Texture Components Research Articles

Effect of Dynamic Recrystallization Mode on Texture Components and Hardness for Nano-SiC Particles Reinforced Aluminum Matrix Composites Prepared Via Friction Stir Processing

Effect of Dynamic Recrystallization Mode on Texture Components and Hardness for Nano-SiC Particles Reinforced Aluminum Matrix Composites Prepared Via Friction Stir Processing

Anisotropic mechanism of cold-rolled pure titanium plate during the two-step tensile process of the variable path

The effects of pre-deformation on the macro-mesoscopic deformation characteristics of the titanium plate during variable path tensile were studied by a two-step tensile test and electron backscatter diffraction (EBSD). The Schmid law, Kernel Average Misorientation (KAM), Taylor axis, and In-Grain Misorientation Axis (IGMA) were used to forecast and identify the types and change laws of the activated deformation modes under different loading conditions. The results demonstrated that dislocation slip is the primary cause of the evolution of the basal split texture components. The nucleation and de-twinning of {10–12}ET resulted in the sudden appearance and disappearance of the <0001>//RD texture. The pre-tensile causes a texture redirection that reduces the activability of both prismatic <a> slip and pyramidal <a> slip in the following variable path tensile. Among them, prismatic <a> slip is the dominant deformation mechanism that causes yield and hardening behavior during RD tensile and TD-RD tensile (rolling direction-RD, transeverse direction-TD). A portion of the prismatic <a> slip is preferentially activated in TD tensile and RD-TD tensile deformation, and the deformation is subsequently jointly controlled by the prismatic <a> slip and the pyramidal <a> slip. The pre-tensile along RD promotes nucleation of {10–12} extension twin (ET) during subsequent RD-TD variable path tensile, while tensile along TD-RD coordinates plastic deformation by consuming a significant quantity of {10–12}ET generated during pre-tensile along TD. The formation of slip-assisted twins in neighboring grains is facilitated by the dislocation pile-up at grain boundaries, and the de-twinning phenomenon also cause the local dislocation pile-up to weaken.

Effects of Prior Solution Treatment on the Superior Strengthening of Texture Component of ECAPed Al–18Si–4.2Cu alloy

Effects of Prior Solution Treatment on the Superior Strengthening of Texture Component of ECAPed Al–18Si–4.2Cu alloy

Effect of Cold‐Rolling Deformation on Texture Evolution and Tensile Properties of Titanium Foil for Hydrogen Fuel Cell

Preparation of a titanium foil with weak anisotropy is of great significance for the development of bipolar plate materials for hydrogen fuel cell. However, the titanium foil obtained by rolling deformation often suffer from a severe deformation anisotropy due to the formation of a specific texture feature. In this study, the texture feature of pure titanium foil with different cold‐rolling reduction is characterized by electron back‐scattered diffraction (EBSD), and the effect of cold‐rolling deformation on texture evolution and tensile properties of titanium hfoil are systematically investigated. The results show that the cold‐rolling reduction could significantly affect the tensile anisotropy of titanium foil by regulating the texture characteristics. At the low level of cold‐rolling reductions (0%–30%), the texture of titanium foil is mainly pyramid texture, causing the obvious tensile anisotropy. At the medium level of cold‐rolling reductions (50%), strong basal‐plane texture components are appeared, causing that the activated slip system along transverse direction (TD) or normal direction (ND) is almost the same, and thus the tensile anisotropy gradually diminishes. At the high level of cold‐rolling reductions (70%), the intensity of basal‐plane texture becomes weak, and the tensile anisotropy appears in titanium foil again. The findings could provide theoretical guidance and technical support for the preparation of weak anisotropic titanium foil for hydrogen fuel cell.

Magnetic resonance image reconstruction based on image decomposition constrained by total variation and tight frame.

