Copper-type Rolling Texture Research Articles

Intermediate annealing and strong cube texture of Ni-5at.%W alloy thin substrates for YBCO coated conductors

In this work, a series of studies have been carried out on ultra-thin Ni-5at%W (Ni5W) alloy substrates used for the coated conductors. The ultra-thin Ni5W alloy substrate can be fabricated for the large square REBCO film with a size of over 40 mm × 40 mm, which is normally used in scenarios to support a magnetic field in a specific area. To obtain a stronger recrystallized cubic texture, the intermediate annealing was added to optimize the rolling texture during the rolling process of the Ni5W alloy substrate. A typical copper-type rolling texture was obtained in the substrate which intermediate annealed at 96.25%, and the cube texture reached 97.6% after annealing recrystallization. Moreover, The deformation and recrystallization of 40 μm thick Ni-5at%W (Ni5W) alloy thin substrates were investigated by the quasi-in situ method. The fabrication of ultra-thin Ni5W substrates increases the potential of miniaturizing lightweight coated conductors, which helps to further promote and accelerate the manufacturing process of the entire coated conductor strip.

Formation of Recrystallization Cube Texture in Highly Rolled Ni–9.3 at % W

In this work the formation of strong recrystallization cube texture in heavily rolled Ni–9.3 at % W has been studied. During the cold rolling (also known as recovery-rolling) process the deformation texture of Ni–9.3 at % W alloy (further notated as Ni9W) transforms to Copper-type rolling texture, and after annealing, a sharp cube texture is generated. It is remarkably strong recrystallization cube texture, as high as 93 vol %, in metallic materials with low stacking fault energy. The formation mechanism of the cube texture is adopted for the rapid recovery of cube nuclei at the early stage of recrystallization as well as fast migration rate of high angle boundaries between cube grains and deformed microstructure at high temperature. Considering the cold rolling texture of Ni9W, oriented nucleation seems to play more important role in the cube texture formation process. In this article, the relationship between the deformation texture and recrystallization cube texture is discussed.

Cube texture evolution of Ni5W alloy substrates and La–Zr–O buffer layer of YBCO-coated conductors

The cube texture evolution of Ni-5 at%W alloy deformed up to a very high strain was thoroughly investigated by X-ray diffraction (XRD) and electron back-scattered diffraction (EBSD) during the process of deformation, recrystallization and grain growth. A typical copper-type rolling texture, mainly consisting of components of S, copper and brass orientations, is obtained after heavy cold rolling. The fraction of rolling texture is slightly strengthened during recovery and then strongly reduced during recrystallization process. The cube texture is formed by consuming the rolling texture components during the discontinuous recrystallization process. The cube grains have a size advantage with respect to the non-cube grains. A strong cube-textured Ni5W alloy substrate with cube texture area fraction of 98.2 % (<10°) is obtained after annealing at 1050 °C for 1 h. The full width half maximum (FWHM) values for the X-ray (111) φ-scan and the (002) ω-scan of this substrate are 5.84° and 4.76°, respectively. Furthermore, the area fraction of {001} 〈110〉 orientation of the epitaxially grown La2Zr2O7 buffer layer is 97.1 % (<10°), and the FWHM values of (111) φ-scan and (002) ω-scan are 5.22° and 5.00°, respectively.

Weakening rolling texture in a nanotwinned copper

A randomly oriented copper embedded with nanotwin bundles was prepared by means of dynamic plastic deformation at cryogenic temperature. The subsequent cold rolling at room temperature induced shearing of nanotwin bundles, and resulted in a lamella structure after 90% thickness reduction. The volume fraction of copper-type rolling texture of the rolled nanotwinned copper is about 24.9±4.9vol%, much less than the rolled coarse-grained (~76vol%) and ultrafine grained ones. Detailed microstructure and texture characterizations show that the weaker texture is attributed to the evolution of nanotwin bundles retarding the formation of texture during cold rolling.

Texture evolution in the Fe-30.5Mn-8.0Al-1.2C and Fe-30.5Mn-2.1Al-1.2C steels upon cold rolling

Crystallographic textures of the austenitic low-density Fe-30.5Mn-8.0Al-1.2C (8Al) and Fe-30.5Mn-2.1Al-1.2C (2Al) (wt.%) steels were examined during cold rolling by means of electron backscatter diffraction (EBSD) and electron channeling contrast imaging (ECCI). Random oriented grains orient towards Goss- and brass-components along the α-fiber as the strain increased, with activation of slip, mechanical twinning, and shear banding, for both steels. S- and copper-orientations were also observed in the 8Al steel at 50% reduction. The route of Cu-CuT-Goss-brass texture evolution was found in the 2Al alloy. Cu, Goss, and brass textures occur as a dominant texture in the deformed 8Al alloy. Copper-type texture accompanied with slip at low reduction (20%), as well as Cu-type shear bands, and shear banding inside Goss-oriented grains at higher reduction (50%), were observed in the 8Al steel. It is suggested that this copper-type rolling texture may be attributed to the Al addition, which contributes to its low twinning activity compared to that in the 2Al alloy. Cu-CuT-brass f.c.c. rolling texture transition to form the Brass-type texture was observed at higher reduction in the 2Al alloy with strong similarity to that found in other Fe-Mn-C system TWIP steels.

Evolution of Cube Texture in Cu-45at.%Ni Alloy Substrates for YBCO Coated Conductors

The cube texture evolution during annealing of the heavy cold-rolled Cu-45at.%Ni alloy tapes were investigated by XRD and electron back scattering diffraction techniques. The results indicated that the fraction of Copper-type rolling texture was slightly strengthened during recovery, and then strongly reduced during recrystallization. The cube texture was formed by consuming the rolling texture components during recrystallization process, and the S, Copper and Brass orientations were consumed together via cube grain growth. A strong cube-textured Cu-45at.%Ni alloy substrate with the cube texture fraction of 98.6 % (&lt; 10°) was obtained after annealing at 1000 oC for 1 h.

