Goss Texture Formation Research Articles

Numerical and experimental investigation of the dynamic mechanical behavior of precipitation-strengthed NiCoCrSi0.3C0.048 medium-entropy alloy

An extended crystal plasticity model and an optimized neural network are established to investigate the mechanical behavior of CoCrNiSi0.3C0.048 Medium entropy alloy (MEA) with a three-level hierarchical precipitation structure under dynamic compressive deformation at a variety of ranges of strain rates. The interaction between the matrix and first-level precipitates is described by a presented hybrid representative volume element RVE model, involving the effects of volume fraction (Vf), radius and geometric distribution on heterogeneous deformation. Effects of second- and third-level precipitates are realized through the extended crystal plasticity constitutive model, reflecting the motion mechanism of dislocations near the precipitates in the form of initial slip resistance. Meanwhile, this study investigates the influence of the presence of primary precipitates on the initiation of slip systems within special grains with Goss or S orientations in the matrix. Additionally, it provides a more in-depth explanation of the underlying principles behind the suppression of Goss texture formation by the precipitates from the perspective of slip systems analysis. The changing of volume fractions affects flow stress evolution. Avoiding suffering from expensive computational consumption by the crystal plasticity finite element method, an artificial neural network model optimized through a genetic algorithm, is presented to predict stress-strain responses and texture evolution results under varying compression strain rates. A reliable dataset derived from crystal plasticity finite element models and experimental results is utilized to train, test, and validate the genetic algorithm-based artificial neural network model. This model demonstrates good prediction capability in dynamic mechanical behavior and texture evolution, showcasing the feasibility and efficacy of the proposed neural network model. Compared to the CPFEM method, neural network models can greatly improve computational efficiency.

A Study on the Formation of Fiber Texture in the Subsurface Layer of Hot-Rolled Plate of 3.2%Si Grain-Oriented Steel

During the hot rolling process, inhomogeneity microstructure and variations of texture along the thickness direction of hot-rolled plate were formed through shear deformation and recrystallization. The purpose of this study is to investigate the formation and evolution of fiber texture in hot-rolled plate of grain-oriented silicon steel. The results indicate that, in the surface layer s = 1 of hot-rolled plate, a large number of equiaxed grains are formed under high shear force. Under the surface layer, as shear force gradually decreases along the thickness direction, the grain aspect ratio of recrystallized grains gradually increases along the thickness direction of hot-rolled plate, and the shape of the recrystallized grains formed in the subsurface layer and center layer becomes more irregular along the thickness direction. Under the combination of compressive force and decreasing shear force along the thickness direction, fiber texture composed of dozens of specific orientations (such as {112}<111>, {110}<112>, {213}<364>, {441}<104> and Goss orientations) is formed in the subsurface layer s = 0.5~0.9 and gradually evolves along the thickness direction. Therefore, the formation of Goss texture is a small part of fiber texture and is the result of texture evolution in the subsurface layer s = 0.5~0.9.

Dislocation-assisted particle dissolution: A new hypothesis for abnormal growth of Goss grains in grain-oriented electrical steels

The physical mechanisms that lead to the abnormal growth of Goss-oriented grains in grain-oriented electrical steel (GOES) are still not well understood, despite almost a century of research. The present paper reviews the existing hypotheses on the formation of Goss-oriented grains by abnormal grain growth and provides more insights into the underlying mechanism for Goss texture formation by proposing a new hypothesis named “Dislocation-assisted particle dissolution”. Abnormally grown Goss-oriented grains in fully-processed industrial GOES samples are shown to contain a fine network of internal subgrain boundaries with very low angle (0.03° - 0.18°) each consisting of regular arrays of dislocations. These subgrain boundaries form a branched ray-like pattern from the Goss grain center towards its perimeter, i.e. they seem to have evolved with the grain during its growth. Structural and compositional analysis of these dislocations by controlled electron channelling contrast imaging (cECCI) and atom probe tomography (APT) show that these dislocations are enriched with solutes such as Sn, Cu, C, and more importantly, with Al, N and Mn, which all build the composition of the inhibitor particles that assist the abnormal growth of Goss-oriented grains. Additionally, molecular statics (MS) calculations are employed to compare the segregation tendencies of Al atoms on dislocations and on Σ9 boundaries. It is found that Al prefers to segregate to dislocations rather than to the boundaries. The origin and the role of subgrain boundaries are discussed based on the experimental and simulation results. The results indicate that, after the dissolution of inhibitors along the grain boundaries, solutes are absorbed by the subgrain dislocations. As a result, grain boundaries surrounding Goss grains become less decorated by solutes and precipitates and more mobile compared to the boundaries of matrix grains.