Magnetic resonance imaging (MRI) is a commonly used tool in clinical medicine, but it suffers from the disadvantage of slow imaging speed. To address this, we propose a novel MRI reconstruction algorithm based on image decomposition to realize accurate image reconstruction with undersampled k-space data. In our algorithm, the MR images to be recovered are split into cartoon and texture components utilizing image decomposition theory. Different sparse transform constraints are applied to each component based on their morphological structure characteristics. The total variation transform constraint is used for the smooth cartoon component, while the L0 norm constraint of tight frame redundant transform is used for the oscillatory texture component. Finally, an alternating iterative minimization approach is adopted to complete the reconstruction. Numerous numerical experiments are conducted on several MR images and the results consistently show that, compared with the existing classical compressed sensing algorithm, our algorithm significantly improves the peak signal-to-noise ratio of the reconstructed images and preserves more image details. Our algorithm harnesses the sparse characteristics of different image components to reconstruct MR images accurately with highly undersampled data. It can greatly accelerate MRI speed and be extended to other imaging reconstruction fields.

In situ neutron diffraction study and electron microscopy analysis of microstructure and texture evolution during annealing of rolled CoCrFeNi alloy doped with 1 at.%C

In situ neutron diffraction studies of changes in the dislocation density, volume fraction of carbides, and crystallographic texture have been performed during annealing of a cold-rolled multi-principal element CoCrFeNi alloy doped with 1 at.%C. In addition, microstructures of the as-rolled and several annealed samples of this alloy have been investigated using electron microscopy-based techniques. It is found that cold rolling to a thickness reduction of 74% results in a brass-type rolling texture with a spread of orientations between the Goss and brass components and with a pronounced 〈111〉//ND fiber. The deformed microstructure is characterized by a high density of dislocations and shows large variations in deformation structures in regions of different crystallographic orientations. In particular, bundles of deformation twins and high frequencies of shear bands are observed in regions having orientations along the 〈111〉//ND fiber. Annealing at 700 °C–1000 °C leads to recovery and recrystallization, during which shear bands and regions of mixed orientations act as preferential nucleation sites for recrystallized grains. Precipitation of M23C6 particles also takes place during annealing. The particles retard boundary migration, thus slowing down recrystallization and restricting grain growth. The average size of recrystallized grains does not exceed 5 μm even after annealing at 1000 °C for 60 min. While rolling textures are retained in some annealed samples, other samples demonstrate distinct recrystallization textures with new texture components. The results obtained in this work are compared with the literature data for several carbon-doped face-centered cubic multi-principal element alloys and for a carbon-free CoCrFeNi alloy.

Suppressing anisotropy in additive manufacturing by shear crystallographic texture development during multi-layer friction stir deposition

The solid-state additive manufacturing (AM) approach based on a strategy of sheet lamination (SL) using friction stir deposition/friction surfacing, and was investigated for multi-layer metal deposition in the present study. This resulted in synthesis of fully dense parts with a homogeneous and thermally stable fine-grain microstructure with isotropic properties by avoiding solidification-related defects and exploiting dynamic recrystallized shear crystallographic texture component. A non-heat-treatable AA5083 aluminum-magnesium alloy exhibiting serration yielding behavior was used for friction stir additive manufacturing (FSAM) solid-state deposition using a rotational speed of 1000 rpm with two working windows for the consumable rod feed rate in the range of 35–45 mm/min and a traverse speed in the field of 300–400 mm/min. The microstructural features and mechanical properties were assessed across different sections of the solid-state deposited AA5083 alloy structure to verify a pore-free structure with homogeneous and isotropic behavior. Metallography revealed the formation of uniform and refined equiaxed grains derived from continuous dynamic recrystallization (CDRX) with an average size of ∼4 μm over the entire region of the deposited wall through outstanding layers diffused adhesion. Mechanical testing of the multi-layer structure indicates isotropic tensile properties along the building direction (BD) and transverse direction, due to the shear crystallographic texture formed by thermo-mechanical processing during additive deposition process. An excellent combination of ultimate tensile strength (of 370 MPa) and elongation to fracture at ∼33 % was achieved enhanced by serration yielding tensile flow behavior due to solute element/dislocation interactions during plastic straining.

Crystallographic Texture Evolution in 3D Printed Polyethylene Reactor Blends.

