Final Recrystallization Texture Research Articles

Evolution of Recrystallization Texture in A286 Iron-Based Superalloy Thin Plates Rolled via Various Routes

The A286 iron-based superalloy has wide-ranging applications in replacing expensive nickel-based and cobalt-based superalloy to manufacture the turbine disk as well as the pipelines and valves of the fourth-generation supercritical water reactor (SCWR) working below 650 °C. The recrystallization texture importantly affects the mechanical properties and oxidation resistance of superalloys. However, very few investigations are available on the recrystallisation texture of A286 alloy. The current work reports the texture of A286 alloy fabrication using various rolling routes, including one-stage cold rolling with the rolling rates of 83% (Route I) and 91% (Route II), and two-stage cold rolling with the rolling rate of 83% + 50% (Route III). Route III is preferentially recommended to manufacture A286 alloy thin plates due to the obviously reduced work hardening as well as the weakened recrystallization texture and anisotropy; moreover, compared with other routes, the recrystallized grain size of Route III did not significantly coarsen. We also revealed the mechanism for the effect of cold rolling textures on the final recrystallization texture and the role of the deformation twin in {110} <115> grain. In this study, recrystallization texture develops through two independent mechanisms related to different deformation microstructures, including the recrystallization texture inherited from deformation texture and the recrystallization texture depended on deformation twins.

Comparative study on microstructure and texture evolution of low silicon non-oriented electrical steels along one-stage and two-stage cold rolling processes

Fe-0.9% Si-0.3% Al non-oriented electrical steels were fabricated by two-stage cold rolling process including hot rolling, first cold rolling, intermediate batch annealing, second cold rolling and final annealing, in which the first cold rolling reduction varied from 15% to 54%. One-stage cold rolling process with hot band normalization was also investigated for comparison. The findings revealed that, in two-stage cold rolling process, the final recrystallization texture and magnetic properties heavily relied on the rolling reduction schedule. As the first rolling reduction increased, the core loss increased and the magnetic induction decreased owing to the enhanced γ-fiber (〈111〉//ND) texture in the final annealed sheets. Relatively lower first cold rolling reduction (15%) was beneficial to generate coarse grains during intermediate annealing and led to large grains with weakened γ-fiber and enhanced Goss textures in final sheets. By contrast, relatively higher first cold rolling reduction (30% and 54%) caused small grains by promoting the occurrence of recrystallization during intermediate annealing and resulted in small grains with stronger γ-fiber texture after final annealing. The hot band normalization in one-stage cold rolling process could also effectively improve the grain size prior to cold rolling, though MnS precipitate and sharp γ-fiber recrystallization texture were promoted in the final sheets due to the high normalization temperature and much higher cold rolling reduction, respectively. Therefore, two-stage cold rolling process was propitious to reduce γ-fiber recrystallization texture and MnS precipitate compared with one-stage cold rolling process. The appropriate rolling reduction schedule (15%+75.6%) and suitable intermediate annealing process (750 °C for 1.5 h) were propitious to produce high-performance non-oriented silicon steel with lowest core loss and highest magnetic induction.

Enhanced grain refinement and texture weakening in Al–Mg–Si alloy through a novel thermomechanical processing

A novel thermomechanical processing including solution treatment, first rolling with large deformation and overaging based on particle-stimulated nucleation of recrystallization (PSN) was proposed to obtain an Al–Mg–Si alloy sheet with fine grain structure, weak texture and high plastic strain ratio. The difference between conventional thermomechanical processing and novel thermomechanical processing with two overaging time parameters was investigated by texture and microstructure characterization and tensile tests. The results show that the finest grain structure with an average size of 17 µm, the weakest recrystallization texture with a volume fraction of 8.4 %, the highest average plastic strain ratio r of 0.69 and the lowest planar anisotropy Δr of − 0.001 were acquired by the novel thermomechanical processing with a long overaging time. In comparison with conventional thermomechanical processing, the novel thermomechanical processing can generate completely different particle distributions and tends to develop a weak texture consisting of the CubeND {001}<310>orientation. Increasing the overaging time is effective in coarsening the particles and thus refining the grain structure, weakening the texture, and improving the average r and Δr values. The genetic characteristics of texture evolution and the particle distribution determine the final recrystallization texture.

