Effect Of Initial Texture Research Articles

Effect of initial texture on the formability of Zircaloy-4 sheet in stamping with FEM-VPSC modeling

Effect of initial texture on the formability of Zircaloy-4 sheet in stamping with FEM-VPSC modeling

Microstructural effects in rate-dependent responses of smooth and notched magnesium bars

We perform three-dimensional crystal plasticity simulations of smooth and notched bar geometries made of polycrystalline hexagonal close-packed material representing a magnesium alloy. The polycrystalline microstructure is explicitly resolved to investigate the combined effect of initial texture and grain size on the rate-dependent macroscopic responses and their micromechanical underpinnings under uniaxial and multiaxial stress states. The simulations reveal that in addition to the textural effect recently investigated by Ravaji et al. (2021), grain size plays an important role in the anisotropy of macroscopic responses. For a given texture, the lateral deformation anisotropy increases with grain size refinement for all strain rates considered here. The load-deformation responses exhibit a synergistic strengthening effect in microstructures with stronger initial textures and finer grain sizes, which is enhanced with increasing notch acuity. A transition from a conventional power-law type load-deformation response to a sigmoidal load-deformation response may occur, which depends on the imposed strain rate. It is a result of the interaction between textural weakening and grain size refinement that influence extension twinning together with an equitable landscape of the different slip mechanisms. We discuss possible implications of the net material plastic anisotropy due to texture and grain size on macroscopic failure using a micromechanical basis.

Effects of Initial Texture on the Formation of Deformation Twins in a Cu–Zn System Alloy

Effects of Initial Texture on the Formation of Deformation Twins in a Cu–Zn System Alloy

Tension-compression asymmetric functional degeneration of super-elastic NiTi shape memory alloy: Experimental observation and multiscale constitutive model

The functional degeneration of super-elastic NiTi shape memory alloy (SMA) rods is investigated in the cyclic tension-unloading and compression-unloading experiments. The results show that the functional degeneration exhibits a strong tension–compression asymmetry, which originates from the initial 〈111〉 and 〈110〉 mixed textures along the axial direction of the rods, the polarity of martensite transformation, and the complex interaction between martensite transformation and dislocation slipping. Moreover, the dependence of functional degeneration on the applied stress level is discussed. To understand and predict the effect of initial texture on the cyclic deformation of polycrystalline NiTi SMA, a multiscale constitutive model is constructed at finite deformation. At the mesoscopic scale, two major inelastic deformation mechanisms, i.e., the transformation between austenite and martensite phases and the transformation-induced plasticity caused by the strain mismatch at the austenite–martensite interface, are considered. The total deformation gradient is multiplicatively decomposed into the martensite transformation, transformation-induced plasticity and elastic parts. The deformation gradient parts at the mesoscopic scale are obtained by upscaling these physical quantities at a smaller spatial scale (i.e., the microscopic scale). The proposed model is formulated within the framework of irreversible thermodynamics. The driving forces for martensite transformation and transformation-induced plasticity are derived according to the established Helmholtz free energy and Clausius-Duhem inequality. The complex interaction between martensite transformation and dislocation slipping, and the forward/reverse inheritance of dislocations caused by the moving austenite–martensite interfaces are considered. To calculate the overall cyclic responses of polycrystalline NiTi SMA at the macroscopic scale, the developed constitutive model is implemented into the finite element software ABAQUS/Explicit using a user-defined material subroutine. A polycrystalline representative volume element is constructed by introducing the initial 〈111〉 and 〈110〉 mixed textures observed in the experiment. By comparing the simulated results with the experimental data, the capability of the proposed model to predict the texture-induced tension–compression asymmetric functional degeneration is verified, and the influence of texture type on the cyclic deformation is discussed.

The Effect of Initial Texture on the Plastic Deformation of Gradient Aluminum.

