Texture Volume Fractions Research Articles

Effect of equal channel angular pressing on microstructure and mechanical properties of a Cu-Cr-Ni-Si-Co alloy

The microstructural and properties of a Cu-Cr-Ni-Co-Si alloy produced by equal channel angular pressing (ECAP) were systematically investigated. After the fourth-pass ECAP deformation, the average grain size was refined from 30 μm (solid solution state) to below 3 μm, resulting in a fine and regularly shaped equiaxed crystalline microstructure. The distribution of grain boundaries became more uniform. During ECAP deformation, the volume fraction of Copper texture {001} <100> decreased, while that of the Brass {011} <211> increased, and the Shear {123} <634> remained nearly constant. An increase in the number of ECAP deformation passes facilitated dynamic recrystallization, leading to an increase in the fraction of the recrystallized texture. After thermomechanical treatment (first-pass ECAP +450 °C aged/120 min + 80 % cold-deformation +450 °C aged/30 min), the alloy exhibited good mechanical properties, with a tensile strength of 546 MPa, a yield strength of 475 MPa, an elongation of 18.2 %, and an electrical conductivity of 52.8 %IACS. The main strengthening mechanisms included precipitation strengthening, dislocation strengthening and grain boundary strengthening, with the precipitation strengthening accounting for 45.6 % of the yield strength.

Understanding the isothermal compression behavior of Al-Mg-Si alloy based on hot deformation parameters and instability criteria

This work comprehensively studied the microstructure evolution and thermodynamic behavior of homogenized cast Al-Mg-Si alloy by using the dynamic materials model (DMM) of hot deformation activation energy (Q) and power dissipation efficiency (η), which were influenced by Zener-Holomon (Z) parameters of temperature-compensated strain rate. The Q varies with the material constitutive parameters n(T) and sε̇ and leads to a non-monotonic trend in the Z parameter. These coupling relationships have profound significance for revealing plastic deformation. The microstructure and microtexture evolution under four representatively Z parameters had been characterized, and it was found that the deformation mechanism under higher lnZ was mainly dynamic recovery (DRV) and a typical <101>//TD texture with a maximum strength of 14.41 was exhibited. As lnZ decreased, the volume fraction of high angle grain boundaries (HAGBs) and recrystallized grains increased from 20.89 % and 1.5 % to 49.47 % and 40.9 %, the geometrically necessary dislocation (GNDs) density dropped from 1.55 × 1014/m2 to 0.40 × 1014/m2, and the softening mechanism gradually shifted to dynamic recrystallization (DRX), with the volume fraction of Cube texture {001} <100> increasing and Goss texture {011} <110> decreasing. Hot processing maps were established based on the Prasad and Murty instability criterion. The results showed that the instable and stable zones had a strong correlation with η. Lower η often implies microcracks, deformation bands and flow localization, as well as extremely uneven grain distribution and a low recrystallization volume fraction, and the stable zone mainly exhibited the phenomenon of DRX dominated recrystallization behavior improving microstructure homogenization. By comparing the specific hot processing map and microstructure evolution, the prediction ability for determining Murty instability criterion is stronger than Prasad for homogenized cast Al-Mg-Si alloy.

Crystal Plasticity Finite Element Simulation of Grain Evolution Behavior in Aluminum Alloy Rolling.

In this study, the crystal plasticity finite element method was established by coupling the crystal plasticity and finite element method (FEM). The effect of rolling deformation and slip system of polycrystalline Al-Mg-Si aluminum alloy was investigated. The results showed that there was a pronounced heterogeneity in the stress and strain distribution of the material during cold rolling. The maximum strain and shear strain occurred at surface of the material. The smaller the grain size, the lower the strain concentration at the grain boundary. Meanwhile, a smaller strain difference existed between the grain interior and near the boundary. The rotation of grains leads to significant differences in deformation and rotation depending on their initial orientations during the rolling process. The slip system of (11-1)<-110> had a large effect on the plastic deformation, (111)<10-1> is second, and the effect of (1-11)<011> slip system on the plastic deformation is the smallest. After deformation, the grain orientation concentration was increased with deformation. Therefore, both the strength and volume fraction of texture were increased with the increase in rolling deformation. The experimental results of EBSD indicated that the large rolling reduction resulted in severe grain twisting, so the texture strength was increased. The simulation results were in close agreement with the experimental results. This study provides a theoretical basis for the rolling process, microstructure, and performance control of aluminum alloys.

