Beginning Of Recrystallization Research Articles

Strong {411}<148> Recrystallization Texture in Fe–Si–Ni–Al–Mn High‐Strength Non‐Oriented Electrical Steel

This study is focused on, elucidating texture evolution during the different process stages of a new Fe–Si–Ni–Al–Mn high‐strength non‐oriented electrical steel and the formation of the {411}<148> grains whose formation reduces the γ texture content and improves the magnetic properties. The strongest texture component of the new of high‐strength non‐oriented electrical steel type is {111}<110> in the grain nucleation stage. Nevertheless, the {411}<148> orientation is the main orientation component in the grain growth stage. The {411}<148> grains nucleate at the γ oriented and {001}<110>‐{223}<110> grains boundaries or intracrystalline shear bands of γ‐fiber grains. There is a competitive relationship between the nucleation of {411}<148> grains, Cube, Goss, and γ‐fiber grains at the beginning of recrystallization. The combined effect of the size advantage of {411}<148> grains, the influence of orientation pinning on other major oriented grains, and the high mobility of {411}<148> grain boundaries generate a significant {411}<148> recrystallized grain after the annealing process. The key mechanism of {411}<148> texture formation is attributed to the selective growth theory in Fe–Si–Ni–Al–Mn high‐strength non‐oriented electrical steel.

Оценка уровня упрочнения стружки из алюминиевого сплава, предназначенной для последующей обработки давлением

Introduction. It is noted that the chip is an undesirable type of metal scrap, because it has a developed surface, which creates conditions for more intense interaction with the surrounding atmosphere. This creates conditions for oxidation and gas saturation, especially at elevated temperatures typical of remelting processes. Therefore, the process of chip utilizing is considered, bypassing the remelting stage. The aim of the work is to establish the level of work hardening of chips during the processing of aluminum alloys and to predict its effect on the subsequent processing process. Research methods: to assess the deformed state, the finite element method was applied, implemented in the RAPID-2D software package. The sequence of actions included the creation of the initial shape of the deformation region and the configuration of the tool. The mutual displacement of the tool and the deformable material is specified using the corresponding boundary conditions. The deformable medium is a viscous-plastic material with power-law hardening, the physical and mechanical properties correspond to an aluminum-magnesium alloy. Results and discussion: the solution obtained shows that the degree of shear deformation in the chips can reach a value of more than 2. In this case, a higher level of deformation is localized on the side of the convex part of the chip. The comparison of the solution with those obtained earlier by other authors is carried out and its similarity is shown. In the considered solution, the difference in the degree of work-hardening of the chips along its thickness is 36 %. A variant of the sequence of processing the workpiece first by cold deformation, and then by cutting is considered. The field of application of the results of the work is the development of methods for the processing of technogenic formations. Conclusions. During the cutting process, the plastic deformation of the chips reaches significant values. In this paper, the difference in the degree of shear deformation in the chip thickness is established, depending on the proximity of the cut layer to the surface of the cutting tool. It is proposed to take this difference into account at the subsequent stages of chip processing. The presence of the marked inhomogeneity of mechanical properties leads to consequences in the form of an inhomogeneous distribution of the temperature of the beginning of recrystallization during subsequent operations of heat treatment or hot deformation treatment. The principle of additivity of the degree of deformation obtained by the metal at the stage of plastic shaping of the workpiece and the shaping of the chip itself is introduced.

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°.

Development of Goss texture in Al–0.3%Cu annealed after heavy rolling

The evolution of the microstructure and texture during annealing has been studied in the center layer of 95% cold rolled Al–0.3%Cu with a large initial grain size. The cold-rolled condition is characterized by a strong Brass texture component and a deformed microstructure comprising lamellar structures intersected by a large number of shear bands. Recrystallization and precipitation take place during annealing at 200 °C, and a strong Goss texture develops. In the beginning of recrystallization, Goss oriented grains nucleate preferentially at the shear bands. At a later stage of recrystallization, new Goss nuclei can appear in regions where lamellae of the dominant Brass component are interspersed with Goss-oriented subgrains. When recrystallization is almost complete, recrystallized Goss-oriented grains grow into grains of other orientations, which results in a rapid increase in the average grain size of Goss-oriented grains and strengthening of the Goss texture. As a result, new low angle boundaries are formed between Goss-oriented grains in this strongly textured material.