The effect of specific processing-induced surface textures in gradient aluminum has not yet been investigated. A dislocation-based multi-scale framework is employed to explore the influence of various initial shearing textures and the depth from the surface of the region featuring each texture on the macroscopic behavior of gradient aluminum. By assigning different textures to the same grain size gradient aluminum sample, the initial texture was found to significantly affect the plastic deformation and macroscopic behavior of gradient aluminum. Specifically, the {111} texture can enhance the strength-ductility synergy, and this effect is dependent on the depth from the surface where the texture is located. This texture can lead to a slow stress/strain gradient in the assigned texture region and a sharp stress/strain gradient in the grain size gradient region connecting this region with the coarse grain region. Particularly, the sharp stress/strain gradient can result in extra strengthening by adjusting the stress/strain localization. These findings provide valuable insights for the design and optimization of surface textures in gradient aluminum.

The effect of initial texture on multiple necking formation in polycrystalline thin rings subjected to dynamic expansion

In this paper, we have investigated, using finite element calculations, the effect of initial texture on the formation of multiple necking patterns in ductile metallic rings subjected to rapid radial expansion. The mechanical behavior of the material has been modeled with the elasto-viscoplastic single crystal constitutive model developed by Marin (2006). The polycrystalline microstructure of the ring has been generated using random Voronoi seeds. Both 5000 grain and 15000 grain aggregates have been investigated, and for each polycrystalline aggregate three different spatial distributions of grains have been considered. The calculations have been performed within a wide range of strain rates varying from 1.66⋅104s−1 to 3.33⋅105s−1, and the rings have been modeled with four different initial textures: isotropic texture, 001∥Θ Goss texture, 001∥ R Goss texture and 111∥ Z fiber texture. The finite element results show that: (i) the spatial distribution of grains affects the location of the necks, (ii) the decrease of the grain size delays the formation of the necking pattern and increases the number of necks, (iii) the initial texture affects the number of necks, the location of the necks, and the necking time, (iv) the development of the necks is accompanied by a local increase of the slip activity. This work provides new insights into the effect of crystallographic microstructure on dynamic plastic localization and guidelines to tailor the initial texture in order to delay dynamic necking formation and, thus, to improve the energy absorption capacity of ductile metallic materials at high strain rates.

Effect of Texture and Temperature on Strain‐Induced Martensitic Transformation in 304 Austenitic Stainless Steel

The austenitic stainless steel's remarkable mechanical properties are caused by twinning‐induced plasticity and transformation‐induced plasticity mechanisms. Numerous studies focus on stacking fault energy's effect, which is affected by various factors, to interpret and control these mechanisms. However, crystallographic orientation is also an important parameter for mechanical properties in metals. This study compares the mechanical properties and microstructural features of 304 austenitic stainless steel, focusing on the effect of initial texture and deformation temperature. Microstructural characterization is identified by an interrupted tensile test based on strain, tensile direction, and temperature conditions, and X‐ray diffraction and electron back‐scattered diffraction analysis are performed. The results show that the mechanical features and strain‐induced martensitic transformation rate depend on the tensile directions. In addition, this trend is maintained irrespective of the temperature conditions. The attribute reason is that the difference in the Taylor factor and the formation rate of the deformed band structure is induced by the initial crystallographic orientations. Moreover, a decrease in temperature significantly increases the dislocation densities and abundant twins and transformed martensites formation. Furthermore, the yield and tensile strengths are enhanced while the elongation decreased with the tensile strains.

Effects of Initial Texture on the Formation of Deformation Twins in a Cu–Zn System Alloy

Effects of Initial Texture on the Formation of Deformation Twins in a Cu–Zn System Alloy

3D simulation of texture evolution induced grain coarsening in FCC polycrystals during severe plastic deformation

In the present work, results obtained in 3D polycrystal simulations are reported on the coalescence effect of neighbouring grains due to texture evolution. A 3D cellular automaton model was developed for this purpose, which permits to take into account the effect of topology on coalescence. The grains constituting the polycrystal were divided into voxels to have realistic representations of grain shapes. The Taylor polycrystal plasticity approach was applied to calculate the orientation change for each voxel. When the disorientation angle between neighbour voxels belonging to different grains was less than 5°, the voxel volume was reallocated to the neighbouring grain. For a random initial texture, after a shear strain of 6, the relative volume that was re-assigned between neighbours was 29.7%, which is not negligible. The effect of initial texture and topology was also investigated. The 3D morphologies of some typical coarsening grains were monitored to illustrate the simulation results.