Crystallographic characteristics and mechanical behavior of laser welded joints of hot roll bending parts

In this work, laser welding was performed on the hot roll bending parts obtained by local-induction-heating bending forming. The influence of the crystallographic characteristics of the phase transformation products in different regions of the laser welded joint on the mechanical properties was systematically studied, and the reasons for the performance degradation were discussed in detail. The results show that upper-critical HAZ (UCHAZ) forms coarse prior austenite grain (PAG) and bainite, resulting in the lowest dislocation density of 2.5 × 1014 m−2 and the lowest impact toughness value of 46 J/cm2. Sub-critical HAZ (SCHAZ) forms tempered martensite, causing the joint to soften and the tensile strength to decrease by 18%. The number of variants in SCHAZ is the lowest, where short laths with smaller misorientations merge into long laths, and precipitates nucleation and growth occurs. The uniform orientation of the variants in SCHAZ forms low-angle grain boundaries (LAGBs), which reduces the hindrance to crack propagation, so the mechanical properties of SCHAZ decrease. In addition, the texture analysis found that UCHAZ has the highest 〈001〉//RD orientation volume fraction, indicating that UCHAZ is most prone to rapid expansion of brittle cracks on the {001} cleavage plane, so the toughness of UCHAZ is reduced. SCHAZ has the highest {001}〈110〉 texture volume fraction and the lowest proportion of high-angle grain boundaries (HAGB), indicating that the deformed grain structure with the {001} cleavage planes distributed along the LAGB after welding heat tempering is the main reasons for the delamination of SCHAZ.

Effect of hot rolling finishing temperature and intermediate annealing on the microstructure, texture evolution, and comprehensive properties of Al-Mg-Si alloy

The effect of varying hot rolling finishing temperature and the application of intermediate annealing on the microstructure, texture evolution, and mechanical properties—including forming, hemming, and roping properties—of Al-Mg-Si alloy sheets was systematically investigated. The hot-rolled plate with a higher rolling finishing temperature exhibits a significantly higher volume fraction of Cube texture which is readily retained and inherited to the final state microstructure. A substantial quantity of Mg2Si particles can also be observed in this plate, while the amount notably decreases at lower rolling finishing temperatures. These large quantities of Mg2Si hinder the PSN effect, subsequently encouraging Cube texture and hindering CubeND texture formation during solute solution. Following intermediate annealing, Ostwald ripening mechanism leads to finer Mg2Si particles dissolve while the coarser Mg2Si continue to grow, reducing the obstruction to the PSN effect. The T4P sheets without intermediate annealing exhibit a significant volume fraction of Goss texture. Goss texture can be effectively minimized by applying intermediate annealing process and thus almost disappears in T4P sheets that undergo intermediate annealing. Cube texture proved advantageous for hemming processes but detrimental to both formability and roping performance; thus, it should be modulated within an optimal range. On the other hand, Goss texture negatively impacted all mechanical properties and should be minimized or eliminated. Optimal comprehensive properties can be achieved by lowering the hot rolling finishing temperature and implementing a suitable intermediate annealing treatment.

Three-dimensional mapping of mineral in intact shark centra with energy dispersive x-ray diffraction

The centra of shark vertebrae consist of cartilage mineralized by a bioapatite similar to bone's carbonated hydroxyapatite, and, without a repair mechanism analogous to remodeling in bone, these structures still survive millions of cycles of high-strain loading. The main structures of the centrum are an hourglass-shaped double cone and the intermedialia which supports the cones. Little is known about the nanostructure of shark centra, specifically the relationship between bioapatite and cartilage fibers, and this study uses energy dispersive diffraction (EDD) with polychromatic synchrotron x-radiation to study the spatial organization of the mineral phase and its crystallographic texture. The unique energy-sensitive detector array at beamline 6-BM-B, the Advanced Photon Source, enables EDD to quantify the texture within each sampling volume with one exposure while constructing 3D maps via specimen translation across the sampling volume. This study maps a centrum from two shark orders, a carcharhiniform and a lamniform, with different intermedialia structures. In the blue shark (Prionace glauca, Carcharhiniformes), the bioapatite's c-axes are oriented laterally within the centrum's cone walls but axially within the wide wedges of the intermedialia; the former is interpreted to resist lateral deformation, the latter to support axial loads. In the shortfin mako (Isurus oxyrinchus, Lamniformes), there is some tendency for c-axis variation with position, but the situation is unclear because one dimension of the sampling volume is considerably larger than the thickness and spacing of the intermedialia's radially-oriented lamellae. Because elastic modulus in collagen plus bioapatite mineralized tissues varies significantly with both volume fraction of bioapatite and crystallographic texture, the present 3D EDD-derived maps should inform future 3D numerical models of shark centra under applied load.

