Strong Cube Texture Research Articles

A comparative study of clock rolling and unidirectional rolling on deformation/recrystallization microstructure and texture of high purity tantalum plates

Clock rolling, which rotates a sample 135° with respect to the previous rolling direction, was used to study the effect of strain path change on deformation and recrystallization microstructure and texture in high purity tantalum plates in the present work. High purity tantalum plates were unidirectional and clock rolled to 87% reduction then annealed at various temperatures. The texture and microstructure in the surface layer of the rolled and annealed plates were characterized using X-ray diffraction (XRD), light microscopy (LM), electron backscatter diffracting (EBSD) and electron channeling contrast imaging (ECCI). The hardness values of the annealed plates were measured using Vickers hardness testing. The results show that the unidirectional- and clock-rolled materials exhibit different textures. The unidirectional rolled plate recrystallized more quickly than that of the clock rolled plate. After annealing at 1200°C, pronounced γ-fiber in the unidirectional rolled plate while strong cube texture mixed with less strong γ-fiber in the clock rolled plate was found. The annealed clock rolled plate had smaller grain size and less variation than that of the annealed unidirectional rolled plate. The change of strain path plays an important role in the recrystallization kinetics and microstructure of high purity tantalum plates.

Additional relaxations in the Alamel texture model

The additional relaxation of the L12 shear components of the velocity gradient has earlier been suggested for the special case of rolling in the Lamel Taylor-type of texture aggregate model. This concept of so called type III of relaxation is here generalized to apply for general strain paths by a modification of the Alamel model. Relaxations are made for arbitrarily oriented grain boundary segments, for which only invariant relaxations are allowed. The Alamel+type III model is compared to other Taylor-like models (FC Taylor, Lamel, Lamel+type III, GIA, VPSC) for the case of cold rolling of an initial random texture, as well as for a strong cube texture. In both cases the new model gives improved texture predictions.

Recrystallization Texture of Heavily Cold Rolled Polycrystalline Nickel Sheets with and without Strong Starting Cube Texture

The evolution of texture is studied in high purity (~99.7%) nickel sheets with widely different starting cube texture ({001}) intensities following heavy cold rolling and annealing. For this purpose two nickel sheets with strong and weak starting recrystallization cube texture (SSCT and WSCT, respectively) prepared by Accumulative Roll Bonding and conventional rolling, respectively, followed by annealing are used as the starting materials for subsequent processing. These sheets are cold rolled to 90% reduction in thickness and annealed at different temperatures. Profuse cube oriented bands could be identified in the SSCT nickel sheet after 90% cold rolling as opposed to rather insignificant presence of cube regions in the WSCT nickel sheet. However, the WSCT nickel sheets consistently show stronger cube texture after annealing treatments as compared to the SSCT material. The failure to observe recrystallization cube texture in SSCT is attributed to the inhibited nucleation of cube grains owing to the unfavorable misorientation environment surrounding cube regions in the deformed matrix.

Effects of Driving Force and Boundary Migration Velocity on Formation of Recrystallization Texture in Cold Rolled Pure Aluminum Sheets

The effects of net driving force for migration of high angle grain boundaries were emphasized beside many other factors which could influence the process of texture formation during recrystallization annealing of 95% cold rolled pure aluminum sheets. The net driving force consists basically of stored energy. However, it could be reduced by recovery, boundary drag, solute drag and Zener drag in different extents, in which only boundary drag is mis-orientation dependent. It was indicated that both oriented nucleation and oriented growth have obvious influence on recrystallization texture, and how far they influence the texture depends also on the level of net driving force when the grain growth starts during annealing. Oriented growth, which is induced by the differences in boundary drag of differently oriented grains, and the corresponding texture formation, could be observed easily when the recrystallization proceeds under relative higher solute drag and Zener drag in commercial purity aluminum. The oriented nucleation process prevails during recrystallization of sufficiently recovered high purity aluminum with very low solute drag and Zener drag, after which strong cube texture forms. In this case the oriented growth indicates limited effect. Both the oriented growth and oriented nucleation will fail if high purity deformation matrix without clear solute drag and Zener drag has not experienced an obvious recovery before recrystallization grain growth, since extremely high net driving force leads to very small critical nucleus size and multiplicity of growing grains, which results in randomization of recrystallization texture.