Effects of structural heterogeneity of nanostructured copper on the evolution of the sizes of recrystallized grains during annealing

Recrystallization in copper deformed by dynamic plastic deformation was investigated using electron backscatter diffraction. The recrystallized grains show a broad size distribution. The kinetics of grains of different sizes is observed to be different: In the beginning of recrystallization, the area fraction of small recrystallized grains increases rapidly. At later stages of recrystallization, the area fraction of small recrystallized grains is stable, while the area fractions of medium and large recrystallized grains increase. Correlation between the broad grain size distribution (and its evolution) and the heterogeneous deformed microstructure is discussed.

Investigation on Work Hardening Behavior of Nickel-Base Superalloy during Hot Working Process by EBSD

The Nickel-base superalloy samples were prepared by the isothermal forging in strain rate 1s-1 at deformation temperature 1070°C with different strain levels. The EBSD was carried out in order to investigate the microstructural changes that took place due to strain level. The result is the samples has no apparent dynamic recrystallization behavior in hot deformation in 1s-1 at 1070°C. The true stress-true strain curve has two peak values in the strain level of 20% and 60%, and one valley value in the strain level of 50%. The first peak value is result in the activation of slip system and the beginning of recrystallization and the second peak value of the true stress-true strain curve is result in the inhibition of activation of slip system and grain growth by the dislocation density. The work hardening behavior of P/M Nickel-base superalloy may be related to the size ratio of γ’ phase with grain size.

Evolution of cube texture in strip-cast non-oriented silicon steels

Texture evolution in Fe-1.3%Si steels with ultra-high magnetic induction produced by strip casting, cold rolling and annealing was investigated using macro-/micro-texture analysis. A new and strong {1 1 0} fiber has been founded in thin as-cast sheets. The in-grain shear bands with the Cube orientation can be observed in deformed {1 1 0}〈1 1 0〉 grains after cold rolling. The new Cube grains are mainly nucleated and grow within those shear bands at the beginning of recrystallization and consequently determine the overall annealing texture.

Investigation on the Recrystallization Mechanism in Warm-Rolled Ti-IF Steel

The nuclei orientation, the nucleation site at the early stage of recrystallization, and the growth mechanism of the nuclei have been studied by EBSD analysis in Ti-IF steel during direct annealing after warm rolling. It is concluded that the formation of the recrystallization texture is dominated by the oriented nucleation mechanism. The recrystallized nuclei with γ-orientation emerged preferentially at the beginning of recrystallization and preferred to form in the deformed bands with γ-orientation and on the boundaries between γ- and α-orientations. The recrystallized grains first consumed their neighboring γ-oriented matrix; and then consumed the α-oriented deformed bands at the late stage of recrystallization, leading to strong γ-fiber.

In-Situ Annealing Study of Transformation of α and γ Texture of Interstitial-Free Steel Sheet by High-Energy X-Ray Diffraction

High-energy synchrotron diffraction offers great potential for experimental study of recrystallization kinetics. An experimental design to study the recrystallization mechanism of interstitial-free (IF) steel was implemented. The whole annealing process of cold-rolled IF steel with 80% reduction was observed in situ using high-energy X-ray diffraction (HEXRD). The results show how the main texture component of IF steel change, i.e. the α [<110>// rolling direction (RD)] fiber texture decreases and the γ [<111>//normal direction (ND)] fiber texture increases. The important part of the α fiber texture is that both the {100}<011> and {112}<011> texture decrease at the beginning of recrystallization. The γ fiber texture increases at the early stage of recrystallization which stems from the increase of {111}<112>. Nevertheless, the {111}<110> does not change after recrystallization. The dynamic evolution of the main texture components {100}<011>, {112}<011>, {111}<112> and {111}<110> is given by in-situ HEXRD.

EBSD Investigation on the Primary Recrystallization in Warm Rolled Ti-IF Steel

The nucleus orientations and the nucleation sites at the early stage of recrystallization were studied by EBSD analysis in Ti-IF steel during direct annealing after warm rolling. It is concluded that the formation of the recrystallization texture is dominated by oriented nucleation mechanism. The recrystallized nuclei with γ-orientation emerge preferentially at the beginning of recrystallization and prefer to form inside the γ-oriented deformation bands and on the boundaries between γ and α-oriented bands.