On the influence of deformation mechanism during cold and warm rolling on annealing behavior of a 304 stainless steel

In the present study, a 304 stainless steel was deformed at different temperatures of room temperature (cold rolling) and 200 °C (warm rolling) for elucidating the distinct deformation mechanisms, and then, the influence of the deformed microstructures on the subsequent microstructural evolution and texture development during annealing treatments was studied. The results indicated that deformation-induced martensite transformation was the dominant deformation mechanism during cold rolling, and a mixed microstructure consisting of ~60% volume fraction of α'-martensite and deformed austenite was obtained. Deformation twinning of austenite dominated the deformation during warm rolling. The underlying reason was the increasing SFE with deformation temperature, which inhibited the martensitic transformation but promoted the formation of deformation twins. On annealing, the recrystallization of retained austenite in cold-rolled samples was retarded because of martensitic reversion compared to the warm-rolled samples. Completely recrystallized structure with average grain size of ~0.7 µm was obtained in both cold and warm-rolled samples after annealing at 800 °C. Texture evolution indicated that martensitic reversion enhanced the intensity of {110}< 112 > texture in cold-rolled and annealed samples. However, the final recrystallization texture components were consisted of {110}< 112 > and {113}< 211 > regardless of rolling process. Furthermore, structure-property relationship was established, and combination of high strength and excellent plasticity can be obtained in both cold and warm-rolled sheets by tuning the subsequent annealing parameters.

Texture evolution behavior and anisotropy of 2A97 Al–Li alloy during recrystallization at elevated temperature

2A97 Al–Li alloy was cold-rolled to 2 mm and then thermally exposed at different temperatures for 1 h and at 723 K for different time, respectively. The texture evolution behavior and the anisotropy of 2A97 Al–Li alloy were investigated. The result shows that the {001} 〈120〉 and {011} 〈233〉 textures are the dominant recrystallization texture. The {124} 〈211〉 texture is the final recrystallization texture. In case of low-temperature thermal exposure (473, 573 K), the {011} 〈211〉 texture is aggregated to the {112} 〈111〉 and {123} 〈634〉 textures. During the recrystallization at 723 K, the {001} 〈110〉, {111} 〈112〉 and {011} 〈100〉 textures are the intermediate transition grain orientations. The concurrent precipitation of Al20Cu2Mn3 and Al3Zr results in the occurrence of unusually sharp {011} 〈233〉 and {001} 〈120〉 texture components during recrystallization. The alloy with both recrystallization and deformation texture possesses the smallest anisotropic, and the texture is the direct reason that results in the anisotropy.

Effect of Zn on microstructure, texture and mechanical properties of Al-Mg-Si-Cu alloys with a medium number of Fe-rich phase particles

The effect of Zn on the microstructure, texture evolution and mechanical properties of Al-Mg-Si-Cu alloys with a medium number of Fe-rich phase particles was investigated using tensile testing machine, optical microscopy (OM), scanning electron microscope (SEM), transmission electron microscope (TEM) and X-ray diffractometer (XRD) in the present study. The results show that Zn addition has a significant influence on the final mechanical properties, but a slight effect on microstructure and final recrystallization texture. Zn addition is favorable to increase yield strength, ultimate tensile strength and elongation, however it is detrimental to improve r value and reduce Δr value. During the thermomechanical processing, the microstructure almost has nothing to do with Zn addition. However, Zn could prevent the secondary phase particles from precipitating during intermediate annealing. In contrast to the alloy sheet without Zn, the alloy sheet with 1.0wt% Zn always has weaker textures before final cold rolling, but a stronger texture after experiencing final cold rolling. After solution treatment, they almost possess the same recrystallization texture. Finally, the effect of Zn addition on the recrystallization texture was discussed. Their similar recrystallization texture can be attributed to the similar microstructure, which was caused by the medium number of Fe-rich phase particles.

Texture evolution during skew cold rolling and annealing of a non-oriented electrical steel containing 0.9 wt% silicon

A novel rolling technique, i.e., skew rolling, was applied to a non-oriented electrical steel containing 0.9 wt% Si, aiming at altering the texture of the final sheets that usually contain the magnetically unfavorable //ND fiber after conventional rolling and annealing. The texture after skew cold rolling was compared to those obtained from conventional rolling and cross rolling and significantly different textures were observed. The cold-rolled steel sheets were then annealed and the texture evolution was investigated using a quasi in situ electron backscatter diffraction technique, i.e., tracking the microtexture of the same area at various holding times at the same temperature. The development of the recrystallization microstructure and microtexture (nucleation and grain growth) was characterized and the effect of skew rolling on the final texture was studied. The mechanisms governing the formation of the final recrystallization texture, e.g., preferential nucleation and selective growth, were elucidated.