Annealing behaviour of a nanostructured Cu–45 at.%Ni alloy

The microstructure and crystallographic texture have been investigated in a Cu–45 at.%Ni alloy after heavy rolling and subsequent annealing at different temperatures. Cold-rolling to a von Mises strain of 5.7 produced a sample with an average boundary spacing along the normal direction of ~70 nm and a large fraction of high-angle boundaries (HABs), ~70 %. Annealing of this sample for 1 h at temperatures ≤450 °C causes structural coarsening, during which the fraction of HABs decreases. Annealing at higher temperatures results in pronounced discontinuous recrystallization accompanied by twinning. Large frequencies of twin boundaries contribute to high HAB fractions measured in the as-recrystallized condition. Cube-oriented grains demonstrate a size advantage compared to grains of other orientations, thus creating a strong cube texture in the recrystallized material. Further annealing of the recrystallized microstructure promotes grain growth, which leads to a significant strengthening of the cube texture and to a dramatic loss of HABs. After 1 h of annealing at 1000 °C the fraction of the cube texture reaches 99 % and the HAB fraction is 12 %.

Effect of the Heat Treatment on the Cube Recrystallization Texture of Al-Mn-Mg Aluminum Alloy

The evolution of the recrystallized structure and texture of a cold-rolled Al-Mn-Mg alloy with different heat treatments was studied. The alloy with dual-heat treatments at 872 K and 644 K (599 °C and 371 °C) exhibited fast recrystallization and had coarser recrystallized grains and stronger cube texture than the alloy with single-heat treatment at 872 K (599 °C). The differences in microstructures and textures were attributed to the precipitation state. Large particles formed during annealing at 872 K (599 °C) played a randomizing effect on the total recrystallization texture, while smaller particles formed during annealing at 644 K (371 °C) not only enhanced recrystallization of the cold-rolled sheets, but also caused formation of coarse, recrystallized grains with a strong cube texture. The evolution of the coarse grains was due to nucleation of cube-oriented grains.

Preparation and Characterization of Cube-Textured Ni-5 at.% W Substrates for Coated Conductors

The goal of present study was to manufacture and characterize the Ni-5 at.% W alloy substrates for coated conductor applications with a strong cube texture. Cube-textured Ni-5 at.% W alloy substrates were fabricated by heavy cold rolling (98%) and a high temperature annealing (1200°C). From the EBSD and XRD analysis of the fully recrystallized tapes, the cube texture component in the tape was found to reach a proportion as high as 99.5% within a tolerance angle of less than 9o, while the FWHM (full width at half maximum) values of the out-of-plane and in-plane textures are about 5.8o and 6.9o, respectively. Moreover, the grain size distribution is homogeneous, and there is a large amount of low angle grain boundaries (95.6%). This process is very suitable for preparation of substrates for coated conductors.

Effect of Pre-Recovery on Recrystallization Texture in Nickel Substrates for Coated Conductors

Electron backscattered diffraction (EBSD) technology was applied to study the effect of pre-recovery on the recrystallization texture in nickel substrates for coated conductors. Pure nickel (99.999%) was cold rolled by a 95% total reduction, and then samples were annealed at 200 °C for 1 hour and quenched for fully recovery, and finally annealed at 600 °C for 1 hour and quenched in water. The results show that pre-recovery had a strong influence on the formation of cube recrystallization texture. Compared with samples without pre-recovery treatment at 200 °C, samples through pre-recovery treatment can achieve stronger cube texture after recrystallization annealing, and develop more low-angle grain boundaries but less sigma 3 (Σ3) grain boundaries.

Evolution of microstructure, texture and topography during additional annealing of cube-textured Ni–5at.%W substrate for coated conductors

Microstructure, texture and topography have been studied in a recrystallized Ni–5at.%W substrate before and after additional annealing at 1025°C for 1h. The initial recrystallized material contained a strong cube texture and a high fraction of low angle grain boundaries. Σ3 boundaries were also frequent in this substrate, including both coherent and incoherent twin boundary segments as well as non-twin Σ3 boundaries formed between twins and non-matrix neighbors of the cube texture component. A strong correlation between the boundary type and the average depth of grain boundary grooves was observed in this material. The smallest average groove depth was obtained for coherent twin boundaries, followed by low angle boundaries. Significantly greater average groove depths were found for the other boundary types. A similar correlation was also observed between the boundary type and the average inclination angle of groove walls. The additional annealing resulted in grain growth, texture strengthening and an increase in the fraction of low angle boundaries. Also, changes were observed in the extent of thermal grooving studied in the same regions before and after the additional annealing. Groove depths increased for a large number of stationary boundaries, whilst the majority of migrating boundaries developed shallower grooves compared to those before the additional annealing.