Influence of asymmetric rolling on the microstructure, texture evolution and mechanical properties of Al–Mg–Si alloy

The influence of asymmetric rolling on the microstructure, texture and mechanical properties of Al–Mg–Si alloy was investigated comprehensively through finite element simulation (FEM), microstructure and texture characterization, and tensile testing. Cold rolling was applied by imposing different velocity ratios (from 1 to 1.75) between the upper and lower rolls. The results show that asymmetric rolling has some effects on the shear strain, microstructure, texture and mechanical properties. The shear strain always exhibits a non-uniform distribution throughout the sheet thickness, and it is closely related to the velocity ratio; improving the velocity ratio could result in a larger shear strain in the surface contacting the roll with a higher velocity. As the velocity ratio increases, the cold rolled alloy sheet contains an increasing number of fine equiaxed grains, and the solution-treated recrystallization grain structure gradually becomes fine. Unlike symmetric rolling, asymmetric rolling can result in the development of TD-rotated β fiber, and the rotation angle is largely dependent on the velocity ratio. Although no ideal shear texture E {111}<110> and F{111}<112> orientations were developed, the shear texture H{001}<110> orientation appears by applying a sufficient velocity ratio. After solution treatment, the velocity ratio has no influence on the texture component, but improving the velocity ratio can reduce the texture volume fraction. Asymmetric rolling plays a positive role in improving mechanical property. As the velocity ratio increases, there are increases in the strength, elongation and plastic strain ratio R, and a decrease in the planar anisotropy ΔR, which is likely attributable to the weak texture.

Comprehensive Influence of the Normalized and Final Annealing Process on High‐Strength Nonoriented Silicon Steel

High‐strength nonoriented silicon steel is widely used to make automobile engines. On the basis of ensuring certain magnetic properties, it also needs higher mechanical properties. The matching of magnetic and mechanical properties can be achieved by comprehensive control of normalized and final annealing. Different annealing temperatures and times are applied to clarify the change of texture, thus influencing magnetic induction, iron loss, and mechanical properties. Route B obtains the optimal normalization effect. The type and volume fraction of texture in the final annealing sheet differ a lot after incomplete and fully normalized annealing, depending on the degree of recrystallization. The final texture composition remains unchanged when normalized annealing is incomplete, while full normalized annealing leads to the disappearance of some textures. The mechanical and magnetic properties of the final annealing sheet show consistency when fully normalized. The sheet achieved by route B2 are Rp0.2 ≈513 MPa, Rm ≈646 MPa, elongation ≈17.2%, P10/400 ≈ 28.7 W kg−1, and B50≈1.64 T, achieving the best mechanical and magnetic properties in combination.

Micro Characterization of Hot-Rolled Plate of Nb-Bearing Grain-Oriented Silicon Steel.

In this study, niobium was added into grain-oriented silicon steels, four Nb-bearing hot-rolled bands with Nb content range from 0–0.025 wt% were prepared and a detailed study of the micro characterization (microstructure, texture and precipitates) of hot-rolled bands was carried out by various analysis methods, such as EBSD and TEM. The results indicate that the precipitates in Nb-free steel are MnS and AlN; however, in the Nb-bearing steel they are MnS, AlN and Nb(C, N). The precipitates are finer and more dispersed in Nb-bearing steel, and a stronger pining force was obtained, which contributes to the finer microstructure and less recrystallization fractions of the hot-rolled bands. A larger volume fraction and stronger intensity of Goss texture is presented in steel with 0.025 wt% Nb due to the effective inhibiting effect. However, it has little effect on the changes of microstructure and texture when the Nb content is more than 0.009 wt%.

