Recrystallization Texture Components Research Articles

Creep Deformation and Dynamic Grain Growth in an Interstitial-Free Steel

Dynamic grain growth is demonstrated to be much faster than static grain growth in a body-centered-cubic, interstitial-free steel sheet material at 850 $$\,^\circ {\rm{C}}$$ . Dynamic grain growth occurs during concurrent plastic deformation at elevated temperature, whereas static grain growth occurs during static annealing. Grain growth during steady-state plastic flow in tension at 850 $$\,^\circ {\rm{C}}$$ to a true strain of 0.2 at a true-strain rate of $$10^{-4}$$ $${\rm{s}}^{-1}$$ doubled grain size, while static annealing for the same time produced no increase in grain size. This is described as dynamic normal grain growth (DNGG) because no abnormally large grains were observed. The recrystallized microstructure of the steel demonstrated a log-normal distribution of grain sizes. DNGG produced bimodal grain size distributions that deviate from the theoretical expectation of a simple shift to larger sizes during normal growth. The bimodal distributions contained a remnant of small grains that were not consumed during grain growth. DNGG produced a crystallographic texture that is unique from both the recrystallized material and that produced by lattice rotation alone. DNGG strengthened the $$\{111\} \langle 110 \rangle $$ and $$\{111\} \langle 112 \rangle $$ components of the strong $$\gamma $$ -fiber component in the original recrystallization texture. Lattice rotation from tensile deformation, by contrast, strengthened the $$\alpha $$ -fiber components that intersect the original $$\gamma $$ -fiber.

Temper rolling to control texture and earing in aluminium alloy AA 5050A

The evolution of crystallographic texture during the thermo-mechanical processing of aluminium sheet is accompanied by the development of plastic anisotropy and, most notably, the well-known earing phenomenon. In the present paper we analyse the formation of texture and earing properties in sheets of the Al-Mg alloy AA 5050A (ISO AlMg1.5(D)) along a process route resulting in temper H16 after cold rolling and temper H44 after lacquering. This process route, which is characterized by interannealing in combination with a mild final temper rolling pass, was established for the production of Al packaging sheet with medium strength and very good earing properties. Besides a detailed characterization of the development of microstructure, texture and resultant earing properties during standard processing, measures to improve the earing properties by adapting the ratio of the relevant rolling and recrystallization texture components are addressed.

Influence of Surface Texture and Composition on Graphene Growth by Chemical Vapor Deposition on Cu–Ni Alloys for Field Emission Application

The present investigation is aimed to find a thread between various surface textures of polycrystalline Cu–Ni alloys, in cold-rolled and annealed conditions, and the nature of graphene, grown by the chemical vapor deposition (CVD) method, on these substrates. High-quality graphene grown on Cu–Ni alloys was transferred to various nanostructures, such as CuO nanorods and carbon nanotubes, for field emission application. In this work, Cu–Ni (100Cu–0Ni, 84.65Cu–15.35Ni, 72.6Cu–27.4Ni, and 63Cu–37Ni) alloy buttons were prepared by arc melting, and texture in the samples were engineered by cold rolling (plastic deformation) and annealing (recrystallization) processes. Study of surface texture by X-ray method demonstrates characteristically different deformation and recrystallization texture components, compared to conventional rolling and annealing textures. The evolution of texture has been explained based on the effects of surface friction, shear stress, and addition of Ni. Unusual appearance of {111} orientations, though less in volume, after annealing at 1000 °C, was observed in Cu–Ni alloys through the suppression of cube texture component. The underlying deformation and recrystallization mechanisms are explained through the changes in strain hardening, extended recovery, and continuous recrystallization effects. The effects of Ni content are correlated with the number of graphene layers, while an increase in the fraction of {111} orientations could be linked with defect density in graphene layers. Results of the present study will be motivating for selection of various polycrystalline Cu–Ni alloys, with different surface textures, for controlling quality of graphene, synthesized by the chemical vapor deposition method.