Microstructure and texture of Al coating during kinetic spraying and heat treatment

Microstructure and texture formation of an Al coating during kinetic spraying (or cold gas dynamic spraying) and heat treatment were investigated. Coating formation by kinetic spraying is based on super-sonic collision of in-flight micron-sized particles and their severe interfacial plastic deformation under ultra-high strain rates (1.0 × 106–0.5 × 109 s−1), which induces adiabatic shear instability. Shear texture, 45°-rotated Cube {001} , and static recovered microstructure were formed at the interface of Al during kinetic spraying because Al has the equivalent slip system {111} of a face-centered cubic having high stacking fault energy (SFE). During heat treatment, discontinuous recrystallization and grain growth led to transformation of the shear texture into a strong Cube texture, {001} , and misorientation angle transition. Given the mechanical and physical properties of the Al, metallurgical mechanisms of microstructure and texture formation of kinetic-sprayed and heat-treated Al coatings were suggested based on transmission electron microscopy and electron backscatter diffraction analysis.

アルミニウム合金板の深絞り成形における0°/180°耳形成に及ぼす集合組織の影響

It is known in aluminum alloy sheets that two ears on a cup formed by deep drawing in 0° and 180° to the rolling direction may grow up by cold rolling. In the previous reports, Goss and RD rotated cube textures were fingered as the cause of the 0°/180° earing. But the growth process of the 0°/180° earing is not clear. In the present work, texture analysis has been carried out in cold rolling process with AA 6016 aluminum alloy sheets that have a strong cube texture through the thickness and Goss texture at the center layer. RD rotated cube texture is formed at the surface layer by cold rolling whereas cube texture at the center layer decreases rapidly. It is indicated that RD rotated cube texture at the surface layer and persisting Goss texture at the center layer cause high 0°/180° earing. These texture factors are discussed by a crystal plasticity finite element analysis.

Topographic Changes in Ni-5at.%W Substrate After Annealing Under Conditions of Buffer Layer Crystallization

Abstract Topographic changes have been studied in an annealed Ni-5at.%W substrate with a strong cube texture before and after additional annealing reproducing conditions of buffer layer crystallization. It was found that during this additional annealing the microstructure slightly coarsened and that the average depth of grain boundary grooves increased considerably for certain boundary types. Grooves at general high angle boundaries and Σ3 boundaries with large deviations from the ideal twin relationship were found to be more sensitive to the additional heat-treatment than grooves at low angle and true twin boundaries. Average groove widths increased for all boundary types. Despite the observed changes in the extent of grain boundary grooving, the mean surface roughness was almost identical before and after the additional annealing.

Effect of Texture on 0°/180° Earing in Deep Drawing of Aluminum Alloy Sheets

It is known in aluminum alloy sheets that two ears on a cup formed by deep drawing in 0 and 180° to the rolling direction may grow up by cold rolling. In the previous reports, Goss and RD rotated cube textures were fingered as the cause of the 0°/180° earing. But the growth process of the 0°/180° earing is not clear. In the present work, texture analysis has been carried out in cold rolling process with AA 6016 aluminum alloy sheets that have a strong cube texture through the thickness and weak Goss texture at the center layer. RD rotated cube texture is formed at the surface layer by cold rolling whereas cube texture at the center layer decreases rapidly. It is indicated that RD rotated cube texture at the surface layer and persisting Goss texture at the center layer cause high 0°/180° earing. These texture factors are discussed by a crystal plasticity finite element analysis. The calculated earing profiles derived by the finite element analysis show much the same patterns of experimental earing profiles. [doi:10.2320/matertrans.L-M2012825]

Formation and Development of Strong Cube Recrystallization Texture in an Aluminium of Commercial Purity

The goal of the present study inspired by previous works on high purity aluminiun was to manufacture aluminium sheets of commercial purity, grade 1050, with a strong cube texture. In this preliminary work on AA1050, sheets which cube volume fraction reaches 65% have been manufactured. Parameters controlling cube orientation development are mainly the solute dragging due to impurities in solid solution and the stored deformation energy. Besides the 85% cold rolling (CR), two extra annealings and a slight cold rolling are introduced in the processing route to increase the cube volume fraction. The cube orientation, whose substructure is equiaxed, is important for its recovery. It develops thanks to the difference of stored energy relative to that of its first neighbors; the slight cold rolling enhances growth of these cube grains.

Effects of Initial Parameters on the Development of Cube Texture during Recrystallization of Copper

A series of oxygen free high conductivity copper samples with different initial grain sizes, cold rolling conditions and storage times as well as slightly different impurity contents was used to investigate the effects of these initial parameters on the development of cube texture during recrystallization. For rolling reductions of 90% and 95%, cube textures with volume fractions between 3% and 50% were observed. Higher rolling reduction led to a stronger cube texture. Cube texture development is very sensitive to the initial grain size before rolling. In general, fine grained material gives a strong cube texture after recrystallization, and the requirement on fineness of the grain size may vary for materials with different purity. Large sample widening during rolling can largely inhibit the development of cube texture after recrystallization. Neither storage time, nor the slight change in impurity content had large effects in the present investigation.