Texture Development During Cold Rolling of a β-Ti Alloy: Experiments and Simulations

Microstructure evolution and texture development during cold rolling of a Ti15333 alloy were systematically investigated in the present work. Texture was simulated using mean-field [Visco-Plastic Self-Consistent (VPSC) and Taylor] models. Evolution of crystallographic texture was also simulated using the Visco-Plastic Fast Fourier Transform (VPFFT) model. The as-received samples (in the hot-forged and hot-rolled condition) were cold rolled unidirectionally up to 20, 40, 60 and 80 pct thickness reductions. Increase in the cold-rolling reduction resulted in changes in the crystallographic texture as well as grain morphology. The initial hot-rolled sample consisted of in-grain shear bands that were aligned approximately ± 35 to 40 ° with respect to the sample rolling direction. Shear band density gradually increased with the increase in cold-rolling reduction, and these bands usually represent narrow zones of intense strain. α (RD//〈110〉) and γ (ND//〈111〉) fibers were observed in all the cold-rolled samples. The volume fraction of both these fibers was found to be highest for the 80 pct deformed sample. For mean-field simulations, the normalized difference of the texture index (normalized TIdiff) was found to be a good criterion to represent the match between the simulated and experimental texture. The affine model (VPSC) was found to give a good match with the experimental texture compared to the Taylor models. The γ-fiber and α-fiber were always overestimated in mean-field VPSC simulations. Extensive shear band formation could be the possible reason for mismatch between the simulated and experimental texture. For VPFFT simulations, the general texture evolution involved the intensification of the γ-fiber and α-fiber texture. Simulated texture was reasonably well predicted quantitatively with VPFFT, analyzed based on the volume fraction of the different texture fibers/components.

Approach to oriented grain growth accounting during aluminum alloys recrystallization simulation

The study focuses on the new approach to orientated growth modeling for aluminum alloys. Avrami equation for JMAK phase transformation model was applied to derive the relationship for texture volume fractions change during recrystallization. Two phases, recrystallized and non-recrystallized, are considered for Avrami equation derivation. Two recrystallized volume types were addressed: first, containing cube-oriented nuclei, growing with β-fiber orientations, second, containing the remaining nuclei, including cube-oriented nuclei without the boundary with β-fiber texture orientation material. The linear rate of cube-oriented volume nuclei migration k times exceeded the growth rate of the volume, identified as G and containing the other grains. The obtained relationships were integrated in the previously developed unique model of texture evolution during aluminum alloys thermomechanical treatment. It was used to simulate 3104 alloy commercial rolling in the continuous rolling mill and subsequent self-annealing in a coil. Modeling demonstrated, that accounting for grain orientated growth enabled improving the accuracy of texture composition calculation, its cube constituent, in particular.

Influence of temperature on microstructure, crystallographic texture and mechanical properties of EN AW 6016 alloy during plane strain compression

The use of Al-Mg-Si alloys has increased significantly in automobile and aerospace industries during the past few decades, and improving the formability of the alloy has always been under focus for various applications. Plane strain compression (PSC) tests have been conducted for EN AW 6016 naturally aged (T4) alloy at different temperatures (room temperature, 150 °C and 250 °C), at a particular strain rate (0.1 s−1). The samples exhibited a decreasing pattern of flow properties (yield strength and work hardening rate) and increasing anisotropy with temperature. The reasons for the changes in flow behaviour with temperature were explained with the help of finite element modelling (FEM). Work hardening behaviour at different stages of stress was investigated and correlated with the microstructure. Microstructural characterization has been performed using electron backscattered diffraction (EBSD), and scanning electron microscopy (SEM) based Gallium Enhanced Microscopy (GEM) techniques with an aim to reveal the substructure development due to imposed deformation at different temperatures. Calculation of macro-texture was performed using X-Ray Diffraction (XRD) technique in order to observe the changes in crystallographic texture before and after deformation. A mathematical comparative analysis indicates the contribution of different texture components towards the variation in flow properties. Considerable increment in volume fraction of Goss texture at 250 °C has been found to have a significant impact on formability.

