Deformation Texture Components Research Articles

Twinning effects in deformed and annealed magnesium–neodymium alloys

Hot rolled Mg–1wt% Nd alloy with a weak {0001}<112¯0> basal texture was subjected to plane strain compression (PSC) at room temperature. Compressive loads were imposed parallel to the in-plane (IPC) and through-thickness (TTC) directions of the rolled plate in order to engage different types of deformation twins. PSC was conducted up to 6% and 12%, and the deformed specimens were subsequently annealed at different elevated temperatures to investigate recovery and recrystallization in the formerly developed twins. Deformation and annealing textures and microstructures were characterized using X-ray diffraction, optical microscopy and electron backscatter diffraction techniques. Deformation under IPC and TTC displayed competitive activation of extension and contraction twinning, supplemented by homogenous dislocation slip. Deformation in IPC up to 6% witnessed equal activation of both aforementioned twinning modes that gave rise to soft and hard texture components. TTC up to 12% exhibited a less regular basal-type deformation texture, characterized by a large outspread in the rolling direction, and an asymmetrical splitting of the basal poles around the transverse direction by about −5° and +25°. Texture evolution during annealing was associated with general texture weakening, preserving the primary deformation texture components at relatively low annealing temperatures with no recrystallization (300°C). Presence of strong impurity drag and particle pinning delayed the onset of recrystallization till 325°C for TTC and 350°C for IPC specimens, which took place preferably inside compression and double twins. Related recrystallized grains possessed a high Schmid factor (SF) for basal slip, and were larger and more prevalent on average than competing low SF grains related to extension twins or the matrix. Re-dissolution of precipitates at 450°C triggered grain growth that led to strong evolution of orientations associated with compression and double twins as a result of a grain size advantage that emerges during recrystallization.

Recrystallization behavior of a high-manganese steel: Experiments and simulations

Abstract The thermal treatment of a 30% cold-rolled Fe–28Mn–0.28C Twinning-Induced Plasticity (TWIP) steel was investigated. The low degree of rolling served to exclude the effect of shear banding but to capture the characteristic texture evolution. A detailed microstructure and texture characterization was performed by means of SEM/EBSD, X-ray texture analysis, and hardness measurements. Specifically, the dislocation density distribution was computed using a Crystal Plasticity Finite Element Method (CP-FEM) framework and the primary recrystallization was modeled by means of a Cellular Automaton (CA) approach. The macrotexture of the recrystallized state was controlled by (i) retainment of the deformation texture components during nucleation due to oriented nucleation and (ii) the formation of new orientations by recrystallization twinning. The nucleation of new grains occurred heterogeneously at grain boundaries. The experimental results were used as input data for simulations. The results from the CP-FEM simulations in the form of orientation-resolved dislocation densities and the orientation and density of recrystallization nuclei extracted from SEM/EBSD measurements were directly transferred into a 3D CA for the simulation of primary recrystallization. The results substantiated that the consideration of realistic simulation scenarios in terms of microstructural inhomogeneity and annealing twin formation is essential for an accurate prediction of the recrystallization behavior of the investigated high-manganese steel.

Mechanical anisotropy and microstructural changes during cryorolling of Al–Mg–Si alloy

Rolling was performed on Al–Mg–Si alloy sheets to true strain values of 0.69 and 1.38 at both room temperature and at cryogenic (liquid nitrogen) temperature and the influence of rolling temperature on microstructure and mechanical properties was studied. At both the reductions, cryorolled samples exhibited enhanced hardness and strength compared to room temperature rolled samples. The enhanced properties of cryorolled samples are attributed to the high dislocation density, increased microstrain and a reduced crystallite size compared to room temperature rolled samples. Besides, at high true strain condition, anisotropy behaviour was studied and correlated with X-ray bulk texture components. Evaluation of the percentage volume fraction of individual texture components revealed that cryorolled samples exhibited ~16% and ~33% increase in S and brass deformation texture components, respectively compared to room temperature rolled samples. Cryorolled samples also showed an enhanced texture index value compared to room temperature rolled samples.

