Evaluating plastic anisotropy in two aluminum alloys processed by equal-channel angular pressing

Xu, Cheng; Száraz, Zoltán; Trojanová, Zuzanka; Lukáč, P.; Langdon, Terence G.

doi:10.1016/j.msea.2008.06.045

Cited by 44 publications

(24 citation statements)

References 45 publications

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“…Figure 8 shows the results of tests conducted to evaluate the extent of any plastic anisotropy by testing compression samples of (a) Al- Using Severe Plastic Deformation for the Processing of Advanced Engineering Materials 1617 6061 and (b) Al-7034 under the same conditions at 298 K but using samples pressed through 6 passes in ECAP and then cut with orientations in the X, Y or Z directions. 51) Inspection of these two sets of curves shows there is no significant plastic anisotropy in either alloy after processing by ECAP and it is reasonable to conclude there is an overall homogeneity throughout both materials.…”

Section: Mechanical Properties At Low Temperaturesmentioning

confidence: 92%

Using Severe Plastic Deformation for the Processing of Advanced Engineering Materials

Figueiredo

Langdon

2009

Mater. Trans.

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The processing of metals through the application of severe plastic deformation leads to significant grain refinement and provides an opportunity for achieving superior properties. The two procedures of equal-channel angular pressing (ECAP) and high-pressure torsion (HPT) are examined with emphasis on the mechanical properties at low and high temperatures and the nature of the grain refinement. It is demonstrated that grain refinement occurs relatively homogeneously in f.c.c metals through the formation of dislocation cells or subgrains and the evolution of these cells into an array of ultrafine grains separated by high angle boundaries. By contrast, grain refinement in h.c.p. metals such as magnesium is inhomogeneous and occurs through the nucleation of new grains along the initial grain boundaries due to the high stresses generated to activate multiple slip systems. Ultrafine-grained metals generally exhibit high strength but they may exhibit weakening if the processing conditions adversely affect the precipitate morphology. If the ultrafine grains are stable at high temperatures there is a possibility of achieving excellent superplastic properties.

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Section: Mechanical Properties At Low Temperaturesmentioning

confidence: 92%

Using Severe Plastic Deformation for the Processing of Advanced Engineering Materials

Figueiredo

Langdon

2009

Mater. Trans.

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“…11 is for the as-received unprocessed alloy and the lower curves are for samples processed through 1, 2 and 6 passes of ECAP: the designation Z direction refers to cutting the samples perpendicular to the flow direction and perpendicular to the upper surface of the ECAP billet. [134] Figure 11 shows also that there is a lower rate of strain hardening after yielding when processing by ECAP.…”

Section: Weakening By Spdmentioning

confidence: 93%

“…Stress-strain curves for Al-7034 showing the weakening through increasing numbers of ECAP passes. [134] Figure 12. Weakening in Zn-22% Al with increasing numbers of HPT turns.…”

Section: Figure Captionsmentioning

confidence: 99%

The Strength–Grain Size Relationship in Ultrafine-Grained Metals

Balasubramanian

Langdon

2016

Metall Mater Trans A

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Metals processed by severe plastic deformation [SPD] techniques, such as equal-channel angular pressing [ECAP] and high-pressure torsion [HPT], generally have submicrometer grain sizes. Consequently, they exhibit high strength as expected on the basis of the HallPetch [H-P] relationship. Examples of this behavior are discussed using data on Ti, Al-Mg 1 and Ni. These materials typically have grain size above ~50 nm where softening is not expected. An increase in strength is usually accompanied by a decrease in ductility. High strength and ductility can be achieved simultaneously by imposing high strains to give both ultrafine grain sizes and a high fraction of high-angle grain boundaries. An example is presented for a cast Al-7% Si alloy processed by HPT. In some cases, SPD may produce a fine grain size but also lead to a weakening due to microstructural changes as in ECAP of an Al-7034 alloy and HPT of Zn-22% Al. In SPD-processed materials, grain boundary segregation and nanostructural features are present which may lead to higher strengths than those predicted by the H-P relationship in some alloys having nano grain sizes.

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“…Ultrafine-grained (UFG) materials typically exhibit average grain sizes in the range of 100 nm to 1 µm. Compared to their conventional, coarse-grained counterparts, these materials often exhibit a significantly increased strength [1][2][3][4]. The majority of previous investigations have been done on materials processed by ECAP in laboratory scale.…”

Section: Introductionmentioning

confidence: 99%

Microstructural Features and Mechanical Properties after Industrial Scale ECAP of an Al 6060 Alloy

Frint

Hockauf

Halle

et al. 2010

MSF

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Future applications of ultrafine-grained, high performance materials produced by equalchannel angular pressing (ECAP) will most likely require processing on an industrial scale. There is a need for detailed microstructural and mechanical characterisation of large-scale, ECAP-processed billets. In the present study, we examine the microstructure and mechanical properties as a function of location and orientation within large (50 x 50 x 300 mm³) billets of an Al-6060 alloy produced by ECAP (90° channel angle) with different magnitudes of backpressure. The internal deformation is analysed using a grid-line method on split billets. Hardness is recorded in longitudinal and crosssectional planes. In order to further characterise the local, post-ECAP mechanical properties, tensile tests in different layers are performed. Moreover, low-voltage scanning transmission electron microscopy observations highlight relevant microstructural features. We find that the homogeneity and anisotropy of mechanical properties within the billets depend significantly on the geometry of the shear zone. We demonstrate that deformation gradients can be reduced considerably by increasing the backpressure: The opening-angle of the fan-shaped shear zone is reduced from ψ ≈ 20 ° to ψ ≈ 7 ° when the backpressure is increased from 0 to 150 MPa. Backpressures of 150 MPa result in excellent homogeneity, with a relative variation of tensile mechanical properties of less than 7 %. Our investigation demonstrates that ECAP is suitable for processing homogenous, high performance materials on a large scale, paving the way for advanced industrial applications.

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Evaluating plastic anisotropy in two aluminum alloys processed by equal-channel angular pressing

Cited by 44 publications

References 45 publications

Using Severe Plastic Deformation for the Processing of Advanced Engineering Materials

Using Severe Plastic Deformation for the Processing of Advanced Engineering Materials

The Strength–Grain Size Relationship in Ultrafine-Grained Metals

Microstructural Features and Mechanical Properties after Industrial Scale ECAP of an Al 6060 Alloy

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