Effects of rolling temperature on microstructure, texture, formability and magnetic properties in strip casting Fe-6.5 wt% Si non-oriented electrical steel

Fe-6.5wt% Si non-oriented electrical steel sheets with a thickness of 0.50mm were produced by using a new processing route: strip casting followed by hot rolling, intermediate temperature (150–850°C) rolling and final annealing. The present study focused on exploring the effects of rolling temperature varying from 150 to 850°C on the microstructure and texture evolution, the formability and final magnetic properties. The microstructure and texture evolution at the various processing steps were investigated in detail by using OM, XRD, EBSD and TEM. It was found that the formability during rolling, the microstructure and texture before and after annealing and final magnetic properties highly depended on rolling temperature. The formability during rolling was gradually improved with increasing rolling temperature due to the slipping of dislocation. In particular, the rolling temperature dominated the formation of in-grain shear bands in the rolled microstructure, which played an important role in the development of final recrystallization microstructure and texture. In the case of lower temperature (150–450°C) rolling, an inhomogeneous microstructure with a large amount of in-grain shear bands was formed in the rolled sheets, which finally resulted in a fine and inhomogeneous annealing microstructure dominated by mild λ-fiber texture composed of cube and {001}〈210〉 components and α*-fiber texture concentrated on {115}〈5–10 1〉 component. By contrast, in the case of higher temperature (650–850°C) rolling, a relatively homogeneous microstructure without in-grain shear bands was formed instead in the rolled sheets, which finally led to a coarse and relatively homogeneous annealing microstructure characterized by strong α-fiber and γ-fiber texture. Accordingly, on the whole, both the magnetic induction (B8 and B50) and iron loss (P15/50 and P10/400) decreased with raising rolling temperature.

Influence of the angle between cold rolling direction and hot rolling direction on the texture evolution of non-oriented electrical steels

In processing non-oriented electrical steel sheets using conventional rolling schemes, the most common texture components obtained after final annealing are the magnetically unfavourable <111>//ND (γ) and <110>//RD (α) fibres. A lot of researches have been carried out trying to optimize the processes to produce the favourable <001>//ND (θ) fibre. However, since the final texture is formed through a series of texture evolution steps during the solidification, hot rolling, cold rolling and annealing processes, it is quite challenging to tailor the texture of the final product. In this study, a new rolling scheme was examined, in which the cold rolling direction (CRD) was inclined to the hot rolling direction (HRD) at an angle from 0° to 90° (with a 15° increment). This was intended to alter the texture commonly produced by cold rolling along the HRD, and to optimize the final recrystallization texture. The cold rolling and recrystallization textures of two non-oriented electrical steels with 0.9% and 2.8% Si were measured. It was found that the inclination of CRD to HRD has a substantial effect on the cold rolling texture for both steels, but only in the low Si steel, does it lead to significantly different recrystallization textures. A strong cube texture was produced at an inclination angle of 60°, and the <111>//ND (γ) fibre was significantly weakened or essentially disappeared. The core losses of these steels were measured by Epstein frame method and the results showed a ∼10% difference among strips cold rolled at different angles. A minimum core loss occurred at a 45° inclination angle in the low Si steel.

Effects of warm temper rolling on microstructure, texture and magnetic properties of strip-casting 6.5 wt% Si electrical steel

6.5wt% Si electrical steel thin sheets were produced by a processing route including strip casting, hot rolling, warm rolling, intermediate annealing, warm temper rolling and final annealing, in which the warm temper rolling reduction varied from 2.7% to 14.4%. A detailed study of the microstructural and textural evolutions through the whole processing route was carried out by optical microscopy, X-ray diffraction and electron backscattered diffraction analysis. The findings revealed that the final recrystallization microstructure, texture and magnetic properties relied heavily on the warm temper rolling reduction. As the warm temper rolling reduction increased from 2.7% to 14.4%, the finally recrystallized microstructures were more homogeneous and the average grain size was decreased. At the warm temper rolling reduction lower than 7.0%, the occurrence of the exaggeratedly large annealing grains which dominated the whole sheet thickness resulted in strong 〈001〉//ND fiber, parallel α-fiber, 〈111〉//ND fiber and many other strong hard-magnetization texture components. By contrast, at the warm temper rolling reduction higher than 7.0%, the recrystallization textures were characterized by weak 〈001〉//ND fiber, parallel α-fiber, 〈111〉//ND texture, together with fewer and weak hard-magnetization texture components. The mechanism responsible for the finally microstructural and textural changes was explained by strain induced boundary migration. As warm temper rolling reduction increased, the magnetic properties at high frequency were gradually improved due to smaller grain sizes and more desirable textures. The highest magnetic inductions of 1.383T (B8), 1.484T (B25) and 1.571T (B50) in combination with the lowest iron losses at high frequencies of 19.11W/Kg (W10/400) and 3.824W/Kg (W2/1000) were obtained at 14.4% warm temper rolling reduction under the applied condition.