Texture and Magnetic Property of Fe-6.5 wt % Si Steel Strip with Cu-Rich Particles Modification.

Based on the ordered phase effectively suppressed by rapid solidification technology, the grain refinement concept using Cu is incorporated into the soft magnetic materials. Cu dosage not only could refine the grain size with an average grain size of 8.7 μm but also improve the continuity and consistency of Fe-6.5 wt % Si steel strip. It mainly attributes to the Cu-rich particles precipitating at the grain boundary, nailing the grain boundaries movement and inhibiting the grain growth, and then improving the magnetic properties and mechanical properties. The 1.5 wt % Cu sample exhibits an excellent magnetic property with the saturation magnetization of 236.54 emu/g, which mainly attributes to the strong η, λ, Goss texture formation and the band structure optimization of Si-Cu comodification. Furthermore, the mechanical properties of the steel strip are effectively improved, and the failure plastic deformation of 1.5 wt % Cu steel strip is about 11%. The rapid solidification with Cu-dosage refinement technology also has a remarkable reference on the mechanical properties and magnetic properties modification of other metal materials.

Orientation relationship of texture development in hot-rolled W during annealing

Severe through-thickness texture inhomogeneity is apt to occur during hot-rolling of tungsten. This raises the intriguing notion of how is the inhomogeneity affected by stress-involved or heat-involved factors of the thermo-mechanical process. The texture development in the bulk and at the surface were investigated, and the main focus was on the role of grain boundaries on texture development. The deformed texture at the surface and in the bulk seems similar, but the recrystallized texture of them evolves in entirely different manner, hence, the through-thickness effect is considered to be unilaterally triggered by heat-involved factor, i.e., “annealing” rather than “straining”. In the bulk, the recrystallized orientation basically retains the starting deformed γ-texture and θ-texture even if grain growth occurs. Meanwhile some subtle alternations (nucleation behaviors) show statistically a strong correlation with CSL relationships. At the surface, the deformed γ-texture is completely replaced by a prominent Goss texture ({110}〈001〉) at 1100 °C. The grain boundary plane distribution (GBPD) analysis demonstrates that the formation of Goss texture at the surface is controlled by low angle grain boundaries (LAGBs) and {112}〈111〉 or {100}〈110〉 oriented nucleation is controlled by Σ3 CSL boundary.

Unravelling the Role of Aging During Cold Rolling on the Primary Recrystallization of Grain-Oriented Electrical Steels Using a Robust EBSD-Based Analysis Approach

Aging during cold rolling improves the final magnetic properties of conventionally processed grain oriented electrical steels (GOES). In order to determine the influence of aging on the evolution of microstructure and texture during recrystallization, identical hot rolled GOES sheets, were cold rolled with and without aging, and examined by large-area electron backscatter diffraction (EBSD) investigations. Local misorientations were determined from the EBSD maps with a noise-correction technique and the statistical relevance of the EBSD-based texture measurements was examined and confirmed by a new approach. The most important effect of aging was found to be a significant modification of the deformation and recrystallization behaviour of the α-fiber components. In fact, the aging treatment resulted in more shear banding during cold rolling, which is attributed to dislocation pinning by carbon atoms. The dislocation pinning furthermore leads to significantly reduced recovery during annealing, which finally results in a higher remaining driving force for recrystallization and more nucleation sites in the otherwise sluggishly recrystallizing α-fiber grains. As a result the grain size of the aged material is significantly reduced. We assume that this smaller grain size provides a higher driving force for the subsequent growth of the Goss grains and leads to improved magnetic properties of the final processed GOES, although these relations have not been investigated here. In contrast, the α*-fiber, which is often suggested to be of importance for optimized Goss texture formation, was not found to be affected significantly by the aging treatment.