The microstructure, texture evolution and plasticity anisotropy of 30SiMn2MoVA high strength alloy steel tube processed by cold radial forging

Cold radial forging is an efficient and high-precision process for producing rotary parts such as axles and gun barrels, etc. 30SiMn2MoVA high strength alloy steel is a kind of fine pearlite steel usually used for moulds and barrels. This work focused on the effect of the cold radial forging on the microstructure, texture evolution and plasticity anisotropy of forged steel tube under different forging reductions. The results suggest that most banded structures that are parallel to the axial direction are developed by the radial forging process. The grains are elongated and refined after forging. The increase of dislocation density with the increase of deformation is the reason for grain refinement. Refined grains and high dislocation lead to high strength. Meanwhile, anisotropy was obvious and was exacerbated by the growth of the forging deformation. The circumferential strength and elongation are inferior to the axial. With the increasing of forging ratios, the α-fiber texture is well developed. The relationship between the volume fraction of texture and plastic strain was built. It can predict the volume fractions of the main texture components in the cold radial forged 30SiMn2MoVA steel tube. The Taylor factors of the main orientations were calculated. The {111}<011>(γ-fiber), {110}<110>, {111}<110>(α-fiber), {114}<110>, {112}<110> and {223}<110> texture components help to enhance the axial yield strength. Comparing the ratio of the axial average Taylor factor and the circumferential average Taylor factor with the yield strength ratio, it is found that yield strength anisotropy is not well predicted only taking into account the crystal texture. The effect of banded structures on the strength should also be considered.

Influence of Rolling Process on Deformation and Recrystallization Texture of Ni-Cr-Mo Alloy Tape

For the attainment of a sharp cube-textured tape, the influence of deformation degree and rolling regime on deformation and recrystallization texture was studied. Low Curie temperature ternary alloy of Ni-7.9at.%Cr-1.8at.%Mo ingot was prepared by using cold crucible induction levitation melting, and a final thickness of 80-μm textured tape was obtained after forging, hot rolling, cold rolling and recrystallization annealing. The results showed that with an increase in rolling reduction from 50 to 99.5%, S + C-type textures were enhanced and B + G-type textures were reduced, and the volume fraction of cube texture in recrystallized tape was increased; a two-stage rolling obviously refines the initial microstructure for the second large reduction cold rolling and thus slightly lowers the volume fraction of B texture component in the deformed matrix, leading to a high percentage of cube texture after recrystallization. The intermediate annealing in a two-stage rolling process reduces the grain size and mitigates the inhomogeneity of the microstructure.

Effect of cold rolling reduction on microstructure, mechanical properties, and texture of deep drawing dual-phase (DP) steel

In this study, the microstructure, mechanical properties, and texture of deep drawing dual-phase (DP) steel subjected to different cold rolling reductions were characterized via optical microscopy (OM), scanning electron microscopy (SEM), and x-ray diffraction (XRD) techniques. The results revealed that the microstructure of the steel is composed of ferrite and a small amount of martensite after cold rolling annealing. The ferrite grain size varied only slightly with the reduction. In addition, the orientation density along the γ orientation line increased continuously with increasing cold rolling reduction ratio. Similarly, the {112}〈110〉 and {223}〈110〉 components along the α orientation line and the adjacent {554}〈225〉 and {332}〈113〉 components were strongly developed. The ratio of the {111} plane texture volume fraction to that of the {100} plane texture, i.e., V{111}/V{100}, increased initially and then decreased, reaching the optimum value at 75% reduction. The maximum strength of the steel (i.e., 430 MPa) was realized at 55% reduction. However, the best elongation and r values (29.8% and 1.46, respectively) were obtained at 75% reduction.

Thermal stability of different texture components in extruded Mg–3Al–1Zn alloy

Abstract Grain growth can modify the texture orientation and the fraction of different texture component. The thermal stability of two texture component in an extruded magnesium AZ31 alloy was investigated. Three types samples with different texture distribution were prepared. The results show that normal grain growth takes place in the magnesium AZ31 alloy during annealing at 300 °C and 450 °C. But the grain growth does not lead to the strengthening of either texture component. Both the ⊥ED texture and //ED texture components show good thermal stability, without influence of the texture volume fraction. The two different texture component possess comparable boundary migration ability, so grains of the two texture component consume indifferently the other grains, or are equally consumed during annealing.

