Primary Recrystallization Texture Research Articles

Primary Recrystallization Texture in FCC-Metal with Low Packing Defect Energy

The method of orientation microscopy (EBSD) is used to study the special features of recrystallization texture in drawn copper wire. It is shown that the strict crystallographic relationships between deformation and recrystallization orientations are consequences of the dominant role in structural transformations of special misorientations, i.e. special boundaries. Mechanisms of the appearance and “growth” of annealing twins are proposed.

Formation of the primary recrystallization texture in the oriented electrical steel with 3% Si

The microstructure and texture of the cold rolled oriented electrical steel with 3% Si after annealing at various temperatures were characterized by means of electron backscattering diffraction (EBSD), scanning electron microscope (SEM) and X-ray diffractmeter (XRD). It was found that the preferential nucleation sites are shear bands and the deformed grain boundaries at the early stage of the recrystallization. But the nuclei at the shear bands became to the dominated recrystallized grains with annealing. According to the experimental data and calculation results using misorientation principle, the misorientation between recrystallized grains and the surrounded deformed matrix was mainly distributed in the range between 25 and 45°. High stored energy of the deformed γ-fiber components results in preferred recrystallization at the beginning of recrystallization. The recrystallized grains oriented with {111}<110> and {111}<112> maintain prominent from beginning to the end of the recrystallization. The proportion of sporadical Goss recrystallized grains is low after completion of the recrystallization. But the misorientation between Goss grains and the surrounded grains is based on the high angles ranging from 25 to 45°.

Segregation affecting the evolution of primary recrystallization textures in a ternary Fe-Si-Sn alloy

The effect of Sn addition on the primary recrystallization of cold rolled Fe-3 wt. % Si alloys is investigated. Texture evolution and misorientation distributions are analyzed on partially recrystallized samples using the electron backscatter diffraction technique (EBSD). Sn was found to affect the microstructure, throughout the thermal treatment of the materials, by refining the grains and altering the texture. In the presence of Sn, the intensity of {111}<uvw> grains is reduced through all stages of recrystallization, while that of {100}<uvw> and {hkl}<100> grains is increased. The favored growth of these latter grains is most likely due to a combination of mechanisms that involve nucleation site preferences and probably the presence of high mobility CSL boundaries. Σ5 boundaries were observed to increase in frequency with Sn through all stages of recrystallization. Additionally {100} grains were found to be most frequently correlated with Σ5 interfaces, which might be due to geometrical considerations. Site-specific characterization of grain boundaries was conducted with three-dimensional atom probe tomography (3D-APT) to measure the grain boundary segregation of Sn.

Effect of Asymmetric Hot Rolling on the Texture Evolution of Fe–3%Si Steel

In Fe–3%Si steel, the hot rolling process affects not only the hot rolling texture but also the primary recrystallization texture. Here, the effect of asymmetric hot rolling was studied by comparing the difference in the texture evolved between asymmetric and symmetric hot rolling. The effect of asymmetric hot rolling on the texture of primary recrystallized Fe–3%Si steel was also studied. The symmetric hot rolling of Fe–3%Si steel produces a rotated cube texture at the center but Goss and copper textures near the surface. Asymmetric hot rolling tends to produce Goss and copper textures even at the center like the texture near the surface. After primary recrystallization, the dominant texture at the center changes from {001} to {111} and the new texture has a higher fraction of the grains which make the low energy boundary with Goss grains than that of symmetric hot rolling.

Effects of rolling conditions on recrystallization microstructure and texture in magnetostrictive Fe-Ga-Al rolled sheets

The effects of different rolling conditions on the microstructure and texture of primary and secondary recrystallization in magnetostrictive Fe82Ga9Al9+0.1at%NbC alloy sheets were investigated. After the primary recrystallization annealing at 850 °C for 5 min, the as-rolled sheets prepared by warm-cold rolling with an intermediate annealing, can be fully recrystallized, and obtain the homogeneous matrix in which the fine dispersed NbC precipitate particles are distributed. The primary recrystallization textures of sheets with different rolling conditions consist mostly of strong {1 0 0} textures, γ-fiber textures, {4 1 1}〈1 4 8〉 texture and weak Goss texture. In the primary recrystallized sheets prepared by warm-cold rolling with an intermediate annealing, the high energy grain boundaries and ∑9 boundaries have the highest proportion. After high temperature annealing, the secondary recrystallizations of Goss grains in these sheets are more complete, and the size of abnormal grown Goss grain is up to several centimeters, which results in the strongest Goss texture. Correspondingly, the largest magnetostriction of 183 ppm is observed. The sample prepared by warm-cold rolling with an intermediate annealing, has homogeneous primary matrix, special texture components and grain boundary distribution, all of which provide a better surrounding for the abnormal growth of Goss grains. This work indicates that the control of rolling conditions of Fe-Ga-Al alloy sheets is necessary to achieve the strong Goss texture and obtain a possible high magnetostriction if other appropriate conditions (stress, domain structure) are achieved.