New Process for the Goss Texture Formation and Magnetic Property in Silicon Steel Sheet by Hot Asymmetric Rolling and Annealing

The shear deformation texture of bcc metals is characterized by the Goss orientation, or {110}〈001〉, which is a highly useful orientation for grain-oriented silicon steels because it gives rise to high magnetic permeability along the 〈100〉 direction. To obtain the Goss texture, or {110}〈001〉, in silicon steel sheets, a silicon steel sheet was subjected to an 89 pct reduction in thickness via asymmetric rolling at 750 °C. This step resulted in the well-developed Goss texture. When multiple asymmetrically rolled steel sheets were subsequently annealed, one at 900 °C for 1 hour and the other at 1200 °C for a short period of 5 minutes in a box furnace with air atmosphere, a strong Goss texture was developed in the silicon steel sheets. The texture was measured via X-ray diffraction and electron backscatter diffraction. The magnetization curve of each specimen was measured by the vibrating sample magnetometer and the measured magnetization curve showed the typical soft magnetic characteristics.

Goss Texture Formation by Asymmetric Rolling in Steel Sheet

The Goss texture, or {110}<001>, shows soft magnetic property due to the <100>. Therefore, it is one of the most important texture in Si steels. The Goss texture is one of the shear deformation texture in steel which has bcc structure. During the asymmetric rolling, shear deformation is imposed on steel sheets. To obtain the Goss texture, the carbon and Si steel sheets were asymmetrically rolled by 50-85% reduction in thickness at room temperature and at 770 °C. The asymmetric rolling of steel sheets gave rise to the well-developed Goss texture to them.

Enhanced fatigue crack propagation resistance of Al-Cu-Mg alloy by intensifying Goss texture and refining Goss grains

The effect of intensifying Goss texture and refining Goss grains on the enhancement of fatigue crack propagation (FCP) resistance in an Al-Cu-Mg alloy was systematically investigated. The way to improve fatigue performance mainly includes two steps: intensifying Goss texture component and then refining these Goss grains. Hot rolling at elevated temperature and pre-solution treatment are capable of Goss texture formation. Then large cold rolling reduction can refine grains and obtain more these Goss grains, which increases the twist angle boundary components with their adjacent grains to enhance fatigue crack deflection and FCP resistance. By contrast, refining Brass etc. rolling-oriented grains can increase the tilt angle boundary components and promote fatigue crack growth. And the reason why grain refinement cannot always improve fatigue properties in alloys with micrometer grains can depend mainly on grain orientations and the relative boundary components in this Al-Cu-Mg alloy. Besides, coarse Fe-, Si- and Mn-rich inclusions are detrimental to fatigue properties, but the fine, globular and homogeneous distribution of these particles can improve fatigue properties to some extent.

Deformation, recovery and recrystallization from heterogeneous shear bands in steel sheets

In order to clarify the mechanism of Goss texture formation along shear bands, the effect of cold rolling reduction on shear band formation and crystal orientation within shear bands and annealing texture were investigated in Fe-3%Si {111}<112> single crystals. Shear bands were formed intermittently during cold rolling; shear bands with smaller angles were formed earlier and those with larger angles were formed later. This result supports geometrical softening as a mechanism for shear band formation. Crystal rotation along shear bands became large in proportion to reduction. In calculation crystal rotation in ideal matrix, (111)[11-2], did not reach Goss, however, with consideration of orientation fluctuation the rotation angle exceeded Goss orientation and it coincided with the experimental data. After annealing recrystallized grains along shear bands were mainly Goss grains regardless of cold rolling reduction. The speculated reason for the dominance of Goss during annealing is that Goss cells have a comparatively lower density of dislocations and are surrounded by largely deformed areas.

Goss Texture Evolution of Grain Oriented Silicon Steel by High-Energy X-ray Diffraction

High energy synchrotron diffraction offers great potential to study the recrystallization kinetics of metallic materials. To study the formation of Goss texture ({110}〈001〉) of grain oriented (GO) silicon steel during secondary recrystallization process, an in situ experiment using high energy X-ray diffraction was designed. The results showed that the secondary recrystallization began when the heating temperature was 1,494 K, and the grains grew rapidly above this temperature. With an increase in annealing temperature, the large grains with γ orientation [〈111〉//normal direction] formed and gradually occupied the dominant position. As the annealing temperature increased even further, the grains with Goss orientation to a very large size by devouring the γ orientation grains that formed in the early annealing stage. A single crystal with a Goss orientation was observed in the GO silicon steel when the annealing temperature was 1,540 K.