In this work, crystallographic texture evolution in 3D printed trimodal polyethylene (PE) blends and high-density PE (HDPE) benchmark material were investigated to quantify the resulting material anisotropy, and the results were compared to materials made from conventional injection molded (IM) samples. Trimodal PE reactor blends consisting of HDPE, ultrahigh molecular weight PE (UHMWPE), and HDPE_wax have been used for 3D printing and injection molding. Changes in the preferred orientation and distribution of crystallites, i.e., texture evolution, were quantified utilizing the wide angle X-ray diffraction through pole figures and orientation distribution functions (ODFs) for 3D printed and IM samples. Since the change in weight-average molecular weight (Mw) of the blend was expected to significantly affect the resulting crystallinity and orientation, the overall Mw of the trimodal PE blend was varied while keeping the UHMWPE component weight fraction to 10% in the blend. The resulting texture was analyzed by varying the overall Mw of the trimodal blend and the process parameters in 3D printing and compared to the texture of conventional IM samples. The printing speed and orientation (defined with respect to the axis along the length of the samples) were used as the variable process parameters for 3D printing. The degree of anisotropy increases with an increase in the nonuniform distribution of intensities in pole figures and ODFs. All the highest intensity major texture components in IM and 3D printed samples (0° printing orientation) of reactor blends are observed to have crystals oriented in [001] or [001̅]. Overall, for the same throughput, 3D printed samples in the 0° orientation showed greater texture evolution and higher anisotropy compared to IM samples. Most notably, an increase in 3D printing speed increased the crystalline distribution closer to the 0° direction, increasing the anisotropy, while deviation from this printing orientation reduced crystalline distribution closer to the 0° direction, thus increasing isotropy. This demonstrates that tailoring material properties in specific directions can be achieved more effectively with 3D printing than with the injection molding process. Change in the overall Mw of the trimodal PE blend changed the preferential orientation distribution of the crystal planes to some degree. However, the degree of anisotropy remained the same in almost all cases, indicating that the effect of molecular weight distribution is not as significant as the printing speed and printing orientation in tailoring the resulting properties. The 3D printing process parameters (speed and orientation) were shown to have more influence on the texture than the material parameters associated with the blend.

Microstructure and Texture Evolution in Cold-Rolled and Annealed Oxygen-Free Copper Sheets.

Commercial oxygen-free copper sheets were cold-rolled with reduction rates ranging from 20% to 87% and annealed at 400, 500 and 600 °C. The microstructure and texture evolution during the cold-rolling and annealing processes were studied using optical microscopy (OM), scanning electron microscopy (SEM) and electron back-scattered diffraction (EBSD). The results show that the deformation textures of {123}<634> (S), {112}<111> (Copper) and {110}<112> (Brass) were continuously enhanced with the increase in cold-rolling reduction. The orientations along the α-oriented fiber converged towards Brass, and the orientation density of β fiber obviously increased when the rolling reduction exceeded 60%. The recrystallization texture was significantly affected by the cold-rolling reduction. After 60% cold-rolling reduction, Copper and S texture components gradually decreased, and the {011}<511> recrystallization texture component formed with the increase in annealing temperature. After 87% cold-rolling reduction, a strong Cube texture formed, and other textures were inhibited with the increase in annealing temperature. The strong Brass and S deformation texture was conducive to the formation of a strong Cube annealing texture. The density of the annealing twin boundary decreased with the increase in annealing temperature, and more annealing twin boundaries formed in the oxygen-free copper sheets with the increase in cold-rolling reduction.

Revealing the inhomogeneous nature of microstructure and texture evolution in the cold-rolled CoCrFeMnNi alloy during static recrystallization