Effect of twinning on the yield surface shape of Mg alloy plates under in-plane biaxial loading

The EVPSC-TDT model is first employed to investigate the yield behavior of a strongly basal textured Mg alloy plate under biaxial loading. The material parameters are calibrated according to experimental uniaxial tension and compression along the rolling and plate normal directions. The EVPSC-TDT model with the calibrated parameters is then employed to conduct various biaxial loadings under plane stress condition. The predicted yield surface and its evolution match well with the experimental data. The shape change of the yield surfaces in all four quadrants is interpreted according to the activated deformation modes. Compressive twinning weakens the work hardening behavior in the first quadrant of the yield surface at relatively large plastic strain level, while tensile twinning plays an important role in determining the shape of the second, third and fourth quadrants of the yield surface. A turning point corresponding to pure shear loading is observed in the second quadrant of the yield surface which is caused by the transition of activated deformation modes from basal slip and tensile twinning to non-basal slip. In addition, the effect of initial texture on the shape of the yield surface of Mg alloy plates has been briefly investigated.

Dynamic corrosion behavior of AZ80 magnesium alloy with different orientations in simulated body fluid

Two specimens were prepared along the normal (ND) and transverse (TD) directions of the AZ80 magnesium alloy rolled sheet, respectively, and the other specimen was prepared along the normal direction at 45° (ND45). Three specimens (ND, ND45 and TD) were immersed in dynamic immersion equipment for in-situ electrochemical test. Electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used to investigate the static and dynamic corrosion behavior of the specimens in simulated body fluid (SBF). The results indicated that the specimens with different orientations exhibited anisotropy of corrosion performance. The electrochemical corrosion resistance of the specimens decreased in the following order: TD > ND45 > ND. The electrochemical corrosion resistance of the specimens decreased with increasing flow rate. The specimens immersed in SBF solution suffered localized corrosion, and the corrosion degree at the edge position of the specimen was higher than that at the middle position in dynamic environment. Computational fluid dynamics (CFD) simulations showed that with the increase of flow rate, the increase of shear stress and mass transfer coefficient led to the intensification of localized corrosion. The effect of initial texture and flow rate on the corrosion behavior of magnesium alloy was discussed.

Effect of Initial Texture on the Evolution of Microstructure and Texture During Rolling of Commercially Pure Titanium at Room and Cryogenic Temperature

The evolution of texture and microstructure of commercially pure titanium during unidirectional rolling at room and cryogenic temperature was studied for two different initial orientations, namely RD (rolling direction)-split basal (BA orientation) and prismatic-pyramidal (PP orientation) till 90 pct rolling reduction. Effect of micro-mechanisms of deformation by slip and twinning on texture evolution and grain fragmentation was studied by employing characterization tools like bulk texture measurement using X-ray diffraction and electron back scatter diffraction. Both orientations yield split TD (transverse direction) texture for 90 pct rolling reduction at both the temperatures. Orientation BA showed severe twinning that saturated at deformation of 50 pct followed by slip dominated deformation, while orientation PP showed slip dominated deformation with marginal twinning throughout the rolling reduction at room temperature. Profuse twinning led to homogeneous grain refinement in orientation BA, while orientation PP showed heterogeneous grain refinement due to absence of twinning in some grains at the final stage of deformation. Rolling at cryogenic temperature enhances grain refinement due to extensive twinning that leads to weakening of texture in BA orientation and increase in intensity of texture for PP orientation compared to room temperature rolling. The evolution of microstructure and texture contributed to similar hardness for 90 pct room and cryogenic temperature rolled BA orientation, while 90 pct room temperature rolled PP orientation showed lower hardness.