Effect of cold rolling reduction on microstructure, mechanical properties, and texture of deep drawing dual-phase (DP) steel

In this study, the microstructure, mechanical properties, and texture of deep drawing dual-phase (DP) steel subjected to different cold rolling reductions were characterized via optical microscopy (OM), scanning electron microscopy (SEM), and x-ray diffraction (XRD) techniques. The results revealed that the microstructure of the steel is composed of ferrite and a small amount of martensite after cold rolling annealing. The ferrite grain size varied only slightly with the reduction. In addition, the orientation density along the γ orientation line increased continuously with increasing cold rolling reduction ratio. Similarly, the {112}〈110〉 and {223}〈110〉 components along the α orientation line and the adjacent {554}〈225〉 and {332}〈113〉 components were strongly developed. The ratio of the {111} plane texture volume fraction to that of the {100} plane texture, i.e., V{111}/V{100}, increased initially and then decreased, reaching the optimum value at 75% reduction. The maximum strength of the steel (i.e., 430 MPa) was realized at 55% reduction. However, the best elongation and r values (29.8% and 1.46, respectively) were obtained at 75% reduction.

Influence of precipitate-assisted nucleation on the microstructure and mechanical properties of Al-Mg-Si-Cu-Zn alloys

ABSTRACTThe influence of precipitation on the recrystallization nucleation and mechanical properties of Al-Mg-Si-Cu-Zn alloys was investigated by means of tensile tests, SEM, TEM, XRD and EBSD. The results reveal that there are distinct contributions from the various precipitates that form during annealing and that these critically influence the evolution of microstructure and its associated texture, as well as mechanical behaviour. In contrast to alloy sheets A, B, and C annealed at a lower temperature or for a shorter time, the T4P alloy sheet D with an annealing at 450°C for 3 h not only possesses almost identical strength and elongation, but also a higher average r (0.659) and n (0.313) values, and also a lower Δr (0.091) value. After solution treatment, the four alloy sheets are comprised of equiaxed grains with somewhat different grain sizes and different textures, but texture volume fraction and grain size in alloy sheet D both are decreased due to the effect of precipitate-assisted nucleation during solution treatment. The corresponding nucleation and growth mechanisms of recrystallization grains were established and the relationship between textures and r value in the four alloy sheets was also analyzed on the basis of a Visco-plastic self-consistent (VPSC) model.

Texture Evolution and Its Effect on Fatigue Crack Propagation in Two 2000 Series Alloys

The texture evolution and fatigue crack propagation (FCP) of 2000 series alloys were investigated, respectively, by using scanning electron microscopy and x-ray diffraction. Results showed that the intensity change in different textures (such as Goss, Copper, S and Brass) abides by a linear evolution law, and a new model for texture evolution is proposed to predict the texture intensity during different heat treatments. With increasing annealing temperature, the FCP rate increased, but the damage tolerance decreased. The intensity of P texture was the key to affecting FCP rate and damage tolerance of the alloys. A new model based on the average grain diameter and P texture volume fraction was proposed to predict FCP rate and damage tolerance, and the predicted FCP rates agree very well with the experimental FCP rates of the alloys after different T83 treatments.

Local Deformation and Texture of Cold-Rolled AA6061 Aluminum Alloy.

Using cold rolling, we plastically deform AA6061 sheets at room temperature and investigate the variations of the microstructures, textures and local deformation of the cold-rolled AA6061 sheets as functions of thickness reduction (Δt/t0, t0 and t are the thicknesses of the AA6061 sheet before and after the cold rolling, respectively). The volume fraction of total deformation texture is relatively independent of the thickness reduction for Δt/t0 ≤ 30%, and becomes an approximately linearly increasing function of the thickness reduction for Δt/t0 > 30%. Increasing the thickness reduction causes the increase of the Vickers hardness of the cross-section of the cold-rolled sheets, which exhibits a similar increase trend to the volume fraction of total deformation texture for Δt/t0 > 30%. A simple relation between the Vickers hardness and the thickness reduction is established and is used to curve-fit the experimental results.