Cube texture evolution and magnetic properties of 6.5 wt% Si electrical steel fabricated by surface energy and three-stage rolling method

0.1 mm-thick 6.5 wt% Si electrical steel sheets with strong cube texture were successfully produced by surface energy effect and three-stage rolling method. The texture evolution and magnetic properties during the processing were briefly investigated, special attention was paid on the development of cube texture. The study shows that cube texture component was originated from the deformed cube grains existed in center layer of hot rolled sheet. During three-stage rolling and intermediate annealing, the cube texture component was enhanced. Attributed to the frequencies as well as size advantages of cube recrystallized grains during nucleation, a homogeneous microstructure associated with cube texture was produced after primary recrystallization. The mechanism responsible for the microstructure and texture of primary recrystallization was explained by strain induced boundary migration. After high temperature annealing for a long time, complete secondary recrystallization microstructure consisting of entirely large cube grains was produced by means of the surface energy effect. Both the strong cube texture and proper grain size enable final annealed sheets have excellent magnetic properties. The present study provides a new efficient way to optimize the recrystallization texture and improve the magnetic properties of double grain-oriented 6.5 wt% Si electrical steel.

Образование текстуры при прокатке и первичной рекристаллизации в сплаве Fe86Ga14

Fe-Ga alloys possess the increased magnetostriction in comparison with the traditional magnetostrictive materials Fe-Co and Fe-Al and have a number of advantages before magnetostrictive materials based of rare earths. In literature, much attention is paid to structure of Fe81Ga19, as this alloy possesses the greatest magnetostriction in one-phase area. Important condition for achievement of the best functional properties in this material is creation of certain crystallographic texture. However, the substantial difficulty at manufacture of samples and products consists in a high brittleness of alloy at such content of gallium, for this reason the features of formation of crystallographic texture at deformation and recrystallization in this alloy are studied poorly. In this work, the attempt to study influence of various modes of rolling and annealing on structure and magnetic properties of Fe-Ga alloy with the smaller content of Ga is made. The structure and texture of primary recrystallization was studied by means of an electron back-scattering diffraction. Besides field dependences of magnetization were measured, and the amount of grains with the direction of easy magnetization in different samples was estimated by the value of magnetic induction at a defined value of magnetic field on a magnetization curve. The values of magnetostriction increased with increase of volume fraction of the components including the direction of easy magnetization of iron-gallium alloy. Absolute values of magnetostriction did not exceed 50 ppm that is at the level of values for traditional materials, but does not correspond to advantages in magnetostrictive behavior of iron-gallium alloys. Plastic deformation by hot and, especially cold rolling causes great difficulties in connection with a high brittleness of alloy even with the lower value of gallium concentration. Therefore, it is necessary to find new methods of a plastic deformation of alloy or to add the chemical elements improving plastic properties of material.

Characterizing microstructure and texture after recrystallization annealing of Hi-B steel with simutaneous decarburization and nitriding

How to manufacture the high magnetic induction grain-oriented silicon steel (Hi-B steel) by the process featured with the primary recrystallization annealing was demonstrated, during which nitriding and decarburizing were simultaneously realized in laboratory. By the techniques of optical microscope, scanning electronic microscope and electron backscattered diffraction, both the microstructure and the texture in the samples were characterized. The samples had been subjected to nitriding to different nitrogen contents at two specified temperatures using the two defined microstructural parameters : the grain size inhomogeneity factor σ* and the texture factor AR. The former is the ratio of the mean value to standard deviation of grain sizes; the latter is the ratio of the total volume fraction of the harmful textures to that of beneficial textures including {110} <001>. When the N content increased from 0. 0055 % to 0. 0330% after the annealing at both 835 and 875 °C, the resultant recrystallized grain size decreased hut σ* changed little; whilst the rise of annealing temperature from 835 to 875 °C resulted in the increase in both grain size and σ*. Moreover, either the injected N content or temperature had insignificant influence on the components of primary recrystallization texture developed during annealing. However, the increase of temperature led to the decreases in both intensity and volume fraction of {001} <120> and {110} <001> textures but increases in the {114} <481> and γ fiber textures and the resultant decrease of AR.