Microstructure and texture evolution of strip casting 3 wt% Si non-oriented silicon steel with columnar structure

An Fe-3 wt%Si strip with columnar structure and pronounced {0 0 1}〈0 v w〉 texture was produced using a twin-roll strip caster. Then the as-cast strip was cold-rolled and annealed. The microstructure and texture evolution along the processing steps was investigated. It is found that inhomogeneous microstructure is produced in both cold-rolled and final annealed samples due to the large initial grains. The cold rolling texture is dominated by pronounced a-fiber texture and relatively strong γ-fiber texture. The final recrystallization texture is characterized by {0 0 1}〈0 1 0〉, {0 0 1}〈2 1 0〉, {1 1 0}〈0 0 1〉 texture and a slightly shifted {1 1 1}〈1 1 2〉 component. The microstructural inhomogeneity plays an important role in the texture evolution.

Composition and orientation effects on the final recrystallization texture of coarse-grained Nb-containing AISI 430 ferritic stainless steels

Composition and orientation effects on the final recrystallization texture of three coarse-grained Nb-containing AISI 430 ferritic stainless steels (FSSs) were investigated. Hot-bands of steels containing distinct amounts of niobium, carbon and nitrogen were annealed at 1250°C for 2h to promote grain growth. In particular, the amounts of Nb in solid solution vary from one grade to another. For purposes of comparison, the texture evolution of a hot-band sheet annealed at 1030°C for 1min (finer grain structure) was also investigated. Subsequently, the four sheets were cold rolled up to 80% reduction and then annealed at 800°C for 15min. Texture was determined using X-ray diffraction and electron backscatter diffraction (EBSD). Noticeable differences regarding the final recrystallization texture and microstructure were observed in the four investigated grades. Results suggest that distinct nucleation mechanisms take place within these large grains leading to the development of different final recrystallization textures.

Cube Textured Substrates for YBCO Coated Conductors: Influence of Initial Grain Size and Strain Conditions During Tape Rolling

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> The realization of high critical current density YBCO-based coated conductors in the RABiTS approach is primarily related to the sharpness of cube texture developed in the substrate. Among the various proposed Ni-based tapes, Ni-W alloys have attracted a particular interest either because of the enhanced mechanical properties and reduced magnetism with respect to pure Ni, or of the sharp and almost pure cube texture that can be induced. The only other remarkable component associated with cube orientation consists of its twins, whose formation is known to be primarily determined by the stacking fault energy, which is a characteristic of the material. Despite this fact, the obtained textures for a given material can significantly vary, suggesting that the deformation regime, as well as the initial bulk conditions, have a role in influencing twins formation. In this contribution, the effect of the strain conditions during mechanical deformation and initial bulk grain size on the final recrystallization texture are evaluated. EBSD and x-ray analyses evidence the influence of the initial grain size on the recrystallization texture, since sharper cube textures with reduced non-cube components develop in finer-grained starting material. Conversely the condition of plane strain deformation plays no role in determining the recrystallization texture. </para>

Orientation imaging microscopy studies of recrystallization in interstitial-free steel

The origin of the γ fiber recrystallization texture in interstitial-free (IF) steel developed during continuous annealing has been investigated by scanning electron microscopy (SEM) and orientation imaging microscopy (OIM). Nucleation of {111} «uvw» oriented crystals occurs in deformation banded γ grains and therefore a comprehensive study of microstructure of cold-rolled IF steel in the sections perpendicular to the rolling and transverse directions (TDs) and the rolling plane (RP) has been carried out to understand the formation, geometry, and microstructural features of recrystallization. The RP section gave abundant evidence of orientation gradients formed in γ oriented grains that had been subject to orientation splitting to give deformation bands. These orientation gradients across a single grain are around 5 to 30 deg and this orientation difference is sufficient to form nuclei with mobile interfaces during annealing and hence to create chains of γ oriented new grains in the original hot band γ grain envelopes. A grain impingement model requiring orientation pinning is then proposed to explain how these grains, contained in deformed γ grain envelopes, grow out into their neighbors to dominate the final recrystallization texture of IF steel. The α deformed grains contain only small lattice curvatures, and therefore in-grain nucleation is rare. These grains are mostly consumed by invading γ grains toward the end of the recrystallization process.

