the applied stress level during creep-ageing. As creep-ageing time approaches 8 h, the material's yield strength under different stress levels gradually converge, which suggests that the difference in mechanical properties under different stress conditions can be minimised. This feature can be advantageous in creep-age forming to the formed components such that uniformed mechanical properties across part area can be achieved. A set of constitutive equations was calibrated using the mechanical test results and the alloy-specific material constants were obtained. A good agreement is observed between the experimental and calibrated results.

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“…In age forming of aluminium alloys for airframe applications, curved wing skin components are manufactured by mechanically conforming a plate or sheet over a specially designed curved tool, with the metal and tool combination then being held (under load) at the alloy's ageing temperature to simultaneously achieve precipitation in the alloy and creep relaxation of the material into the required curvature [1,2]. After release of the load springback will occur, which can be substantial.…”

Section: Introductionmentioning

confidence: 99%

“…The main challenge for application in these and other damage tolerant parts lies in obtaining the best balance between the often conflicting sets of requirements such as creep rate during age forming and fatigue crack growth resistance of the age formed product. A limited number of works have been published which focus on the principles of this relatively new processing technique [1,2] and on application to selected standard aerospace Al based alloys [3,4]. However, no reports on the main mechanisms responsible for the relations between composition, formability and resulting properties have been published, and no methodologies for optimising the combination of alloys and process with respect to damage tolerant properties have been published.…”

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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Constitutive modelling of primary creep for age forming an aluminium alloy

Cited by 104 publications

References 17 publications

Material modelling for creep-age forming of aluminium alloy 7B04

Material modelling for creep-age forming of aluminium alloy 7B04

Constitutive modelling of creep-ageing behaviour of peak-aged aluminium alloy 7050

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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