Effect of primary recrystallization microstructure on abnormal growth of Goss grains in a twin-roll cast grain-oriented electrical steel

Various primary recrystallization microstructures and textures were produced in a twin-roll cast grain-oriented electrical steel by employing different routes. The relationship between the primary recrystallization microstructure and texture and the abnormal growth of secondary Goss grains was investigated. The results show that the cold rolling reductions have a significant influence on secondary recrystallization by changing the primary recrystallization microstructure. Sheet processed by single-stage cold rolling with 88.3% reduction displayed the poorest secondary recrystallization microstructure as it contained many small equiaxed grains. By contrast, the employment of two-stage cold rolling markedly improved the secondary recrystallization microstructure. In the case of two moderate reductions of 65.2% and 66.3%, dense deformation substructures formed during both the first and second cold rolling, leading to a homogeneous primary recrystallization microstructure together with a strong γ-fiber texture. In this way, a suitable secondary recrystallization microstructure consisting of large Goss grains was produced. In the case of the inappropriate reductions, many large λ- and α-grains in the primary recrystallization matrix blocked the growth of secondary Goss grains along the transverse direction, resulting in a poor secondary recrystallization microstructure.

Effect of slab reheating temperature on recrystallization microstructure, texture and magnetic properties of Nb-containing grain-oriented silicon steel

In this study, a Nb-containing grain-oriented silicon steel was chosen to investigate the effect of different slab reheating temperatures on the microstructure and texture of primary recrystallization and secondary recrystallization by optical microscope (OM), field emission scanning electron microscope (FE-SEM) equipped with electron backscatter diffraction (EBSD) system and transmission electron microscope (TEM). The magnetic properties of finished product were also measured. The results show that Nb(C,N) can be formed and worked as the main inhibitor after adding Nb into the traditional grain-oriented silicon steel to lower the reheating temperature of the slab. At different low slab reheating temperatures, primary recrystallization takes place in all decarburized specimens, and at 1220°C, the microstructure is the most fine and uniform. The types of primary recrystallization texture are consistent composed of strong {411}〈148〉 texture, dominated γ-fiber texture {111}〈112〉 and {111}〈110〉, weak α-fiber texture and some Goss components. The proportions of HEGB and Σ9 boundary are the highest at 1220°C after decarburization annealing, which is beneficial to the grain growth of primary recrystallization. After high temperature annealing, the specimen of 1220°C slab reheating temperature can be fully recrystallized to obtain secondary recrystallization grains on the centimeter scale, and the texture component is characterized by a single Goss texture. The magnetic properties of finished product are the best, and B800=1.88T, P1.7/50=1.31W/kg.

Correlation between Primary and Secondary Recrystallization Texture Components in Low-temperature Reheated Grain-oriented Silicon Steel

Low-temperature slab-reheated grain-oriented silicon steel is characterized by a sharp {411}<148> primary recrystallization texture. To date, the influence of this texture on secondary recrystallization is not clear. Micro-textures in primary and secondary recrystallizcd sheets of low-temperature reheated grain-oriented silicon steel were examined using electron backscatter diffraction. By comparing the textures and microstructures of specific primary recrystallized grains neighboring secondary grains with those of other primary grains, the influences of primary recrystallization textures and microstructures on the orientations of secondary grains were investigated. Results show that for low-temperature reheated grain-oriented silicon steel, the primary recrystallization sheet comprises {411}<148>, {111}<112>, and {001}<120> texture components. During secondary recrystallization, the {111}<112> primary recrystallized grains were easily consumed by abnormally grown Goss, deviated Goss, Brass, or {210}<001> grains; the {411}<148> primary recrystallized grains were more resistant to being swallowed; and the {001}<120> grains were the most resistant to being consumed. For a particular primary grain, the distribution of its surrounding grain boundaries determined how easily it is consumed during secondary recrystallization. Primary grains surrounded by 20°–15° grain boundaries were consumed much earlier than those having grain boundaries above 15°, which is in accordance with high-energy grain boundary theory. In addition, special ∑9 boundaries between {111}<148> and Goss grains move more slowly than ∑9 boundaries between {111}<112> and Goss grains, which is attributed to the different positions of <110> rotation axis with respect to the normals of grain boundaries.

