Material modelling data for superplastic forming optimisation

Ridley, N.; Bate, Pete S.; Zhang, B.

doi:10.1016/j.msea.2005.08.108

Cited by 22 publications

(21 citation statements)

References 19 publications

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“…In a number of works, DGG rate was well described and modelled using equations similar to the following (Ridley et al ., 2005; Bate, 2007): where D is the mean grain diameter, is the strain rate and is the grain growth coefficient. The index q is attributed to the effect of second‐phase particles and will be less than 1 if the particles coarsen with time.…”

Section: Resultsmentioning

confidence: 99%

“…In practice, most superplastic materials show a sigmoidal variation of the flow stress with strain rate, and a value of m > 0.3 corresponds to alloys that give superplastic properties. Perturbed‐rate tests (±10% variation of the nominal strain rate), carried out to calculate m (Ridley et al ., 2005), showed that the Al‐4wt%Cu is not a superplastic material ( m approximately 0.22), whereas the Al‐33wt%Cu proved to be an alloy that with certain testing conditions gives superplastic properties ( m approximately 0.6–0.8).…”

Section: Introductionmentioning

confidence: 99%

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Study of dynamic grain growth by electron microscopy and EBSD

Rofman

Bate

Brough

et al. 2009

Journal of Microscopy

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SummaryThe effect of hot deformation on fully recrystallized aluminium-copper alloys (Al-4wt%Cu and Al-33wt%Cu) with different volume fractions of CuAl 2 has been studied. The alloys are Zener pinned systems with different superplastic properties. Strain-induced grain growth, observed in both alloys, was quantitatively estimated by means of electron microscopy and EBSD and compared with the rate of static grain growth. Surface marker observations and in situ hotdeformation experiments combined with EBSD were aimed at clarifying the mechanisms responsible for the changes in the deformed microstructures. A sequence of secondary and backscattered electron images and EBSD maps was obtained during in situ SEM deformation with different testing conditions. Overlaying EBSD maps for the Al-4wt%Cu with channelling contrast images showed that grain boundary motion occurred during deformation, creating a layered structure and leading to an increase in size of some grains and shrinkage of others. Of a particular interest are results related to behaviour of CuAl 2 in superplastic Al-33wt%Cu during deformation, including several problems with the use of EBSD in this alloy.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Study of dynamic grain growth by electron microscopy and EBSD

Rofman

Bate

Brough

et al. 2009

Journal of Microscopy

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“…It can be found that, whether for the objective function build on the thickness values the final error was very small (Q s value less than 1 %), the Q h did not go under a value of 6.6 %. This was considered as a direct consequence of the constitutive equation used to represent the material behaviour, where C and m values were constant even if it was demonstrated that, especially, for 5XXX aluminium alloys it's a too strong approximation [20]. This will showed also in the next section where a constitutive model with a variable m is described.…”

Section: Inverse Analysis For Materials Constants Estimationmentioning

confidence: 99%

Characterization of a superplastic aluminium alloy ALNOVI-U through free inflation tests and inverse analysis

Sorgente

Tricarico

2012

Int J Mater Form

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Numerical methods are widespread in forming applications since a deeper understanding and a finer calibration of the process can be reached without most of the assumptions used in analytical approaches. In this calibration procedure the characterization of the material behaviour is an important preliminary step that cannot be avoided. Experimental tests can be numerically modelled and material constants can be found by inverse methods making numerical results as close as possible to experimental ones. In this work material parameters of a superplastic aluminium alloy have been found by experimental forming tests and an inverse analysis. Constant pressure free inflation tests were firstly performed to find the optimal range for temperature and strain rate values. Material constants were then calculated, on the basis of these tests, minimizing errors between experimental and numerical data through a gradient based optimization iterative procedure. Constant strain rate experimental tests were finally used to refine material parameters and to gain a better agreement between experiments and numerical simulations

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“…This can be done by measuring the elongation to failure in standard tensile tests and the strain rate sensitivity index in jump strain rate tests [9]. Some authors have demonstrated that, when grain boundary sliding (GBS) is the predominant deformation mechanism, the stress and strain condition has a marginal role in the material characterization [10].…”

Section: Materials Characterizationmentioning

confidence: 99%

Blow forming of AZ31 magnesium alloy at elevated temperatures

et al. 2009

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In this work, the forming behaviour of a commercial sheet of AZ31B magnesium alloy at elevated temperatures is investigated and reported. The experimental activity is performed in two phases. The first phase consists in free bulging test and the second one in analysing the ability of the sheet in filling a closed die. Different pressure and temperature levels are applied. In free bulging tests, the specimen dome height is used as characterizing parameter; in the same test, the strain rate sensitivity index is calculated using an analytical approach. Thus, appropriate forming parameters, such as temperature and pressure, are individuated and used for subsequent forming tests. In the second phase, forming tests in closed die with a prismatic shape cavity are performed. The influence of relevant process parameters concerning forming results in terms of cavity filling, fillet radii on the final specimen profile are analysed. Closed die forming tests put in evidence how the examined commercial magnesium sheet can successfully be formed in complicated geometries if process parameters are adequately chosen

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Material modelling data for superplastic forming optimisation

Cited by 22 publications

References 19 publications

Study of dynamic grain growth by electron microscopy and EBSD

Study of dynamic grain growth by electron microscopy and EBSD

Characterization of a superplastic aluminium alloy ALNOVI-U through free inflation tests and inverse analysis

Blow forming of AZ31 magnesium alloy at elevated temperatures

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