Assessment of crystal plasticity finite element simulations of the hot deformation of metals from local strain and orientation measurements

Simulations of the deformation of microstructures at high homologous temperatures have been carried out using a Crystal Plasticity Finite Element (CPFE) model to predict texture and grain structure deformation in Face-Centred-Cubic (FCC) metals deformed under conditions representative of hot forming operations. Results show that the model can quantitatively predict the location and intensity of the main deformation texture components of a AA5052 aluminium alloy deformed at 300 °C under Plane Strain Compression (PSC). Simulations also reasonably predict the range of strain values measured using microgrids in the microstructure of a Fe-30wt%Ni alloy deformed at 1000 °C using a new experimental procedure. However, the model fails to reproduce accurately intra-granular strain distribution patterns. Results at room temperature, after a tensile test carried out inside a Scanning Electron Microscope (SEM) on the same model alloy, show a much closer match between simulation and experimental results. Despite discrepancies for some local deformation features, the model predicts the formation of intense deformation bands running at 45° with respect to the tensile axis and located along the same grain boundaries as in the experiment. Results, therefore, highlight the limitations of deterministic CPFE simulations for situations where the grain size to sample thickness ratio is small and for which the sub-surface grain geometry strongly affects surface strains. They also show that reliable predictions of the statistical response of a polycrystalline aggregate can be obtained for the hot deformation of metals which controls microstructure evolution during the processing of metals.

Twin recrystallization mechanisms in magnesium-rare earth alloys

Binary Mg-1wt.% Gd and Mg-1wt.% Ce wrought alloys, with basal type starting texture, are subjected to plane strain compression. Specially oriented specimens invoking c-axis extension (In Plane Compression) and c-axis compression (through thickness compression) were deformed to 6% and 13% respectively. Deformation in Mg-1Gd under in plane compression (IPC) led to evolution of sharp ‘prismatic fiber’ texture, whereas a weak basal texture was witnessed for Mg-1Ce. In case of through thickness compression (TTC), Mg-1Gd gave rise to a split basal component, whereas Mg-1Ce resulted in a weak basal component with large off-basal spread. Microstructurally, Mg-1Gd displayed unequivocal activation of both {101¯2} tension twinning and {101¯1} compression twinning during IPC, while profuse {101¯1} compression twinning for the TTC mode. Majority of the compression twins underwent second generation {101¯2} tension twinning to give rise to {101¯1}–{101¯2} double twins. Compression and double twinned regions showed strong slip activity leading to the formation of fine recovered sub-structure. On the contrary, Mg-1Ce exhibited a conventional deformation response with twinning being predominantly of {101¯2} tension type. Annealing led to preservation of the deformation texture components along with strong texture weakening. Recrystallization in Mg-1Gd commenced discontinuously in compression and double twins, which at higher temperatures showed favorable growth behavior consuming the still deformed matrix and tension twins. Mg-1Ce displayed continuous recrystallization marked by recovery and growth of orientationally soft tension twins along with nucleation in the vicinity of particles.

Evolution of texture and its influence on the failure of components in some aluminium alloys

This paper describes the evolution of crystallographic texture in three of the most important high strength aluminium alloys, viz., AA2219, AA7075 and AFNOR7020 in the cold rolled and artificially aged condition. Bulk texture results were obtained by plotting pole figures from X-ray diffraction results followed by Orientation Distribution Function (ODF) analysis and micro-textures were measured using EBSD. The results indicate that the deformation texture components Cu, Bs and S, which were also present in the starting materials, strengthen with increase in amount of deformation. On the other hand, recrystallization texture components Goss and Cube weaken. The Bs component is stronger in the deformation texture. This is attributed to the shear banding.In-service applications indicate that the as-processed AFNOR7020 alloy fails more frequently compared to the other high strength Al alloys used in the aerospace industry. Detailed study of deformation texture revealed that strong Brass (Bs) component could be associated to shear banding, which in turn could explain the frequent failures in AFNOR7020 alloy. The alloying elements in this alloy that could possibly influence the stacking fault energy of the material could be accounted for the strong Bs component in the texture.

Microtexture of constituent phases in a heavily warm- rolled and annealed duplex stainless steel

Evolution of microtexture during isothermal annealing of a heavily warm-rolled Fe- 0.08%C-24.18%Cr-10.5%Ni duplex stainless steel (DSS) having approximately equal volume fraction of ferrite and austenite was investigated in the present work. The DSS was warm-rolled to ∼90% reduction in thickness at three different temperatures, namely, 225°C, 425°C and 625°C followed by isothermal annealing at 1175°C for different length of time. Austenite showed pure metal or copper type texture at different warm-rolling temperatures. In contrast, the texture of ferrite in different warm-rolled DSS revealed the presence of RD (RD//<110>) and ND (ND//<111>) fibers. The annealing texture of austenite showed retention of the deformation texture components while ferrite revealed strong RD-fiber.