Comparison of texture evolution between different thickness layers in cold rolled Al–Mg alloy

The texture evolution at different thickness layers in cold rolled AA 5052 aluminum alloy was analyzed quantitatively in terms of a simple relation between the texture volume fractions and true rolling strain. The effect of roll-gap geometry, friction between the roll and sheet and initial through-thickness texture gradient on the texture evolution during rolling was determined. The results show that the roll-gap geometry decreases the rate of texture evolution at the quarter layer in the early stage of deformation. In the case of oil as a lubricant, the very small friction between the roll and sheet slightly decreases the rate of texture evolution at the surface layer. At large strains the low rate of texture evolution at the center layer can be attributed to its strong initial cube texture.

Recrystallization of Ni-5%W Alloy Substrates by Reel-to-Reel Method

Abstract Cold rolled Ni-5at%W substrates with short length were annealed at different temperatures. On the basis of the results of annealing of short length substrates, the substrates with long length were annealed by reel-to-reel method. The hardness of the annealed substrates at different temperatures was analyzed. The recrystallization textures were evaluated by X-ray pole figure and the microstructure were investigated by optical microscopy. The effects of annealing temperature on the recrystalization texture were discussed. The differences of recrystallization texture between short length substrates and long length substrates were investigated. It is found that both short length substrates and long length substrates have very strong cube texture.

Effect of Initial Grain Size on the Evolution of {001}〈100〉 Texture in Severely Deformed and Annealed High-Purity Nickel

Development of cube texture ({100}〈001〉) was studied in high-purity Ni (99.97 pct) with widely different starting grain sizes (~28 and 650 μm) following ultrahigh straining (eeq = 6.4) by accumulative roll bonding (ARB) and annealing. The fine-grained starting material (FGSM) develops a much stronger cube texture after different annealing treatments as compared to the coarse-grained starting material (CGSM), despite their very similar bulk deformation texture. A lamellar type deformation structure is observed in both these materials, but the CGSM shows a more fragmented structure and frequent presence of shear bands. The recrystallization texture of the two materials differs right from the onset of recrystallization: cube-oriented grains nucleate and grow in the FGSM in sharp contrast to the nucleation and growth of randomly oriented grains in lamellar as well as shear-banded regions of the CGSM. The observed differences in the evolution of recrystallization texture in the two materials are discussed with regard to the microstructural differences and pertinent theories on the formation of cube texture.

Development of highly cube textured nickel superconductor substrate tapes by Accumulative Roll Bonding (ARB)

Abstract Development of cube texture ({001}〈100〉) has been investigated in pure Ni (99.97%) deformed to ultrahigh straining (e = 6.4) by accumulative roll bonding and then annealed at different temperatures for use as coated superconductor substrate. The as accumulative roll bonding processed sheets reveal a typical pure metal or copper type homogeneous deformation texture. After annealing at different temperatures, strong cube texture formation is observed and a nearly 100% cube textured tape with almost twin-free microstructure is obtained after annealing at 800°C for 1 h. The development of a sharp cube texture is accompanied by the development of a predominantly low angle boundary network. The very sharp cube texture formation in this material appears to be due to the oriented nucleation of cube grains at early stages of recrystallization and selective growth of these grains with progressing recrystallization. The results obtained indicate that accumulative roll bonding could be a very attractive route for fabricating highly cube textured superconductor substrate tapes from Ni.

Development of Textured Coated Superconductor Substrate Tapes by Severe Plastic Deformation Processing

An attempt has been made to fabricate highly cube textured ({001}<100>) polycrystalline nickel substrate tapes for coated superconductor applications using severe plastic deformation route. For this purpose high purity Ni (~99.97%) plates with widely different average grain size (28 µm or fine grained starting material and 650 µm or coarse grained starting material, respectively) are severely deformed by Accumulative Roll Bonding (ARB) up to an equivalent strain level of (εeq = 6.4) and annealed at various temperatures between 300° to 800°C for one hour. Upon annealing at different temperatures, the fine grained starting material developed a much stronger cube texture than the coarse grained starting material. By suitable annealing treatment near 100% cube textured tape could be obtained in the SPD processed fine grained nickel tapes having a predominantly low angle boundary network. The observed difference in the strength of cube texture in the two materials could be explained based on the oriented nucleation mechanism of formation of cube texture. The present results indicate that SPD processing route such as ARB is very effective in fabricating high purity Ni or Ni alloys intended for coated superconductor substrate applications.