Microstructure evolution and mechanical properties of double-sided friction stir welding between AA6061-T6 and AA7075-T651

The present study appraises the effect of tool rotation direction during dissimilar double-sided friction stir welding of AA6061–AA7075 thick plates. The mechanical strength, fracture behavior and the microstructure evolution for the joints are studied. Sound joints without defect and higher strength was achieved for the joint wherein tool rotation in the second weld is provided in the reverse to that of the first weld. Electron backscatter diffraction of welded joints revealed finer grains at the weld center than observed below the tool shoulder affiliated to high degree of deformation/strain. Pole figures revealed the dominance of high shear texture B/B¯ and C components at the weld center. Orientation distribution function revealed the presence of strong intensity recrystallization texture components Cube {001}<100>, Goss {110}<001> and P {011}<112> at the weld center.

Texture transition in friction stir processed Al powder compact

Green Al powder compacts of commercial purity with random orientation were subjected to single pass friction stir processing (FSP) with different tool rotational and traverse speeds. The evolution of crystallographic texture obtained from large area electron back scattered diffraction were compared with the bulk texture of the nugget zone characterized using synchrotron diffraction. Evolution of different deformation and recrystallization texture components were discussed. While the grain size distributions were found to be independent of process parameters, the texture components and their strength of the FSPed samples were strongly influenced by the process parameters. Continuous dynamic recrystallization (CDRx) was found to be the primary restoration mechanism for most of the processing conditions leading to a bi-modal misorientation distribution. The possible relations between different texture components and the appearance or suppression of bimodal misorientation distributions were discussed. Restoration mechanism changed to discontinuous dynamic recrystallization (DDRx) with the evolution of cube component at the stir zone along with random misorientation distribution. Dominance of a particular restoration mechanism depends on strain, strain rate and temperature attained during the processing.

Recrystallization texture development in rare-earth (RE)-doped non-oriented silicon steel

High-grade non-oriented silicon steel with higher permeability and lower core loss has become the pursed target with the rapid development of electrical machines. The effects of rare-earth (RE) element on recrystallization texture in RE-doped Fe-3.1 wt.% Si-1.2 wt.% Al non-oriented silicon steel were investigated by macro- and micro-texture analyses. Nonlinear variation of recrystallization texture with RE element content was observed. In the competition among main recrystallization texture components, favorable {113} and λ fiber ( //ND) are strengthened and unfavorable γ fiber is evidently decreased by the addition of RE element, whereas the effect of RE element is reversed by excess RE element. The recrystallization texture development is determined by RE-affected nucleation and grain growth in terms of grain boundary migration related to segregation and inclusion. The properly inhibited grain boundary mobility can promote favorable recrystallization texture by the improved nucleation and efficient grain growth.

Microstructure and texture development in AA3003 aluminium alloy

For good deep drawability in aluminium and its alloys, a proper balance of deformation and recrystallization texture components is essestial in the final material. This balance of deformation and recrystallization texture can only be achieved by properly controlling the thermo-mechanical processing of the alloy. In the present study, microstructure and texture development during casting, hot rolling, cold rolling, and annealing of an aluminium alloy (AA3003) is investigated. The cast microstructure showed large grains with average grain size 111 μm and presence of Al-Fe-Si particles along the grain boundaries. After hot rolling (500 °C (±10 °C)) and cold rolling, these second phase particles which consisted primarily of Fe:Si in a ratio 10:1 in the as-cast microstructure fragmented into smaller particles and had higher percentage of Fe, Mn, and Si. After hot rolling and cold rolling, microstructure showing banded structure along the rolling direction i.e. elongated grains. Annealing at 450 °C for 16 h produced microstructure with uniform average grain size 22 μm and second phase particles with non-uniform size distribution. The initial as-cast AA3003 alloy had a very weak cube texture ({100}<100>, 3.4 % volume fraction). After cold rolling, strong Brass ({110}<112>), Copper ({112}<111>) and S ({123}<634>) components formed. After cold rolling, cube decreased and did not improve significantly even after annealing at 450 °C. The developments in annealing texture is explained on the basis of particle stimulated nucleation.