Evolution of microstructure and crystallographic texture in severely cold rolled high entropy equiatomic CoCrFeMnNi alloy during annealing

An equiatomic FCC CoCrFeMnNi high entropy alloy (HEA) was heavily cold rolled up to 90% reduction in thickness followed by isochronal annealing for 1 hour at temperatures ranging between 700°C to 1100°C. A strong brass texture was observed in the cold-rolled condition indicating the low stacking fault energy of the material. A fine stable microstructure was observed during annealing at low temperatures. The recrystallization texture was characterized by the presence of deformation texture components, in particular, the α-fiber (ND//<110>), S ({123} <634>) and the typical brass recrystallization texture component ({236} <385>). Annealing twins were shown to have important effect on the formation of annealing texture.

Influence of intermediate annealing on the microstructure and texture of Ni-9.3at%W substrates

The effects of intermediate annealing (IA) on the microstructure and texture of Ni-9.3at%W substrates have been investigated by using electron backscattering diffraction and X-ray diffraction. Results suggest that IA can optimize the homogeneity of deformation microstructure. Higher IA temperatures (without undergoing recrystallization during IA) will increase the copper-type components of deformation texture and improve the content of cube texture after recrystallization. Sharp cube texture (97.2%) can be obtained at the optimum IA temperature of 650°C. The mechanism underlying the transition of deformation texture can be interpreted as that IA increases the dislocation slipping ability and suppresses the twinning deformation of Copper orientation in the subsequent rolling process. The observed strengthening of cube texture as a result of IA treatment is presumably attributed to the reduction of noncube nucleation and the optimization of preferential growth surrounding the cube nuclei.

Effect of texture evolution on mechanical properties of near eutectic Al–Si–Mg alloy with minor addition of Zr/V during hot extrusion

Texture evolution of as-extruded near eutectic Al–Si–Mg alloy with minor addition of Zr or V was studied by electron backscatter diffraction (EBSD), and the tensile properties were tested. To some extent, addition of 0.1% Zr could impede the recrystallization operation of near eutectic Al–Si–Mg alloy during hot extrusion. Addition of 0.1% V exhibits very strong inhibitory effect on recrystallization, that the texture of 4# alloy is mainly composed of deformation texture component of Brass {110}〈112〉, which may contribute to the excellent combined properties of ultimate strength (UTS), yield strength (YS) and elongation. The impact of Zr addition on the tensile properties is not as considerable as that of V addition.

Evolution of Microstructure and Texture during Isothermal Annealing of a Heavily Warm-rolled Duplex Steel

The evolution of microstructure and texture during isothermal annealing of a heavily warm-rolled duplex steel (DSS) was studied. For this purpose a DSS steel was hot rolled, homogenized at 1448 K and subsequently warm-rolled to 90% reduction in thickness at 698 K and 898 K. This was followed by isothermal annealing at 1448 K for different time intervals up to 7200 seconds. Lamellar microstructure with alternate arrangement of deformed ferrite and austenite bands was observed in the as warm-rolled condition. The ferrite in DSS warm-rolled at 698 K showed much stronger α-fiber (Rolling direction (RD)//<110>) than γ-fiber (Normal direction (ND)//<111>) as compared to the ferrite in DSS warm-rolled at 898 K. The austenite in warm-rolled DSS showed a predominantly pure metal (or copper type) texture. Upon annealing the lamellar morphology of the as warm-rolled structure transformed into a bamboo type morphology for short annealing time but finally broke down with increasing isothermal annealing time due to mutual interpenetration of the two phases. Retention of deformation texture components and presence of annealing twins in austenite indicated discontinuous recrystallization. Despite differences of texture in the as warm-rolled condition the ferrite in annealed DSS showed much stronger α-fiber as compared to γ-fiber due to strong recovery behavior of ferrite during annealing. The texture evolution in the two phases was not affected by the presence of the other phase while grain growth was significantly restricted due to the presence of the other phase.