In the present investigation, equiatomic CoCrFeMnNi high entropy alloy (HEA) was subjected to 80% cold rolling (as-rolled) followed by isothermal annealing treatment at 700 °C for different time periods. Microstructural characterization was performed using electron back-scattered diffraction (EBSD) and electron channeling contrast imaging (ECCI) techniques on the as-rolled and annealed samples. The as-rolled microstructure consisted of elongated grains mainly composed of strong α-fiber and weak γ-fiber textures. The as-rolled sample showed the formation of ingrain SBs in the γ-fiber grains, which served as preferential sites for grain nucleation. The annealing treatment of as-rolled samples at 700 °C cause static recovery (SRV) before 5 minutes of heat-treatment, whereas static recrystallization (SRX) was observed after 5 minutes of heat-treatment in the CoCrFeMnNi alloy samples. A faster rate of recrystallization kinetics was observed after 15 minutes of heat-treatment. The annealing treatment reduced the intensity of α-fiber and enhanced the Copper, Cube and P ({011}<122>) texture components. Copper components originated from coarse recrystallized grains, which were the results of localized grain growth phenomena. Unusual behavior of banded featured α-fiber grains was observed during the annealing process. These banded grains in the partially annealed samples consisted of subgrain-boundaries and showed a delayed response to recrystallization as compared to grains with other orientations. Stored energy (SE) and Taylor factor (M) calculations were also used to understand the delayed recrystallization response of the banded featured/retained deformed grains. The microhardness value of the as-rolled sample was approximately 450 Hv, which decreased to around 230 Hv for the fully recrystallized grains.

Microstructure, tensile strength, and hardness of AA5024 modified with ZrH4 additions produced by laser powder bed fusion

This work investigates the effect of ZrH4 additions on a commercial AA5024 aluminum alloy produced via Laser Powder Bed Fusion (L-PBF) where pre-mixed powders of AA5024 and ZrH4 were used. The microstructure was characterized using light and scanning electron microscopy assisted by energy-dispersive X-ray spectroscopy, and electron backscattered diffraction. The mechanical properties were evaluated by hardness and tensile measurements. The ZrH4 additions modify the microstructure. Regions without particles originate the large and elongated grains, while regions with undissolved ZrH4 or formed particles during solidification originate a fine equiaxed microstructure. The fine-grained region is typically located at the boundary of the melt pools, while the coarse-grained region is formed within the melt pools. There is substantial grain refinement with additions higher than 2.0 wt% ZrH4, nearly eliminating the coarse-grained region. The grain size does not differ in the fine-grained region for the different ZrH4, cross-sections (perpendicular or along the printing direction), or printing parameters. The 〈110〉 crystallographic fiber texture is identified, and a few particular texture components are more pronounced, such as the Cube {001} 〈100〉, the rotated Cube {001} 〈110〉, the Goss {011} 〈001〉, and Z {111} < 110>. Low texture index values are obtained in the fine-grained region, indicating the highly isotropic microstructure. The hardness and tensile strength increase with the increase in ZrH4 content for the as-built condition. A saturation in tensile strength is reached after 1.0 wt% ZrH4 additions.

In-situ monitoring of additive friction stir deposition of AA6061: Effect of rotation speed on the microstructure and mechanical properties

The AA6061 alloy depositions fabricated under three rotation speeds (Ω, 450, 500 and 550 rpm) are obtained by the additive friction stir deposition (AFSD) technique in this study. The real-time temperature, force and torque during the AFSD process were monitored by a self-developed process-aware kit, helping to thoroughly investigate the influence of Ω on the microstructure and mechanical properties of the depositions. Combined with the results of the electron back scattered diffraction (EBSD) analysis on a large area (4 × 4 mm2), it is found that the grain size increases with the increase of Ω due to high heat generation. The proportion of deformation texture components reduces because of the lower strain distribution as well as the slight deformation behavior. A higher average micro-hardness is found on the 550 rpm-deposition because of the dislocation strengthening effect. Furthermore, the values of yield strength (87.8 MPa) and ultimate tensile strength (147.2 MPa) of the depositions are the highest when the Ω is the lowest (450 rpm), owing to the lowest thermal cycle. All the results are intended to provide useful guidance and a theoretical basis for producing high-performance Al-based alloys through AFSD.