Effect of Through‐Thickness Macro and Micro‐Texture Gradients on Ridging of 17%Cr Ferritic Stainless Steel Sheet

In order to study the formation of ridging in ferritic stainless steel (FSS) sheets, the evolution of the crystallographic texture was investigated by macro and micro‐texture measurements throughout the thickness of the sheets. The as‐received hot band material displayed a pronounced through‐thickness texture gradient with a strong rotated cube orientation in the sheet center layer. The initial texture of the hot band had a high impact on the formation of the cold rolling texture and on the final recrystallization texture. Modification of the cold rolling texture by means of cross‐rolling led to an improvement of the macro and micro‐textures after final recrystallization annealing, which gave rise to an enhanced sheet formability in FSS. Tensile tests of specimens with half thickness revealed that ridging formed in the sheet center was much stronger than that in the surface. This observation was attributed to the more frequent formation of orientation colonies in the sheet center when compared to the sheet surface.

Producing a Random Recrystallization Texture in 6111 Aluminium Alloy

6111 Aluminium Alloy in the hot band state was cold rolled to 80% was then annealed at 450oC, 500oC and 540oC for recrystallization. The hot band was also solution heat treated, cold rolled and annealed to the same temperature to look at the difference in the recrystallization texture and precipitation states. It was found that the samples which were cold rolled and annealed without solution heat treatment gave Goss and P components after annealing. For the samples with solution heat treatment, the 450oC sample has a retained Cu type rolling texture while for the 500oC and 540oC the textures are quite random. The retained rolling texture found in the 450oC sample is due to the fact that it was partially recrystallized as the precipitates prevent complete recrystallization. The difference in the precipitation states during and after annealing of the samples with and without solution heat treatment affects the final recrystallization texture.

Monte Carlo modelling of recrystallization in metals

A Monte Carlo (MC) procedure was applied to study static recrystallization processes. The initial microstructure, stored energy and orientation within each grain were taken from EBSD measurements. Site orientations used in the model may change continuously in Euler space. Several types of site saturated nucleation were implemented in the model. A standard MC algorithm was used and tested in several ways. The grain size distribution and final recrystallization texture obtained from the model were compared with experimental ones. The agreement between both sets of data is satisfactory. As some minor experimental effects are not observed in the model, some improvements are finally proposed.

Recrystallization Mechanisms in Wire-Drawn Copper

Wire-drawn Electrolytic Tough Pitch copper deformed at moderate strain has been investigated with Electron Back Scattered Diffraction in a Scanning Electronic Microscope in order to evaluate the recrystallization mechanisms at the meso-scale. Experimentally, it has been shown that the static recrystallization takes place first in the highly deformed and misoriented areas, in the intermediate regions of the wire. The grains related to the &lt;100&gt; fiber nucleate and grow first in these regions, but some other orientations (including the &lt;111&gt; oriented grains) - that have a combined nucleation/growth potential - develop in second time. The annealing twinning is active from the beginning of the recrystallization and tends to randomize the final recrystallization texture.

Modification of the Recrystallization Texture by Means of Cross Rolling in Ferritic Stainless Steel Sheets

In order to optimize the recrystallization texture of ferritic stainless steel sheets, the crystallographic texture was modified by means of cross rolling. The as-received hot band displayed pronounced through-thickness texture gradients with a strong rotated cube orientation in the sheet center layer. After the conventional normal rolling, the strong initial texture was retained. Pronounced{001}&lt;110&gt; in the rolling textures led to the formation of {334}&lt;483&gt; in the final recrystallization texture. Cross rolling in the present work was performed by a 45° rotation of RD around ND. Cross-rolling led to a weakening of {001}&lt;110&gt; orienations. After recrystallization annealing the cross-rolled samples displayed stronger {111}//ND orientations. The orientation stability during the rolling deformation was tackled by means of Taylor deformation model.

Recrystallization kinetics and associated textures of Cu-bearing Ti-IF steels

The influence of copper on recrystallization of Ti-stabilized interstitial free steels has been studied. It is shown that the recovery and the recrystallization kinetics are slowed down. Thus the final recrystallization texture is modified: whereas the γ-fiber is still present, its intensity is lower. The deformed α-fiber contribution is larger than without copper and its magnitude depends on the annealing conditions: it is all the more intense as the heating rate is small. These effects are related to the presence of copper-based precipitates. The recrystallization textures are discussed in function of the precipitates evolution.