Goss Texture Formation by Strain Induced Boundary Migration in Semi-Processed Nonoriented Electrical Steels

Semi-processed nonoriented electrical steels are very attractive products whose magnetic properties are significantly improved through annealing treatment in customers plant. The improvement is due to strong Goss texture formation by strain induced boundary migration (SIBM). In order to the effect of temper rolling reduction on the strengthening of Goss texture, temper rolling reduction was changed in the range of 2% to 8%. The annealing times was changed from 10 minutes to 180 minutes. A mechanism of grain growth during SIBM is suggested from our experimental data. In the specimen temper-rolled by 2%, relatively strong {111}&lt;112&gt; texture develops, whereas in the specimens temper-rolled by 4% through 8%, strong Goss texture develops as a result of SIBM during final annealing. It can be found from observed EBSD data that the Goss grains have the lowest stored energy in all temper-rolled specimens, which is confirmed by average image quality value in EBSD measurements. However, for the Goss grains to grow preferentially, stored energy difference between Goss grains and their neighboring grains may have to be higher than a certain critical value.

The Influence of Hot Rolling Technological Parameters on Microstructure of Low Temperature Grain-Oriented Silicon Steel

The process of hot rolling Fe-3.15% Si steel is simulated by Gleeble-3500 thermal mechanical simulator, the influence of finishing temperature, coiling temperature and cooling rates after rolling on microstructure of Fe-3.15% Si steel are mainly researched, and the influence of hot rolled microstructure on Goss texture, secondary recrystallization and magnetic property are analysed. The results show that the nonuniform microstructures of hot rolled strip play an important role in developing the perfect secondary recrystallization. Fe-3.15% Si steel is rough rolled at 1110°C, finished rolled at 880°C, subsequently cooled to 550°C for coiling at rate of 10°C/s, then air cooled to room temperature. The above mentioned process could produce hot-rolled microstructure which are benefit to formation of Goss texture and the development of perfect secondary recrystallization.

Analysis of Micro-texture during Secondary Recrystallization in a Hi-B Electrical Steel

The understanding of Goss texture in Hi-B electrical steels possesses significant industrial and academic value, thus attracts worldwide attention. The prevailing models for sharp Goss texture formation during secondary recrystallization are CSL (coincident site lattice) boundary theory and HE (high energy) boundary theory. These theories stress the key factor of preferred growth and the difference between them only lies in the specific selection manner. This work examined the texture gradient in primarily recrystallized sheet and demonstrated its possible influence on the formation of secondary grains, and then determined the micro-texture during different stages of secondary recrystallization using EBSD (electron back-scattered diffraction) technique, finally analyzed a special type of secondary grains with near Brass orientation, which were detected in the later stage of secondary recrystallization, and discussed its origin and effect in terms of surface energy effect. The results indicate that texture gradient in primarily recrystallized sheet will lead to a multi-stage formation of Goss texture, namely, early stage of secondary grains with various orientations in subsurface region, intermediate stage of preferred growth of Goss grains into center layer and re-grow back to the surface and the final stage of Goss grain growth by swallowing slowly the island grains with the help of H 2 atmosphere.

轧制方向对Fe-3\%Si合金织构演变规律的影响

Sharp Goss texture is crucial for superior magnetic properties of grain oriented silicon steel. The strong initial Goss texture in hot rolled plate will markedly favor the final strong Goss texture. In this paper, different initial textures and microstructures in the surface and center layers of hot rolled plates were established by changing cold rolling direction and their influences on the further evolution of textures and microstructures during first cold rolling, intermediate annealing, secondary cold rolling, decarburizing annealing and secondary recrystallization were investigated. The formation of Goss texture in these specially prepared samples is discussed in details. The results show that the strong differences in initial microstructures and textures vanished gradually as increased times of rolling and annealing, and secondary recrystallization progressed smoothly and nearly independent on rolling directions. The discrepancies of the sharpness of Goss texture and magnetic properties between different samples exhibited minor. The insufficient Goss grains can be compensated through the relatively stronger {111}112 texture formed in all processing stages, although Goss textures in initial samples show different intensities, therefore the rolling direction and initial structure show little influence on secondary recrystallization. Furthermore, results demonstrate the heritage of cube texture and effective elimination of {112}110 texture by 90°rotation of sheet around normal direction (ND).