Evolution of Deformation and Recrystallization Textures in High-Purity Ni and the Ni-5 at. pct W Alloy

An attempt has been made to study the evolution of texture in high-purity Ni and Ni-5 at. pct W alloy prepared by the powder metallurgy route followed by heavy cold rolling (~95 pct deformation) and recrystallization. The deformation textures of the two materials are of typical pure metal or Cu-type texture. Cube-oriented (\( \left\{ {00 1} \right\}\left\langle { 100} \right\rangle \)) regions are present in the deformed state as long thin bands, elongated in the rolling direction (RD). These bands are characterized by a high orientation gradient inside, which is a result of the rotation of the cube-oriented cells around the RD toward the RD-rotated cube (\( \left\{ {0 1 3} \right\}\left\langle { 100} \right\rangle \)). Low-temperature annealing produces a weak cube texture along with the \( \left\{ {0 1 3} \right\}\left\langle { 100} \right\rangle \) component, with the latter being much stronger in high-purity Ni than in the Ni-W alloy. At higher temperatures, the cube texture is strengthened considerably in the Ni-W alloy; however, the cube volume fraction in high-purity Ni is significantly lower because of the retention of the \( \left\{ {0 1 3} \right\}\left\langle { 100} \right\rangle \) component. The difference in the relative strengths of the cube, and the \( \left\{ {0 1 3} \right\}\left\langle { 100} \right\rangle \) components in the two materials is evident from the beginning of recrystallization in which more \( \left\{ {0 1 3} \right\}\left\langle { 100} \right\rangle \)-oriented grains than near cube grains form in high-purity Ni. The preferential nucleation of the near cube and the \( \left\{ {0 1 3} \right\}\left\langle { 100} \right\rangle \) grains in these materials seems to be a result of the high orientation gradients associated with the cube bands that offer a favorable environment for early nucleation.

EBSD Characterization of Pure Iron Deformed by ECAE

Polycrystalline iron was deformed by eight ECAE passes using the route Bc to a total strain of 9.2. After deformation the material was annealed at temperatures up to 800oC. Scanning electron microscopy (SEM) and high-resolution electron backscatter diffraction (EBSD) were used to characterize both deformed and annealed structures. In the as-deformed state, the mean grain size is 650 nm and the volume fraction of high angle boundaries (VHAB) is 56%. Upon annealing there is a pronounced softening above 300oC. At the beginning of recrystallization, at about 400oC, the VHAB increases to 71%. The results indicate that discontinuous recrystallization is the main softening mechanism in severely deformed iron.

On recrystallization texture formation in polycrystalline fcc alloys with low stacking fault energies

Abstract The texture and microstructure transformations during the annealing of highly cold-rolled silver, α-brass and phosphorus copper were studied using electron microscopy and calorimetry. The results imply that recrystallization is a superposition of several local processes which proceed in two stages. In all materials analyzed, the first stage is governed by oriented nucleation, comprising the nucleation of new grains in the areas of localized strain and their further growth accompanied by the generation of recrystallization twins. The orientation distributions of nuclei and the new grains of all materials analyzed have certain features in common at the beginning of recrystallization. The second stage in phosphorus copper is governed by oriented nucleation, while in silver and in α-brass, it is dominated by oriented growth of grains, characterized by low orientation pinning.

Effect of processing variables on cube texture formation in powder metallurgically prepared Ni and Ni–W alloy tapes for use as substrates for coated conductor applications

Development of textures have been studied in powder metallurgically prepared pure Ni and Ni–5 at.% W alloy after heavy cold rolling (∼95% reduction in thickness) and annealing for use as substrates for coated superconductor applications. The cold rolling textures of the two materials do not show any significant difference. However, Ni–5 at.% W alloy is found to develop a much sharper cube texture after annealing which indicate the beneficial role of W in increasing the cube volume fraction in Ni. W increases the volume fraction of the cube component by decreasing the volume fraction of the rolling direction (RD)-rotated cube grains. Partial recrystallization studies clearly indicate that in contrast to pure Ni sharp cube oriented grains form in Ni–5 at.% W alloy right from the beginning of recrystallization. A near 100% cube texture is obtained in Ni–5 at.% W alloy by an optimized two stage rolling (TSR) procedure followed by annealing at 1350 °C.