Effect of torsional deformation on microstructure and mechanical properties of pure copper

This study investigates the influence of torsional deformation with different equivalent strains on the microstructural evolution and mechanical properties in pure copper at room temperature. The grain size exhibits a gradient distribution pattern with decreasing shear strains. Texture analysis reveals the development of a typical torsion texture during deformation. And the texture component is significantly influenced by the strain level. In samples subjected to low strain at the center position, the dominant texture components are mainly A and A* components. As strain increases in the 1/4 layer sample region, there is a gradual decrease in strength for A* component, while A component remains dominant; additionally, B and C textures exhibit increased strength. At positions subjected to maximum strain near the surface area, B texture replaces A as the strongest texture component. Results also indicate that torsional deformation enhances hardness, strength, and plasticity due to dislocation strengthening, fine grain strengthening and synergistic effects during deformation. Furthermore, the formation of torsional texture during this process may contribute to improved plasticity.

Unexpected texture transition induced by grain growth during static annealing of a dilute Mg-1Al alloy

Conventional rolled Mg-Al alloy sheets typically exhibit strong basal textures that remain and may even strengthen after recrystallization annealing due to the preferential growth of basal-oriented grains, resulting in poor formability at room temperature. Therefore, the knowledge of recrystallization and grain growth is critical for modifying textures of Mg-Al alloy sheets. The static recrystallization and texture evolution in a cold-rolled dilute Mg-1Al (wt.%) alloy during various annealed temperatures ranging from 300 °C to 450 °C, have been investigated using the quasi in-situ electron backscatter diffraction (EBSD) method. The as-rolled Mg-1Al alloy shows a dominant basal texture, which weakens and broadens in the rolling direction (RD) during the subsequent annealing, accompanied by the formation of 〈101¯0〉 texture component. Particularly, the 〈101¯0〉 texture component is more pronounced after annealing at high temperatures. The quasi in-situ EBSD results show that recrystallized grains are mainly induced by shear bands, which exhibit a wide spectrum of orientations with c-axis tilt angles ranging 20°-45° from the normal direction (ND). Orientations of shear band-induced recrystallized grains are retained during the entire recrystallization process, resulting in a reduction in the texture intensity. Moreover, recrystallized grains belonging to the 〈101¯0〉 texture component grow preferentially compared to those with other orientations, which is attributed to low energy grain boundaries, especially grain boundaries with ∼30° misorientation angles. Furthermore, the high temperature annealing facilitates the rapid growth of grain boundaries having a 30° misorientation angle, leading to the occurrence of distinct 〈101¯0〉 texture after annealing at 450 °C for 1 h. The results provide insights for texture modification of rare earth-free low-alloyed Mg alloys by controlling annealing parameters.

Theoretical prediction of texture requirements for improving the intrinsic cleavage crack resistance of BCC Fe

Based on the classical Rice model of crack tip dislocation emission, the present article provides a theoretical prediction of suitable grain orientations (texture components) in a rolled polycrystalline BCC Fe plate which can improve the overall resistance to cleavage crack propagation. Besides, the beneficial effect of alloying additions on further improvement in the intrinsic crack resistance of the steel is also discussed pertaining to the role of unstable stacking fault energy.

Texture Analysis of Hot Rolled Martensitic and Bainitic Steels by Electron Backscatter Diffraction to Quantify Parent Austenite States

To measure textures of hot rolled martensitic and bainitic steels, electron backscatter diffraction (EBSD) is applied to large areas, each covering about a thousand of prior grains. A scanning step is selected to keep reasonable time of the data acquisition still providing in any grain a significant number of analyzed points. Contributions to the transformation texture appearing from deformation and recrystallization components of the parent texture are estimated with the Bain relationship. To assess the parent austenite state, their proportion is then expressed by a scalar parameter. The results are verified by independent metallographic data. Avoiding the reconstruction of prior grains, this statistical approach will facilitate evaluation of complex austenite structures with comparable fractions of dissimilar material states.