Microstructure and texture evolution during annealing of equiatomic CoCrFeMnNi high-entropy alloy

• Recrystallization texture in high entropy alloys is reported for the first time. • The texture is compared to other low SFE alloys e.g. TWIP and austenitic steels. • Great resistance to grain coarsening during recrystallization. • Retention of deformation texture components during annealing like TWIP steels. • Stronger S than Brass and Goss components unlike TWIP and austenitic steels. Evolution of microstructure and texture after heavy cold rolling and subsequent annealing in a wide temperature range was first studied in an FCC equiatomic CoCrFeMnNi high-entropy alloy (HEA). Development of a submicron-cell structure and a strong brass-type texture was observed after 90% cold rolling. An ultrafine microstructure having average recrystallized grain size ∼1 μm with profuse annealing twins was observed after annealing at 650 °C. Remarkable resistance against grain coarsening was observed at least up to 800 °C. The mechanisms for these features were closely related with the distinct whole-solute matrix in HEAs. The recrystallization texture was characterized by the retention of deformation texture components similar to those of TWIP and 316 stainless steels. But notable differences exist. The S ({1 2 3}〈6 3 4〉) component is stronger than brass ({1 1 0}〈1 1 2〉) and Goss ({1 1 0}〈0 0 1〉), and strengthened with increasing annealing temperatures. Strong α-fiber (〈1 1 0〉//ND) components other than the deformation components B S and G, and higher fraction of random components also develop. It could be attributed to profuse annealing twin formation due to the low stacking fault energy of the alloy.

Effects of Rolling Parameters on Texture and Formability of High Strength Ultra-Low Carbon BH Steel

The effects of hot rolling and cold rolling parameters on texture and r (plastic strain ratio) value of high strength ultra low carbon bake hardening (ULC-BH) steels are studied with orientation distribution function (ODF) structural analysis method. After hot rolling, the high strength ULC-BH steel sheet has weak γ-fiber with uniform orientation distributions, and weak γ-fiber, of which {445}>110< component forms a high intensity peak at coiling temperature of 750 °C. After cold rolling, both {111}>110<−{111}>112< intensity on the γ-fiber and {111}−{112} >110< intensity on the α-fiber enhanced. As a result of substitutional solute elements Mn and P being added to the steel, strong {112}>110< deformation texture component is observed on γ-fiber, especially at 80% cold rolling reduction, and this leads to the strong {111}>112< recrystallization texture after annealing. The increase of cold rolling reduction shifts the maximum intensity on the γ-fiber from {111}>112< to {111}>113<. After annealing, a very strong γ-fiber is obtained, with intensity peak at {111}>112< component when cold rolling reduction reaches 80%. Increasing coiling temperature and cold rolling reduction improve γ-fiber intensity and r value, resulting in good deep drawability.

Analysis of Deformation Texture in AISI 304 Steel Sheets

The textures of cold-rolled AISI 304 austenitic steel were the object of the investigations. The austenite steel was deformed by cold-rolling to 20, 40 and 70% reduction. A significant amount of martensite, formed due to the strain induced (γ®a’) transformation, was detected in the deformed structure by applying magnetic and X-ray diffraction methods. Texture analysis was performed on the basis of the orientation distribution functions (ODFs) calculated from the experimental pole figures. The texture measurements of both phases were conducted from the center layers of the cold-rolled strip. In the case of metastable austenite AISI 304 steel the texture development was very complex because three processes were proceded simultaneously during the cold-rolling, namely: plastic deformation of the austenitic g-phase, strain induced phase transformation γ®a’ and deformation of the formed a’-martensite. These processes resulted in the presence of two phases in the structure of the steel with a definite crystallographic relationship and orientation changes of both phases with increasing of the deformation. Thus, the resultant deformation texture of the investigated steels is described by the austenite and martensite texture components. The rolling texture of γ-phase describes mainly orientations from the fiber α =&lt;110&gt;║ND and the major components of the martensite deformation texture are orientations from the fibers α1=&lt;110&gt;║RD and γ ={111}║ND.

Effect of Austenite Recrystallization on Toughness of Pipeline Steels

The factors affecting pipeline fractures are reviewed briefly, with particular emphasis on the influence of the {100} texture component. The deformation texture components introduced by rolling in the austenite temperature range are introduced, together with the component changes associated with recrystallization. The effect of the γ-to-α phase transformation on the austenite deformation and recrystallization texture components is described. The changes to the texture brought about by rolling in the ferrite (or in the intercritical) phase field are also outlined. The controlled rolling parameters that promote minimization of the texture intensity of the deleterious {100} component are summarized.