Effect of initial texture on the {10–12} twinning variants selection mechanism in AZ31 magnesium alloy

The influence of the initial texture of the {10–12} twinning variants selection mechanism of the magnesium alloy was investigated using the compression test, the EBSD technology, the trace method, the orientation rotation method, and the Schmid’s law. Results show that various {10–12} twin patterns are observed in the AZ31 E90 sample subjected to compression. In the multi-twins inside a grain pattern, the high Schmid factor (SF) variant is activated first to coordinate the externally imposed strain, and the ortho-position (OP) variant with the best strain compatibility is activated. Typical case of paired twins in two neighboring grains usually have high SF, and the activation of corresponding variants follows the Schmid’s law. When E45 sample is compressed, the of a pair of relative variants among the six twin variants in the crystal is very large and favorable for local strong basal texture formed by the two adjacent grains for the twin-transfer phenomenon. When E0 sample is compressed, the activation of the corresponding variants follows the Schmid’s law and is linked to the stress fluctuation at the grain boundary.

Effects of initial texture on deformation behavior during cold rolling and static recrystallization during subsequent annealing of AZ31 alloy

This study demonstrates that the initial texture of Mg alloy significantly affects the microstructure developed during cold rolling and the recrystallization behavior during subsequent annealing. In a sample with a texture oriented toward the normal direction (ND sample), thick and large-sized shear bands are intensively formed during cold rolling and the deformation is strongly localized along these bands. In contrast, in a sample with a texture oriented toward the transverse direction (TD sample), many {10-12} twins are formed at the early stage of cold rolling, and then, numerous small-sized shear bands are formed in these twins. Results of nanoindentation tests reveal that the cold-rolled ND sample has internal strain energy that is substantially concentrated along the shear bands, whereas the cold-rolled TD sample has a large amount of internal strain energy that is homogeneously distributed throughout the material; this latter behavior is strongly related to the extensive {10-12} twinning and the resultant microstructural variations in the TD sample. During subsequent annealing, recrystallization occurs locally along the shear bands in the ND sample, which leads to the formation of a bimodal grain structure comprising fine recrystallized grains and coarse unrecrystallized grains. In contrast, during subsequent annealing of the TD sample, static recrystallization occurs homogeneously throughout the material, which results in the formation of a uniform grain structure that mostly comprises equiaxed recrystallized grains.

Effect of Initial Texture on the Development of Goss Orientation of Asymmetrically Rolled Steel Sheets

Effect of Initial Texture on the Development of Goss Orientation of Asymmetrically Rolled Steel Sheets

A comparative study between {11−22} twinning and {10−12} twinning variant selection mechanisms during uniaxial compression in pure titanium

The effect of initial texture on the twinning behaviors of pure titanium during uniaxial compression was investigated by electron backscattered diffraction (EBSD) technology. The {11−22} and {10−12} twinning variant selection behaviors were investigated by the Schmid factor (SF), strain compatibility factor (m′) and twinning strain tensor. For {11−22} contraction twins, multiple twin variants are more likely to form within a grain. For {10−12} extension twins, however, single variant is usually observed within one grain. The variant selection of {10−12} twinning is more favorable to follow the SF law than that of {11−22} twinning. However, both {11−22} twinning and {10−12} twinning variant selection behaviors can be well explained by the twinning strain tensor. The activated {11−22} twinning or {10−12} twinning variants can well accommodate the deformation along the compression direction. For intragranular cases, when multiple twins are generated within a grain, most of the activated variants have high SF values, and both {11−22} twinning and {10−12} twinning activities show stronger orientation dependence. For intergranular twin pairs, the strain compatibility is related to their formation sites. The twin pairs forming in the common boundaries of the two grains have good strain compatibility. However, twin pairs at those triple junctions show poor strain compatibility.