Effect of Nitrogen Content on Primary Recrystallization Behavior and Magnetic Property of Hi-B Steel

The effect of nitrogen content on primary recrystallization microstructure, texture and magnetic property of Hi-B steel was studied by means of optical microscopy (OM), scanning electron microscopy (SEM), and electron backscatter diffraction (EBSD). When nitrogen content increased gradually from 0.0055% to 0.0310%, the primary grain size and variation coefficient of nitrided sheet reduced from 26.85 μm, 0.590 to 18.87 μm, 0.525 – 0.565, respectively. Meanwhile, the primary recrystallization texture style of nitrided sheet was nearly identical to the texture style of decarburized sheet before nitriding treatment, but exhibiting a certain change on texture intensity. The variation of average magnetic induction value (B8) and core loss value (P17/50) were manifested to be M-shaped and W-shaped curves, respectively. When nitrogen content reached 0.0160%, the best value of the average magnetic property of the final product was obtained as follows: the B8 and P17/50 were 1.921 T and 0.968 W/kg, respectively. Meanwhile, the best performance, B8 and P17/50, of single sheet was 1.961 T and 0.854 W/kg.

Evolution of microstructure and texture during thermo-mechanical processing of a two phase Al0.5CoCrFeMnNi high entropy alloy

The evolution of microstructure and texture during thermo-mechanical processing of two phase (FCC+BCC) Al0.5CoCrFeMnNi was investigated. For this purpose, the fully recrystallized starting material having 17% of the BCC phase was warm-rolled to 75% reduction in thickness and annealed at temperatures ranging from 1000°C to 1250°C. The volume fractions of the two phases remained unaltered during warm-rolling. Development of a lamellar deformation structure was observed for the FCC phase which also showed presence of typical deformation components. In contrast, the BCC phase showed mechanical fragmentation indicating limited ductility and a deformation texture characterized by RD (//〈110〉) and ND (//〈111〉) fibers. Development of a finer recrystallized microstructure was observed after annealing at 1000°C due to the grain boundary pinning exerted by the BCC phase, thus inhibiting grain growth. The BCC phase fraction decreased consistently with increasing annealing temperature. Considerable grain growth happened after annealing at 1250°C due to the decrease in the BCC fraction, which greatly diminished the grain boundary pinning. The BCC phase also showed stronger ND-fiber in the primary recrystallization texture, which weakened with increasing annealing temperature due to the dissolution of this phase. Retention of the deformation texture components in the recrystallization texture of the FCC phase indicated absence of strong preferential nucleation or growth.

Secondary recrystallization and magnetostriction in binary Fe81Ga19 thin sheets

Strong Goss texture ({110}〈001〉) was successfully developed by secondary recrystallization in Fe81Ga19 sheets without conventional application of inhibitor or surface energy effect as grain-oriented silicon steel. Goss grains cover 90% surface area of annealed sheet, and the magnetostriction coefficient reaches up to 262 ppm. The primary recrystallization microstructure and texture provide the prerequisites for nucleation and abnormal grain growth of secondary Goss grains. The dispersedly distributed Goss grains do not exhibit an evident advantage in grain size and number, and the normal grain growth of matrix grains can be inhibited by low-angle grain boundaries before onset of secondary recrystallization. The existence of low-angle grain boundaries is proposed to be an important factor for the occurrence of secondary recrystallization in binary Fe-Ga sheets based on grain boundary character distribution analysis.

Variations in through-thickness recrystallization and grain growth textures in the Al layers in ARB-processed Al/Al(0.3% Sc) composite sheets

This investigation aims to understand the differences in the recrystallization and grain growth textures in aluminum layers along the thickness direction of two layered composite sheets. The sheets were processed by five cycle accumulative roll bonding of commercially pure aluminum and an aluminum alloy containing 0.3wt.% Sc both in the supersaturated solid solution and artificially aged conditions. Electron back scattered diffraction and transmission electron microscopy were used to characterize the microstructure and crystallography of the rolled and annealed composites. During the early stages of annealing the β-fiber rolling textures remain unchanged and becomes sustained by the so-called continuous recrystallization process. Then, at the completion of primary recrystallization in the later stages of annealing, orientation selective recrystallization occurs and the Brass orientation becomes eliminated. A strong β-fiber primary recrystallization texture was found to be favorable for the secondary recrystallization growth of Cube orientations. Otherwise, conventional grain growth occurs when the primary recrystallization textures have distortions in the β-fiber.