Role of stacking fault energy on texture evolution revisited

Three materials, pure aluminium, Al-4 wt.% Mg, α-brass have been chosen to understand the evolution of texture and microstructure during rolling. Pure Al develops a strong copper-type rolling texture and the deformation is entirely slip dominated. In Al-4Mg alloy, texture is copper-type throughout the deformation. The advent of Cu-type shear bands in the later stages of deformation has a negligible effect on the final texture. α-brass shows a characteristic brass-type texture from the early stages of rolling. Extensive twinning in the intermediate stages of deformation (εt ∼ 0.5) causes significant texture reorientation towards α-fiber. Beyond 40% reduction, deformation is dominated by Bs-type shear bands, and the banding coincides with the evolution of <111>IIND components. The crystallites within the bands preferentially show <110>IIND components. The absence of the Cu component throughout the deformation process indicates that, for the evolution of brass-type texture, the presence of Cu component is not a necessary condition. The final rolling texture is a synergistic effect of deformation twinning and shear banding.

Grain size dependent texture evolution in severely rolled pure copper

Large strain rolling – up to 97% thickness reduction – was carried out on pure copper with two different initial grain sizes: coarse-grained (CG, 24μm) and ultrafine-grained (UFG, 360nm). After rolling, classical copper-type rolling texture was obtained for the CG copper while a brass-type rolling texture was observed in the starting UFG copper, obtained by eight-pass equal channel angular pressing at room temperature prior to rolling. Using the Viscoplastic Self Consistent polycrystal model, it is found that the deformation mechanism at large rolling strain is grain size dependent and a change in the major slip mode has a large impact on the type of deformation texture. The brass-type texture in the UFG material can be simulated using {111} <112¯> partial slip together with {111} <11¯0> slip and a small amount of twinning; for the CG material, only {111} <11¯0> slip is needed to reproduce the copper-type rolling texture. Further, it is found that the polycrystal deformation condition approaches Taylor behavior in the UFG material whereas much more strain heterogeneity is present in rolling of the CG copper. By orientation imaging electron microscopy the geometrically necessary dislocation (GND) density is found to be decreasing in the UFG rolled samples while increasing in the CG case. This tendency corroborates the texture simulation parameters concerning strain heterogeneity.

Microstructure and Phase Transformations Near the Bonding Zone of Al/Cu Clad Manufactured by Explosive Welding / Zmiany Mikrostrukturalne I Fazowe W Pobliżu Strefy Połączenia Układu Warstwowego Al/Cu Wytworzonego Technologią Zgrzewania Wybuchowego

The structure near the interface of bimetallic strips strongly influences their properties. In this work, the interfacial layers of explosively welded aluminium and copper plates were investigated by means of a scanning electron microscope (SEM), equipped with a high resolution system for local orientation measurements (SEMFEG/EBSD), and a transmission electron microscope (TEM), equipped with energy dispersive spectrometry (EDX) for the analysis of chemical composition changes. The SEMFEG/EBSD-based local orientation measurements in the areas close to the interface, in both sheets, revealed fine-grained layers characterized by the clearly marked tendency of the copper-type rolling texture formation. The texture was described by an increased density of the orientations near the {112}&lt;111&gt;, {123}&lt;634&gt;and {110}&lt;112&gt;positions. The internal microstructure of the intermetallic inclusion is mostly composed of dendrites. The electron diffractions and the TEM/EDX chemical composition measurements in the intermetallic inclusions revealed only crystalline phases, both equilibrium and ’metastable’. Additionally, no significant regularity in the phase distribution with respect to the parent sheets was observed.

Experimental Investigation of Texture Gradients in Aluminium/Copper Plates Bonded through Explosive Welding Process

In this study, the commercial purity Al/Cu plates were bonded through the explosive welding process. The SEM/EBSD local orientation measurements were conducted to consider the changes in the microstructure and the development of texture gradients for the applied explosive loading. A particular attention was paid to the texture changes across the interface. The detailed local orientation measurements show that the ultra-fine grained layers are formed close to the bonding zone. The layers were characterized by the copper-type rolling texture components. The interface was outlined by a characteristic sharp transition between the two materials. However, in some places, local melted zones were also encountered, mainly in the front slope of the waves.

Deformation banding in copper

Abstract A crystallographic etching technique has been used to demonstrate that deformation banding is an important deformation mode in copper. In a cold-rolled coarse-grained copper, deformation banding occurs and the different banding geometries divide the grains into a large number of regions with different orientations. Because of the important effect on microstructure, deformation banding is considered to influence the development of deformation texture. In particular, the {110}〈112〉 texture component, an important component of the copper-type rolling texture which cannot be explained by existing deformation models, is shown to be formed by deformation banding.

On Penetration of Shear Texture into the Rolled Aluminum and Copper

The most important cause of the macroscopic inhomogeneity of texture is the nonuniformity of the penetration of the shear deformation through the thickness of the rolled metal. The authors have proposed a method making possible the observation of the penetration of shear texture from layer to layer. The method involves measuring the angles that describe the rotation of the {001}«110» shear orientation toward the copper-type rolling texture. Rolling with large draughts causes the penetration of the shear texture from the surface toward the sheet center, inducing a change in the characteristics of the inhomogeneity of texture. This mechanism is related both to the geometry of the rolling gap and to the mechanical properties of the deformed metal.