Effects of initial texture on the three-dimensional creep anisotropic behaviors of dilute Mg–Y binary alloy sheets

The effects of initial texture on the three-dimensional creep anisotropic behaviors of dilute Mg–2Y(wt%) binary alloys were investigated in this study. Two kinds of sheets were used: one had a concentrated texture (CT sample) and the other had a split texture (ST sample). According to the compressive directions and conventional orthogonal coordinate system for sheet, the samples were named as CT-RD, CT-TD, CT-ND and ST-RD, ST-TD, ST-ND. Compressive creep tests were conducted at 493 K and applied stresses ranged from 40 to 100 MPa. The results showed that both CT and ST samples had evident three-dimensional creep anisotropy. Specifically, the creep resistance was highest in CT-ND sample, followed by ST-ND, ST-TD, CT-TD, CT-RD samples, and lowest in ST-RD sample. Next, the dominant creep mechanisms in all samples were strictly investigated using various characterization methods. For CT-RD and CT-TD samples, the dominant creep mechanisms were similar, including cross-slip and twinning. For CT-ND sample, the dominant creep mechanisms were dislocation climb and pyramidal <c+a> slip. For ST samples, a variety of creep mechanisms were detected, ranging from heavy basal slip to easy activations of cross-slip and twinning. A little bit dislocation climb and pyramidal <c+a> slip acted as plastic accompanying roles in ST samples. Furthermore, the variation of initial texture types led to the variations of dominant creep mechanisms and the different three-dimensional creep anisotropic behaviors. The rank of deteriorating creep resistance was revealed as basal slip > cross-slip > twinning > dislocation climb > pyramidal slip. Finally, it is proposed that future work on the enhancement of creep resistance of Mg alloys with rare earth addition should focus on the inhibition of basal slip and cross-slip.

Twin-induced stability and mechanical properties of pure magnesium

In the present study the effect of initial texture and annealing temperature on the microstructure and mechanical anisotropy of pure magnesium has been investigated. Evolution of microstructure after annealing was analysed by optical microscopy and SEM/EBSD. Magnesium samples with different initial textures were deformed at room temperature at a strain rate equal to 10−3 s−1 followed by subsequent annealing at 473 K and 673 K. The texture evolution, work hardening and microstructure have been examined after annealing treatment. It was found that the initial texture affects the main deformation mode as well as influences the texture upon annealing. During compression, samples deform by twinning, while slip becomes the dominant deformation mode for samples having c-axis perpendicular to the extrusion direction. Moreover, it was shown that the recrystallization temperature is critical for texture evolution and mechanical properties of the annealed magnesium samples. Annealing at 473 K does not initiate recrystallization in samples exhibiting twins whereas samples without twins undergo recrystallization strengthening particular texture components in ODF sections. However, annealing at 673 K leads to a strong grain growth lowering the yield strength of the material. It was shown that an intensive twinning can stabilize the microstructure of pure magnesium and improves its mechanical properties up to 473 K.

Microstructure and texture evolution of AZ31 Mg alloy after uniaxial compression and annealing

The effect of initial texture on the microstructure and texture evolution of as extruded AZ31 alloy after hot uniaxial compression at 430 °C and subsequent annealing at 450 °C for 72h has been investigated using electron backscatter diffraction. Samples were machined from the extruded block in such orientations that the compression axis, CD, was parallel (CD0ED) or perpendicular (CD90ED) to the initial extrusion direction, ED, respectively. Results show that the deformation microstructure for both samples was characterized by equiaxed grains that resulted from dynamic recrystallization. Annealing at 450 °C for 72 h led to the increase of grains size to 28 and 25 µm for CD0ED and CD90ED samples, respectively. A random deformation texture was developed in CD0ED sample while the deformation of CD90ED developed typical (0002) basal texture. The deformation textures of both samples were retained after subsequent annealing at 450 °C for 72 h. The flow behavior was affected by the initial texture. The CD0ED sample showed the highest work hardening. These evolutions were explained in term of the activation and suppression of basal, non-basal slip and mechanical twinning.

Effect of initial texture on deformation-induced grain growth in pulsed electrodeposited microcrystalline copper

ABSTRACTOwing to the presence of large fraction of grain boundaries, deformation-induced grain growth is commonly observed in fine-grained electrodeposited metals. Here we demonstrate that microcrystalline copper (d∼1–10 µm) with different textures produced by electrodeposition exhibit significant deformation-induced grain growth in tension by coalescence along with twin boundary migration and detwinning. Oriented growth with the formation of a cube texture was noted in the deformed samples. There was an increased fraction of twin boundaries with large angular deviation from Brandon's criterion during deformation.