Workability of High-Strength Automobile Steel at High Temperatures Using Hot Processing Maps and Electron Backscatter Diffraction

Hot deformation behavior of a high-strength steel Docol 1500 Bor was investigated by compression tests on a thermal–mechanical simulator Gleeble 3500. The workability of tested steel was analyzed by building processing maps at three strains based on the test results of flow stresses. The essential deformation mechanism was further studied based on the deformation texture analysis on a scanning electronic microscope with a TSL-OIM™EBSD system. It was found that that strain can affect the workability of the tested steel remarkably. At the engineering strain of 0.6, obvious textures in martensite mainly include recrystallization textures //ND and other texture components //RD and {001} , etc. Dynamic recrystallization and recrystallization texture component //ND in deformed austenite can contribute to increasing the workability of a steel Docol 1500 Bor. Finally, the optimized deformation conditions of the tested steel were obtained.

Texture evolution and mechanical properties of Al–Mg–Si alloys at different intermediate annealing temperatures

Intermediate annealing treatment produces different effects on the state of particles in Al–Mg–Si alloy sheets, thereby affecting their recrystallization textures and formability. To improve the formability of the sheets, the effects of different intermediate annealing temperatures on the texture evolution and mechanical properties of these sheets for automotive applications were studied using optical microscope (OM), scanning electron microscope (SEM) and tensile tests. The results reveal that intermediate annealing temperature has a significant influence on the recrystallization textures and average plastic strain ratio (r). After solution treatment, all the alloy sheets possess similar recrystallization texture components comprising of cubeND {100} and P {011} orientations, whereas a characteristic strong cube-oriented {100} texture is observed only in the alloy annealed at a temperature of 380 °C. However, in comparison with the alloy not annealed, and the alloy annealed at 550 °C, the alloy annealed at 380 °C possesses a lower average r value. Furthermore, the relationship between textures and r value was analyzed by using the Taylor full constraints model in this study.

Influence of grain size before cold rolling on development of crystallographically equivalent main texture component in recrystallization texture of 3% Si-Fe

3%Si-Fe sheet produced by high cold rolling reduction over 80% has strong {111}<112> recrystallization texture. This orientation has two crystallographically equivalent orientations such as (111)[1 -2 1] and (111)[-1 -1 2]. However, there are a few previous works in which these orientations are investigated separately. In the present study, the recrystallization behavior of the crystallographically equivalent orientations of {111}<112> was investigated using two samples with different grain sizes before cold rolling. Both recrystallized samples had strong {111}<112> component texture. The sample with a small grain size before cold rolling had almost the same fraction of each equivalent orientations, while the sample with a large grain size had substantially different fractions of each equivalent orientations. Spatial distribution of two crystallographically equivalent orientations in the sample with a small grain size before cold rolling was almost homogeneous, however that in the sample with a large grain size before cold rolling was inhomogeneous. It is considered that these differences are explained by the assumption that a certain large grain before cold rolling will generate only single crystallographically equivalent orientation after cold rolling and annealing.

Effect of SiC nanoparticles on the microstructure and texture of friction stir welded AA2024/AA6061

In the present study, the effect of SiC nanoparticles on the microstructure and texture evolution of friction stir welded AA2024/AA6061 dissimilar joint investigated. The results showed that the SiC nanoparticles homogeneously dispersed in the aluminum matrix. The Al/SiC interfaces had a good quality of bonding between particles and matrix. It was found that the new recrystallized aluminum grains tend to nucleate and grow on the 11¯1 crystal plane of SiC nanoparticle (1¯1¯1Al facet on 11¯1SiC surface). The average grain size in the stirred zone (SZ) decreased to 7.4 μm owing to the grain refinement through the occurrence of both dynamic and static recrystallization. Most grains in the center of the stirred zone grown due to the occurrence of continuous grain growth (CGG) mechanism after the stirring. Moreover, the incorporation of SiC nanoparticles led to a reduction of 26% in the mean grain size of the SZ. The average size of the precipitate particles in the stirred zone was much smaller than the thermo-mechanically affected zone (TMAZ) owing to the dissolution of precipitates during stirring and reprecipitation during cooling. In addition, the grain size of the stirred zone on the advancing side was lower than the retreating side (2.6 μm vs. 9.7 μm). The results revealed a weaker texture after FSW compared to the initial samples. The SiC nanoparticles largely suppressed the rotation of the {001}〈100〉 oriented new grains through particle pinning effect. Unlike the advancing side, there was no recrystallization texture component on the retreating side.

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.

