Constitutive equations for high temperature flow stress of aluminium alloys

Shi, Hang; McLaren, A. J.; Sellars, C. M.; Shahani, Ravi; Bolingbroke, R.K.

doi:10.1179/mst.1997.13.3.210

Cited by 172 publications

(73 citation statements)

References 6 publications

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“…These relationships model a viscoplastic behaviour linking the flow stress with temperature, strain and strain rate. The values of the parameters used in the above formulae (A 1 , A 2 , B 1 , B 2 , C 1 , C 2 , n 0 , n ss , m, Q def ) were fitted to stress/strain data obtained through hot plane strain compression tests [13] The roll was modelled as steel working within its elastic response. Table 3 shows the physical constants used in the model for both roll and slab.…”

Section: Methodsmentioning

confidence: 99%

Measurement of Deformation Gradients in Hot Rolling of AA3004

Boldetti

2005

Experimental Mechanics

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In this paper we describe an experimental technique developed to measure the deformation gradients and temperature in a single hot rolling pass of an AA3004 sample that was fitted with an insert. The insert had been previously hand engraved with a 1x1 mm grid pitch and the analysis of the data digitally captured from the image of the deformed grid enabled the calculation of the components of the deformation gradient tensor. Four steel pins prevented relative motion between the insert and the rest of the sample. No detachment was observed between insert and sample after rolling. The temperature was measured during rolling using two embedded thermocouples, one close to the surface and the other in the centreline. The commercial finite element code ABAQUS was used to create a three-dimensional model of the rolling process. The recorded temperature was compared to the numerical values evaluated after tuning the heat transfer coefficient. The shape of the grid after rolling was checked against the deformed mesh using different friction coefficients in order to obtain the optimum match. The unusually large length of the insert enabled the rolling process to be stopped halfway so that a picture of the rollgap area could be obtained. This provided a partially deformed grid that represented the transient state during rolling. The experimentally determined deformation gradient in this area as well as in the steady state area agreed well with the finite-element predictions.

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Section: Methodsmentioning

confidence: 99%

Measurement of Deformation Gradients in Hot Rolling of AA3004

Boldetti

2005

Experimental Mechanics

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“…According to Jonas et al [14], Huang et al [15], and Shi et al [16], the strain rate ( . ε) can be expressed as a function of flow stress (σ) by Equation (3) .…”

Section: Governing Equationsmentioning

confidence: 98%

“…According to Jonas et al [14], Huang et al [15], and Shi et al [16], it is assumed that the relationship between σ P and . ε N at temperatures 673-723 K and 773-823 K follows Equations (4) and (3), respectively.…”

Section: Identification Of Parametersmentioning

confidence: 99%

Effect of Fe-Content on the Mechanical Properties of Recycled Al Alloys during Hot Compression

Hou

et al. 2017

Metals

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Abstract:It is unavoidable that Fe impurities will be mixed into Al alloys during recycling of automotive aluminum parts, and the Fe content has a significant effect on the mechanical properties of the recycled Al alloys. In this work, hot compression tests of two Fe-containing Al alloys were carried out at elevated temperatures within a wide strain rate range from 0.01 s −1 to 10 s −1 . The effect of Fe content on the peak stress of the stress vs. strain curves, strain rate sensitivity and activation energy for dynamic recrystallization are analyzed. Results show that the recycled Al alloy containing 0.5 wt % Fe exhibits higher peak stresses and larger activation energy than the recycled Al alloy containing 0.1 wt % Fe, which results from the fact that there are more dispersed AlMgFeSi and/or AlFeSi precipitates in the recycled Al alloy containing 0.5 wt % Fe as confirmed by SEM observation and energy spectrum analysis. It is also shown that the Fe content has little effect on the strain rate sensitivity of the recycled Al alloys.

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“…The maximum applicable stress values define a minimum stressor layer thickness that we have to ensure for a successful exfoliation process. As the flow stress strongly depends on temperature and strain rate 34,35 the values from the XRD measurement might not be the correct absolute stress values to define a hard limit. However, the thinnest high-purity Al layer that we could use for a successful exfoliation process had a thickness of 100 lm, in accordance with the graph in Fig.…”

Section: B Minimum Al Layer Thickness For Exfoliationmentioning

confidence: 99%

“…Besides the material composition, the hardening coefficient H Al also depends on the absolute processing temperature and the cooling rate. 34 If it is not possible to avoid temperatures during processing that would lead to interface debonding, the introduction of a textured Al-Si interface would be an option to expand the processing limits, as the critical energy release rate for debonding scales with the area of the interface. Hence, our results imply that MEMO-layers are wellsuited for low-temperature solar cell processing up to at least 210°C, depending on the particular properties of the Al layer, and are thus compatible with the proposed module level processing concept.…”

Section: B Mechanical Stability Of Memo Bilayersmentioning

confidence: 99%

Kerfless exfoliated thin crystalline Si wafers with Al metallization layers for solar cells

et al. 2015

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We report on a kerfless exfoliation approach to further reduce the costs of crystalline silicon photovoltaics making use of evaporated Al as a double functional layer. The Al serves as the stress inducing element to drive the exfoliation process and can be maintained as a rear contacting layer in the solar cell after exfoliation. The 50-70 lm thick exfoliated Si layers show effective minority carrier lifetimes around 180 ls with diffusion lengths of 10 times the layer thickness. We analyze the thermo-mechanical properties of the Al layer by x-ray diffraction analysis and investigate its influence on the exfoliation process. We evaluate the approach for the implementation into solar cell production by determining processing limits and estimating cost advantages of a possible solar cell design route. The Al-Si bilayers are mechanically stable under processing conditions and exhibit a moderate cost savings potential of 3-36% compared to other c-Si cell concepts.

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Constitutive equations for high temperature flow stress of aluminium alloys

Cited by 172 publications

References 6 publications

Measurement of Deformation Gradients in Hot Rolling of AA3004

Measurement of Deformation Gradients in Hot Rolling of AA3004

Effect of Fe-Content on the Mechanical Properties of Recycled Al Alloys during Hot Compression

Kerfless exfoliated thin crystalline Si wafers with Al metallization layers for solar cells

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