Microstructure and Texture Evolution of Strip Casting Grain-Oriented Silicon Steel

A 0.23 mm thick grain-oriented silicon steel sheet was successfully produced based on strip casting and two-stage cold rolling route. The evolutions of microstructure and texture along the complete processing route were briefly investigated. It was shown that the as-cast strip was composed of coarse ferrite grains and martensite, and the texture was mainly characterized by strong {001} $\langle 0vw\rangle $ texture. Goss texture was absent in the hot-rolled strip, which was distinct from the well accepted results that Goss texture had its origin during hot rolling. After the cycle of the first-stage cold rolling, an intermediate annealing, the second-stage cold rolling, and a primary annealing, the strip exhibited a fully recrystallized microstructure with a weak $\alpha $ -fiber texture and a relatively strong $\gamma $ -fiber texture. Goss texture was not observed through the thickness of the primary annealed strip. This was significantly different from the previous results that Goss texture was the most populous component in the primary recrystallization texture of two-stage route in conventional process. After secondary recrystalization annealing, the magnetic induction $B_{8}$ of the sheet was as high as 1.84 T.

Development of microstructure and texture in strip casting grain oriented silicon steel

Abstract Grain oriented silicon steel was produced by strip casting and two-stage cold rolling processes. The development of microstructure and texture was investigated by using optical microscopy, X-ray diffraction and electron backscattered diffraction. It is shown that the microstructure and texture evolutions of strip casting grain oriented silicon steel are significantly distinct from those in the conventional processing route. The as-cast strip is composed of coarse solidification grains and characterized by pronounced 〈001〉//ND texture together with very weak Goss texture. The initial coarse microstructure enhances {111} shear bands formation during the first cold rolling and then leads to the homogeneously distributed Goss grains through the thickness of intermediate annealed sheet. After the secondary cold rolling and primary annealing, strong γ fiber texture with a peak at {111}〈112〉 dominates the primary recrystallization texture, which is beneficial to the abnormal growth of Goss grain during the subsequent high temperature annealing. Therefore, the secondary recrystallization of Goss orientation evolves completely after the high temperature annealing and the grain oriented silicon steel with a good magnetic properties ( B 8 =1.94 T, P 1.7/50 =1.3 W/kg) can be prepared.

Fabrication of grain-oriented silicon steel by a novel way: Strip casting process

A 0.23mm-thick grain-oriented silicon steel sheet was successfully produced by a new process including strip casting, hot rolling, normalizing, two-stage cold rolling with an intermediate annealing, primary annealing and secondary recrystallization annealing. Microstructure, texture and inhibitor evolutions were briefly investigated. It was shown that Goss texture was absent in the hot rolled strip. After normalizing, a number of finely dispersed MnS precipitates with a diameter of 20–80nm were formed. The primary annealed strip exhibited fully recrystallized microstructure with the average grain size of 13μm, together with weak α-fiber and relatively strong and uniform γ-fiber texture. However, the Goss texture was not observed, which was significantly different from previous results that the Goss texture was the most populous component in the primary recrystallization texture of two-stage route. After secondary recrystallization annealing, very large grains with a grain size of 6–40mm were formed and the magnetic induction B8 was as high as 1.84T.

Effects of ColdRolling Process on Primary Recrystallization Texture of Grain Oriented Silicon Steel

Effects of ColdRolling Process on Primary Recrystallization Texture of Grain Oriented Silicon Steel

Effects of Post-Rolling Anneal on the Primary Recrystallization Structure and Texture of High Permeability Grain-Oriented Silicon Steel

The decarbonized strips of high permeability grain-oriented silicon steel were annealed at different temperatures in a furnace after rolling at the ratio of 21.1%. The changes of the structure and the texture were analyzed by optic microscope and X-ray diffraction. Results show that the grains are easy to grow up and coarse after annealing, while the texture of the strips changes gradually from {111}&lt;112&gt; to {118}&lt;110&gt; and rotary cubic texture as the annealed temperature rises. The mechanism is that at a relatively lower cold rolling ratio, the distortion storage energy of the ferrite grains in the directions of {118}&lt;110&gt; and {100}&lt;110&gt; is higher than that of the {111}&lt;112&gt; grains so that the texture can form after a suitable annealing process.