Study on the texture evolution and mechanical properties of selective laser melting pure nickel

As a ductile and ferromagnetic transition metal, nickel possesses exgrainent metallurgical compatibility, corrosion resistance, high electrical conductivity and high temperature stability. This study investigates the influence of energy density on the microstructure and properties of laser powder bed fusion pure nickel. The research results demonstrate that: during the formation process of Ni, with the increase in energy density, the grain texture exhibits anisotropy. The surfaces parallel and perpendicular to the building direction demonstrate strong {111} and {220} textures respectively. Primary and secondary recrystallization leads to increase in texture strength, subsequently affecting the decrease in dislocation density. The {111} texture yields preferentially, while the {220} single-crystal-like microstructure (SCM) requires higher energy density to complete primary recrystallization and trigger the recovery and enhancement of {111} texture. The enhancement in tensile properties is mainly attributed to the improvement of unmelted defects and texture. With the loading of stress, the failure of the structure leads to a decrease in the strength of the optimal texture component. The {220} texture strengthens the bond between different cladding layers along the building direction, resulting in numerous epitaxial grains parallel to the building direction on the fracture surface, significantly increasing the elongation of the specimen.

The effect of crystallographic orientation on globularization and texture evolution during the annealing of a near α titanium alloy tube

In order to weaken the rolling texture of the cold-rolled tube and improve its secondary forming ability, this paper studies the influence mechanism of different annealing times on the microstructure and texture evolution of Ti-6Al-3 Nb-2Zr-1Mo tube after intermediate-temperature annealing. The results show that as the annealing time increases from 30 minutes to 120 minutes, the degree of globularization of α/β phases significantly increases. The globularized structure mainly consists of equiaxed α particles, which are surrounded by necklace-like globularized β phases. The original rolling texture component did not change after 30-minute annealing. The intensity of the rolling texture was weakened, and two new components appear after 120 minutes of annealing. The appearance of these two components was caused by the growing up of globularized α phases close to the Burgers orientation relationship (BOR) with surrounding β phases during a long annealing process. Moreover, it was observed that globularization to some extent broke the BOR between α phase and the adjacent β phase.

Evolution of microstructure and texture and their influence on the strength of an accumulative roll bonded (ARBed) Al-Sc-Zr-Er-Ti alloy

Accumulative roll bonding (ARB) is an effective approach to improve the strength of metal sheets. This work studied the evolution of microstructure and texture and their influence on the strength of an ARBed Al-Sc-Zr-Er-Ti alloy, produced by multi-microalloying Sc, Zr, Er, and Ti into pure Al. A high-quality interface and a fine microstructure with an average grain size of ∼0.6 μm were achieved as by the ARB process. The Dillamore {4411} <11118> and the Copper {112} <111> components were sharpened in final texture as is common in ARB. However, after the 5th cycle, there was a new texture component along the α-fiber, at (φ1, Φ, φ2) ≡ (60°, 45°, 0°) in Euler space. The yield strength (YS) and tensile strength (UTS) increased with increasing the number of ARB cycles. The 7th ARBed Al-Sc-Zr-Er-Ti alloy had increased YS by 45% and UTS by 57%, respectively, compared to the initial cold rolled sheet. Strengthening was mainly attributed to dislocation strengthening, grain refinement strengthening and precipitation strengthening. There was little texture strengthening because of a strengthening and softening alternation with the change of ARB cycle.

Hot deformation behavior of commercial pure vanadium

The hot deformation behavior of pure vanadium was studied by uniaxial compression tests carried out in vacuum to a true strain of 0.6 in the temperature range of 800 to 1400 °C and strain rate range of 3 × 10−3 to 10 s−1. Strain rate sensitivity was calculated from the compression test data and mapped out in contour plots to determine the optimum regime of hot workability of vanadium. A high strain rate sensitivity of about 0.3 was obtained in the temperature and strain rate range of 1100 to 1400 °C and 3 × 10−3 to 1 s−1 for pure vanadium. Microstructures of the deformed samples showed features of dynamic recrystallization within the high strain rate sensitivity domain. Dynamic abnormal grain growth was observed at 1400 °C and strain rates of 0.1 and 1 s−1. The apparent activation energy of deformation was found to be 244 kJ·mol−1 and the stress exponent was about 3.4. The high values of activation volume suggest the barriers related to the dislocation intersection based process as the main rate controlling mechanism during the hot deformation of vanadium. The 〈100〉 and 〈111〉 fiber texture components evolved during the hot deformation of pure vanadium.