Texture of Hot Rolled Strip for Fe-3Si Steel Produced by Thin Slab Casting and Rolling

Abstract Fe-3Si steel strip was produced by thin slab casting and rolling (TSCR) process in the laboratory. The microstructure and texture of hot rolled strip by different total reduction and rolling schedules were observed through EBSD technique and X-ray diffraction method. The rule of texture density for the α, ɛ and γ fibers was analyzed. When the total reduction was increased from 82. 9 % to 97. 1 %, the gradient of microstructure and texture for A steel surface layer and center layer was found, {001}<1 ▪0> texture had higher intensity, and {001}<1 ▪0> texture was changed to {110}<001> and {112}<111>. The texture distribution with different reduction schedules for B steel was basically similar, but the Goss texture orientation density and volume fraction for B steel were higher, the hot rolling reduction schedule of C1 was effective for the formation of Goss texture. The research work was useful theoretical basis and reference data to develop electrical steel by thin slab continuous casting and direct rolling technology.

Influence of intermediate annealing on final Goss texture formation in low temperature reheated Fe-3%Si steel

The precipitation behavior of inhibitors and their influence on final Goss texture formation in grain-oriented electrical steels produced by compact strip processing technology with a reheating temperature lower than 1200°C were investigated under two distinct intermediate annealing methods: conventional intermediate recrystallization annealing and a new intermediate decarburizing and recrystallization annealing method without final decarburizing after the second cold rolling. The initiation of secondary recrystallization, the distributions of second phase particles, the final Goss texture, and the grain structure were observed. The new technology could maintain higher inhibitor densities because the deformed matrix could provide higher site densities for inhibitor nucleation before secondary recrystallization, resulting in a relatively higher inhibition effect of the second phase particles. The new technology could also compensate for the disadvantages of fewer inhibitors induced by fewer dissolved Mn and S elements in the matrix during lower reheating temperature for hot rolling. The final sheet produced after the secondary recrystallization annealing obtained stronger Goss texture, larger grain size, and better magnetic properties.

Formation of Goss Texture in Grain Oriented Electrical Steel Sheets Produced by Commercial Compact Strip Processing

The compact strip processing technology and the technologies for conventional grain oriented electrical steels were used to process the low cost grain-oriented electrical steel successfully, in which the reheating temperature for hot rolling was about 1150 oC, and strong Goss texture was obtained after the secondary recrystallization. It is indicated that the density of inhibitor particles produced under the condition of low temperature hot rolling was high enough to induce the necessary secondary recrystallization during final annealing, so that many Goss grains could grow. The mis-orientations of Goss grains to the recrystallization matrix were calculated and observed. High angle boundaries enveloped frequently Goss grains, while the growth of other grains would have the possibility to meet low angle boundaries or low mobile boundaries. Goss grains neighboring larger size grains might be protected by the further precipitation of inhibitor particles in high angel boundaries during the temperature rising stage of the secondary recrystallization and survived somehow after the growth competition.

The Goss Texture Formation in Silicon Steels – Growth Selection or Oriented Nucleation?

The formation of the Goss texture in electrical steels is one of the most distinct phenomena of texture research. Nevertheless, disregarding 60 years of research the mechanisms which let only Goss-oriented grains grow abnormally during a secondary recrystallisation annealing are still not completely understood. The present paper reviews some of the mechanisms of growth selection and oriented nucleation and discusses them in the light of observations made by the authors. We conclude that no mechanism proposed so far is able to explain all experimental observations. This points out the need for the search for a different mechanism.

Orientation dependence of secondary recrystallisation in silicon–iron

Experiments and analyses have been carried out to reach a better understanding of the mechanism of Goss texture formation during the secondary recrystallisation of silicon steel processed by the single cold reduction route. A new experimental approach demonstrated the effect of misorientation on the growth rates of secondary grains and it is shown that these rates are controlled by the proportion of matrix grains having Σ9 CSL relationships to growing secondary grains. It is considered that the Σ9 boundaries have lower energy than general grain boundaries and so are less strongly inhibited by Zener drag. The relative infrequency of Σ9 boundaries around the periphery of secondary grains is seen as evidence for their sacrificial behaviour. Other experiments involving growth of randomly oriented nuclei provide independent support for the important role of Σ9 boundaries during secondary recrystallisation in this steel.