Recrystallization textures of powder metallurgically prepared pure Ni, Ni–W and Ni–Mo alloy tapes for use as substrates for coated superconductors

Development of cube texture after heavy cold deformation and annealing has been studied in powder metallurgically prepared pure Ni, Ni–5at.%Mo and Ni–5at.%W alloys for use as substrates for coated superconductor applications. Two grades of Ni powder with different purities have been used to prepare the initial materials. Addition of W and Mo is found to be beneficial in increasing the volume fraction of the cube component, irrespective of the purity of the Ni powder used. W particularly increases the volume fraction of the cube component in Ni by decreasing the volume fraction of the RD (rolling direction)-rotated cube grains. Studies on partially recrystallized samples indicate that in contrast to pure Ni, in Ni–5at.%W alloy the recrystallized grains are mostly cube oriented right from the beginning of recrystallization.

Proportion of recovery and recrystallization during interpass times at high temperatures on a Nb- and N-bearing austenitic stainless steel biomaterial

Softening between deformations was determined by double torsion tests, metallographic examination and electron backscattered diffraction. High levels of softening of as much as 60% can be promoted by recovery during interpass times, before and at the beginning of recrystallization. The restoration promoted by recovery during recrystallization was analyzed through the evolution of low angle grain boundary fractions.

Improving the properties of cold-rolled Al–6%Ni sheets by alloying and heat treatment

The mechanical properties of a cold-rolled binary eutectic Al–Ni alloy can be considerably improved by additional alloying with Zr and heat treatment of a billet. Two-stage annealing of billets results in the favourable morphology changes in the eutectics structure and in the substantial hardening with participation of Al 3Zr dispersoids. The cold-rolled material starts to soften only at temperatures as high as 350 °C. The main reason of softening at higher temperatures is the beginning of recrystallization with the formation of subgrains and grains of submicron size.

Crystallographic orientations of Ni 3Al-based aluminide

Inverse pole figures have been plotted to determine preferred crystallographic orientations in a powder-compacted Ni 3Al aluminide prealloyed with Fe, Ti and B. The main textural components, although weak, were noticeably altered by cold deformation, recrystallization and high-temperature deformation. Cold uniaxial compression generated a pronounced (110) orientation and the less common (112) orientation. The existence of the latter orientation was ascribed to the cubic→tetragonal structural transformation (L1 2→DO 22). The beginning of recrystallization was characterized by a string of (113)+(112)+(111) orientations. However, after prolonged periods of annealing, the (113) orientation diminished, whereas the (111) and (112) orientations became stronger, perhaps due to preferred orientational growth. Deformation at high-temperature gave rise to strong (111) and (100)+(112) orientations. It was found that disordering and dynamic recrystallization simultaneously control high-temperature deformation.

Dislocation emission in A1 during recrystallization

The dislocation structure evolution during isothermal recrystallization of Al has been followed by means of internal friction, modulus defect and X-ray diffraction analyses accompanying the microscopical observations. Many peaks ofQ −1 and of modulus defect and X-ray diffraction line width have been found, both in nucleation and grain growth, all referable to dislocations. The first of these peaks, at the beginning of recrystallization, presents recovery characteristics, different from those shown by the subsequent, secondary peaks. Secondary peaks are interpreted in terms of dislocation emission from grain boundaries, whereas the first peak appears connected with subboundaries, walls present in the initial stages of recrystallization.

Ni-30%Cu合金の温間加工と再結晶粒度

The effect of working temperature before annealing on the recrystallization of Ni-30%Cu alloy was investigated by Vickers hardness measurement, optical microscopy and transmission electron microscopy. As the working temperature increased, the beginning of recrystallization was retarded and the grain size of recrystallized structure became finer. However, the activation energy for recrystallization was not affected so much by the working temperature, except for room temperature. Finer recrystallized grains were obtained at a higher working temperature and a lower annealing temperature. It is considered that the refinement of structure due to warm working is attributed to the dislocation cell structure.