The effect of coarse second-phase particles on the rate of grain refinement during severe deformation processing

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

doi:10.1016/s1359-6454(03)00086-7

Cited by 239 publications

(165 citation statements)

References 24 publications

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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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Section: Resultsmentioning

confidence: 74%

Microstructural evolution of AA7050 al alloy processed by ECAP

et al. 2010

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“…[10][11][12][13] On the other hand some of the researchers focused the rapid cooling rate and severe deformation effects on the different Al-Fe alloys. [14][15][16] M. Aghaie-Khafri and R. Mahmudi 17 have investigated the plastic instability and necking behavior of AA8079 aluminum alloy sheet in temper-annealed and fully annealed conditions.…”

Section: Introductionmentioning

confidence: 99%

Analysis of twin-roll casting AA8079 alloy 6.35-μm foil rolling process

Can¹,

Arıkan²,

Çinar³

2016

Mater. Tehnol.

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In this work the rolling process and properties of a 6.35-μm twin-roll casting AA8079 aluminum alloy foil was analyzed. First, the 8-mm-thick sheets were produced with a twin-roll casting technology. This product was annealed and cold rolled to a 6.35-μm foil with suitable processing conditions. The mechanical tests and microhardness measurement was applied to specimens derived from all the foil-rolling process stages. On the other hand, the specimens' surface roughness and the surface structure are visualized with an atomic force microscope and an SEM. The microstructural investigation is realized with an optical microscope and XRD. The von-Misses total effective strain was calculated by determining the incremental work for all of the cold-rolling cycle. The alloy showed very low ductility in the tensile tests because of the second-phase metastable intermetallic particles such as Al3Fe. The maximum elongation at the breaking value was measured for 256-μm-foil as 4.5 %. On the other hand, the alloy did not show any significant strain hardening after the cold rolling during the plastic-deformation stages. Keywords: aluminum foil, cold rolling, twin roll casting V delu je bil analiziran postopek valjanja in latnosti 6,35 folije iz AA8079 aluminijeve zlitine, ulite med dvema valjema. Najprej je bil izdelan 8 mm debel trak po postopku ulivanja med dvema valjema. Trak je bil primerno`arjen in hladno zvaljan v 6.35 μm folijo. Iz vseh stopenj procesa valjanja so bili vzeti vzorci na katerih so bile dolo~ene mehanske lastnosti in izmerjena mikro trdota. Poleg tega je bila hrapavost povr{ine in struktura povr{ine vizualizirana z mikroskopom na atomsko silo (AFM) in iz SEM. Preiskava mikrostrukture je bila izvr{ena s svetlobnim mikroskopom in z rentgensko difrakcijo (XRD). Za dolo~anje stopnjujo~ega dela, med celotnim ciklom hladnega valjanja, je bila izra~unana celotna von-Misses efektivna napetost. Zlitina je pokazala zelo nizko duktilnost pri nateznih preizkusih zaradi vsebnosti delcev sekundarne metastabilne intermetalne faze Al3Fe. Maksimalni raztezek pri poru{itvi je bil pri 256 μm debeli foliji 4.5 %. Po drugi plati pa zlitina ni kazala nobenega ob~utnega napetostnega utrjevanja med posameznimi fazami plasti~ne deformacije. Klju~ne besede: aluminijeva folija, hladno valjanje, ulivanje med dvema valjema

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“…Automated EBSD has therefore become the ideal technique for concurrent access to both the spatial distribution of the grain size and the crystallographic orientation in oxide scales [16], which in turn permits correlations to be made between the two. Texture measurements can hence also be linked to grain size, such as the effect of second-phase particles on the rate of grain refinement in an aluminium alloy [17]. However, the link between grain size and texture evolution in the tertiary oxide scale formed on hot-rolled steel is still unknown.…”

Section: Introductionmentioning

confidence: 99%

Dependence of texture development on the grain size of tertiary oxide scales formed on a microalloyed steel

Jiang

Zhao

et al. 2015

Surface and Coatings Technology

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Q. (2015). Dependence of texture development on the grain size of tertiary oxide scales formed on a microalloyed steel. Surface and Coatings Technology, Dependence of texture development on the grain size of tertiary oxide scales formed on a microalloyed steel AbstractBoth orientational and geometrical characteristics of grains in tertiary oxide scales have been quantitatively investigated using the electron backscatter diffraction (EBSD) technique. Phase and orientation mappings demonstrate that the {001} planes of magnetite and the {0001} planes of hematite are parallel to the direction of oxide growth. Pole figures (PFs) as scattering plots clearly display the direct correlation between the orientations and microstructure sites of magnetite grains. Magnetite grains develop a strong rotated cube texture component that shifts to the {100} component, whereas those with the grain size of 1-5. μm develop the {001} cube texture component. The refined magnetite grains surrounding the abnormal ones can be a combined process, including magnetite pro-eutectoid during hot rolling and cooling and re-oxidation during air-cooling. Our findings offer insights toward further understanding of the link between the geometrical and orientation parameters of grains with respect to the deformation behaviour of oxide scales formed at elevated temperatures.

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The effect of coarse second-phase particles on the rate of grain refinement during severe deformation processing

Cited by 239 publications

References 24 publications

Microstructural evolution of AA7050 al alloy processed by ECAP

Microstructural evolution of AA7050 al alloy processed by ECAP

Analysis of twin-roll casting AA8079 alloy 6.35-μm foil rolling process

Dependence of texture development on the grain size of tertiary oxide scales formed on a microalloyed steel

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