Ultra-fine grain structures in aluminium alloys by severe deformation processing

Prangnell, P.B.; Bowen, Jacob R.; Apps, P.J.

doi:10.1016/j.msea.2003.10.170

Cited by 194 publications

(124 citation statements)

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“…These considerably inhibit AZ91's widespread application. Some research focused on grain refinement of AZ91 using severe plastic deformation (SPD) techniques, [1][2][3] including equal channel angular pressing (ECAC) 4,5 and accumulative roll bonding (ARB), [6][7][8] which can improve both the strength and ductility. Nevertheless, SPD techniques have difficulty satisfying industrial needs due to their low production efficiency and high manufacturing cost.…”

Section: Introductionmentioning

confidence: 99%

Improved ductility of aged Mg-9Al-1Zn alloy strip by electropulsing treatment

et al. 2009

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The effect of electropulsing treatment (EPT) on the microstructure and mechanical properties of aged Mg-9Al-1Zn alloy strip was studied. EPT was found to accelerate tremendously the b phase spheroidization in the aged Mg-9Al-1Zn alloy. This improved microstructure exhibits excellent mechanical properties, that is, increasing elongation to failure significantly without loss of tensile strength. The spheroidization of the b phase during EPT was attributed to the reduction of the nucleation thermodynamic barrier and enhancement of atomic diffusion.

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Section: Introductionmentioning

confidence: 99%

Improved ductility of aged Mg-9Al-1Zn alloy strip by electropulsing treatment

et al. 2009

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“…Deformations bands can be observed in the interior of some grains. As it has been previously reported [17,18], deformation bands develop because it is energetically easier for a constrained grain to deform by splitting into bands (or cell blocks) that deform on fewer than the five slip systems required for homogeneous deformation. The formation of new high angle grain boundaries induced by deformation can occur if the disorientations between the deformation bands increase sufficiently.…”

Section: Resultsmentioning

confidence: 74%

Microstructural evolution of AA7050 al alloy processed by ECAP

et al. 2010

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This work aimed to study the microstructural evolution of commercial aluminum alloy AA7050 in the solution treated condition (W) processed by equal channel angular pressing -ECAP. The analyses were made considering the effects of process parameters as temperature (T amb and 150°C), processing route (A and B C ) and number of passes. Optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used for microstructural characterization, and hardness tests for a preliminary assessment of mechanical properties. The results show that the refining of the microstructure by ECAP occurred by the formation of deformation bands, with the formation of dislocations cells and subgrains within these bands. The increase of the ECAP temperature led to the formation of more defined subgrains contours and intense precipitation of η phase in the form of spherical particles. The samples processed by Route B C present a more refined microstructure.Keywords: aluminum alloy; ECAP; microstructure. INTRODUCTIONSevere plastic deformation (SPD) techniques have been widely used for the production of ultra fined grained microstructures in metal and alloys [1][2]. Among the various SPD processes available, equal channel angular pressing, ECAP is especially attractive because it is the most cost effective and easiest way due to the simplicity of process and tooling and because it can be scale-up to produce bulk ultra fined grained materials for structural applications. The process allows materials to undergo severe shearing deformation and break up the original texture into ultrafined or nanostructure after a number of passes of pressing through a die composed by two channels that intersect in an angle usually of 90° or 120° [1][2][3][4]. The process imposes a high strain on the sample so that a high dislocation density is introduced. These dislocations re-arrange during the multiple passes of ECAP to form subgrains and subsequently new high angle grain boundaries.Investigation of ECAP processing of precipitation-hardened Al alloys was primary focused on the process refinement [5][6][7][8] and more recently on the evolution and controlling of precipitation microstructure [9][10][11][12][13]. Previous studies [4,14] have reported that different microstructures can be obtained in Al and Al alloys dependent upon the ECAP route. Gholinia et al [5] have demonstrated that during deformation with a constant strain path the grains in the alloy subdivide by the buildup of disorientations between cell blocks as the strain increases. This leads to the formation of elongated subgrains. When a billet is processed with a clockwise and anticlockwise 90° rotation, between each alternate pressing, this results in the continual buildup of shear on two mutually orthogonal planes. This is the less efficient route to produce submicron grains [5]. With a 90° rotation in the same direction, the billet is again sheared in two mutually orthogonal planes, but despite the redundant nature of the total strain, this p...

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“…Severe deformation (greater than a true strain of about 4), is not possible during standard metalworking processes, except for processes yielding thin gage material [12]. Cyclic strain methods, e.g.…”

Section: Comparison Of Accomplishments With the Goals And Objectives mentioning

confidence: 99%

“…in rolling of sheet metal to thin foil [12]. High strains can be imparted to large workpieces by cyclic methods, including equal channel angular extrusion (ECAE), torsion, or cyclic-multiaxial forging.…”

Section: Task 1 Selection Of Ecae Die Geometrymentioning

confidence: 99%

“…The final requirement has been found to be important in severe strain processing, and metals and alloys with more than a 30% area fraction of low-angle grain boundaries (with angles < 10 °) are not stable and likely to undergo anomalous grain growth during annealing. The low angle boundaries are a potent force for coarsening [12]. The microstructures which remain stable after the recrystallization anneal are more likely to retain a fine structure during the subsequent extrusion processes, which are performed at an elevated, but lower temperature than the recrystallization temperature (although with applied strain).…”

Section: Final Report Sbir De-fg02-04er83909mentioning

confidence: 99%

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Production of Seamless Superconducting Radio Frequency Cavities from Ultra-fine Grained Niobium, Phase II Final Report

Crooks¹

2009

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Ultra-fine grain structures in aluminium alloys by severe deformation processing

Cited by 194 publications

References 19 publications

Improved ductility of aged Mg-9Al-1Zn alloy strip by electropulsing treatment

Improved ductility of aged Mg-9Al-1Zn alloy strip by electropulsing treatment

Microstructural evolution of AA7050 al alloy processed by ECAP

Production of Seamless Superconducting Radio Frequency Cavities from Ultra-fine Grained Niobium, Phase II Final Report

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