Effect of crystallographic texture on the anisotropy of Charpy impact behavior in pipeline steel

The current study systematically investigated the anisotropy of fracture behavior in commercial API X100 pipeline steel. The experimental results showed that the temperature for transition from ductile to brittle fracture was significantly different in samples with different orientations, defined as anisotropy of fracture behavior in this paper. The inhomogeneity distribution of microstructure (grain size) and the crystallographic texture were systematically analyzed. The difference in grain size of the samples with different orientations can be reasonably ignored in this study. Therefore, the anisotropy of fracture behavior is attributed to the crystallographic textures in which the deformation and transformation texture components were included. The effect of crystallographic texture on the anisotropy of ductile to brittle fracture transition temperature was theoretically interpreted based on the relationship among yield strength, fracture strength, and their average orientation factor.

Transformation and Deformation Texture Study in Friction Stir Processed API X80 Pipeline Steel

The nature of deformation in friction stir welding/processing (FSW/P) is complex which is further complicated when allotropic phase transformations are present. Electron backscattered diffraction (EBSD) is used as a means to reconstruct prior austenite texture and grain structure to study deformation and recrystallization in austenite and ferrite in FSW/P of high strength low alloy (HSLA) steels. Analyses show evidence of shear deformation textures such as A1* (111)[−1−12], B (1−12)[110], and −B (−11−2)[−1−10], as well as rotated-cube recrystallization texture in the reconstructed prior austenite. Existence of rotated-cube texture as well as polygonal grain structure of the prior austenite implies that recrystallization is partially occurring in elevated temperatures. Room temperature ferrite exhibits well-defined shear deformation texture components. The observed shear deformation texture in the room temperature microstructure implies that FSW/P imposes deformation during the phase transformation. The evolution of both elevated and room temperature textures in friction stir processed API X80 steel are presented.

Microstructure and texture evolution during accumulative roll bonding of aluminium alloys AA2219/AA5086 composite laminates

Accumulative roll bonding of two aluminium alloys, AA2219 and AA5086 was carried out up to 8 passes. During the course of ARB, the deformation inhomogeneity between the two alloy layers results in interfacial instability after the 4th pass, necking of the AA5086 layers after the 6th pass and fracture along the necked regions after the 7th and 8th pass. The EBSD analysis shows deformation bands along the interfaces after 8 passes of ARB. The ARB-processed materials predominantly show characteristic deformation texture components. The weak texture after the 2nd pass results from the combination of a weakly-textured starting AA2219 layer and a strongly-textured starting AA5086 layer. A strong deformation texture forms due to the high imposed strain after a higher number of ARB passes. Subgrain formation and related shear banding induces copper/S components in the case of the small elongated grains, while planar slip leads to the formation of brass component in the large elongated grains.

Development of microstructure and texture in Copper during warm accumulative roll bonding

The evolution of microstructure and texture gradient in warm Accumulative Roll Bonded Cu–Cu multilayer has been studied. Grain size distribution is multimodal and exhibits variation from middle to surface layer. Evolution of texture is largely influenced by shear, in addition to rolling deformation. This leads to the formation of a texture comprising of high fraction of Brass and rolling direction-rotated cube components. Partial recrystallization was observed. Deformed and recrystallized grains were separated using a partition scheme based on grain orientation spread and textures were analyzed for both the partition. Retention of deformation texture components in recrystallized grains suggests the mechanism of recrystallization as continuous recrystallization. Shear deformation plays an important role in grain refinement through continuous recrystallization.

Modelling Textures Formed during the Plane Strain Compression and Subsequent Static Recrystallisation of Body-Centred Cubic (BCC) Metals

The Plane Strain Compression and Static Recrystallisation Textures of BCC Metals Have Been Simulated Using a Coupled 3D Crystal Plasticity Finite Element (CPFE)-Single Phase Field (PF) Model Using an Interstitial-Free (IF) Steel as an Example. the Recrystallisation Nucleation Is Modelled Based on the Orientation Dependent Recovery (ODR) Theory which Assumes that Deformation Texture Components with a Relatively High Number of Slip Systems Activated during the Plane Strain Compression Undergo a Faster Recovery Process during the Subsequent Annealing due to the Cross Slip of Dislocations and as a Result Will Nucleate Earlier than Others. the Growth of Strain-Free Grains Is Simulated Using the Mis-Orientation Angle Dependent Grain Boundary Energy and Interface Mobility. A Linear Interpolation Method Is Adopted to Map the Data between the CPFE Model of Deformation and the Single PF Model of Recrystallisation. Simulated Results Show a Qualitative Agreement with the Typical Rolling and Annealing Textures Measured Experimentally for BCC Metals. Apart from the Texture and Grain Structure Formed during Deformation and Annealing, the Softening Fraction Can Also Be Simulated Using the Developed Model.