Four unusual texture transitions in high purity copper during cold deformation followed by quenching

The effect of cold rolling and subsequent quenching on the texture evolution of pure copper were investigated. The copper sheets processed by 40%, 50%, 60%, 70%, 80%, and 90% thickness reductions of cold rolling. The crystallographic texture was characterized by x-ray diffraction (XRD). Four unusual texture transitions including: (1) Copper-type to Brass-type at 50%, (2) deformation-type to recrystallization-type at 60%, (3) Brass-type to Copper-type at 70%, and (4) recrystallization-type to deformation-type at 90% were observed. The texture after 40% and 70% deformations was very similar. Also, the strong deformation and recrystallization components produced at 80% rolling reduction. In addition, with increasing thickness reduction onwards 80%, the main deformation texture orientations significantly strengthened. Finally, the recrystallization texture component completely eliminated at 90% deformation.

The effect of microstructure on the mechanical properties of friction stir welded 5A06 Al Alloy

The effect of grain size, grain orientation and precipitates on mechanical properties of friction stir welded 5A06 aluminum alloy was investigated with varying rotation speeds. The precipitation behavior and grain coarsening were discussed. Recrystallization occurred in the weld zones and recrystallization texture components were replaced by the shear texture components with increased rotation speeds. The development of shear texture, precipitates dissolution, and dislocations pinned by precipitates may result in the coarsening of the grains in the weld zones at higher rotation speeds. The effect of grain size on hardness is consistent with Hall-Petch relationship. All the welds fractured in the boundary between TMAZ and the HAZ at the AS due to the dislocations pinned by the precipitates and the sharp change of microstructure at the AS.

Development of microstructure and texture during single and multiple pass friction stir processing of a strain hardenable aluminium alloy

In the present study, microstructure and texture development during single and multiple pass friction stir processing (FSP) of a strain hardenable wrought AlMg alloy (AA5086) was investigated. Subtle differences were observed while comparing with heat treatable alloys in the nucleation mechanism of the recrystallized microstructure observed in the nugget zone. Strain induced boundary migration was the dominant mechanism of microstructure evolution in the alloy, which influenced the crystallographic texture development by weakening it. Micro-texture measurements reveal variations in the crystallographic texture along the thickness of the sample. Recrystallization texture components were observed in the nugget zone indicative of a pronounced static recrystallization in the alloy as compared to the heat treatable alloys. Bulk texture measurements within the nugget zone of the optimally processed sample reveal a relatively dominant C component of shear texture. Average grain size in the nugget zone remained the same and the bulk crystallographic texture components were retained during multiple-pass FSP. The lower strain energies involved and the enhanced recovery processes due to the high temperature materials processing of the alloy during FSP resulted in a stable microstructure and texture. In summary, FSP could be promoted as a competent and suitable secondary processing technique for the bulk production of ultra-fine-grained materials in strain hardenable aluminium alloys.

Microstructure Refinement and Mechanical Properties of 304 Stainless Steel by Repetitive Thermomechanical Processing

Repetitive thermomechanical processing (TMP) was applied for evaluating the effect of strain-induced α′-martensite transformation and reversion annealing on microstructure refinement and mechanical properties of 304 austenitic stainless steel. The first TMP scheme consisted of four cycles of tensile deformation to strain of 0.4, while the second TMP scheme applied two cycles of tensile straining to 0.6. For both schemes, tensile tests were conducted at 173 K (− 100 °C) followed by 5-minute annealing at 1073 K (800 °C). The volume fraction of α′-martensite in deformed samples increased with increasing cycles, reaching a maximum of 98 vol pct. Examination of annealed microstructure by electron backscattered diffraction indicated that increasing strain and/or number of cycles resulted in stronger reversion to austenite with finer grain size of 1 μm. Yet, increasing strain reduced the formation of Σ3 boundaries. The annealing textures generally show reversion of α′-martensite texture components to the austenite texture of brass and copper orientations. The increase in strain and/or number of cycles resulted in stronger intensity of copper orientation, accompanied by the formation of recrystallization texture components of Goss, cube, and rotated cube. The reduction in grain size with increasing cycles caused an increase in yield strength. It also resulted in an increase in strain hardening rate during deformation due to the increase in the formation of α′-martensite. The increase in strain hardening rate occurred in two consecutive stages, marked as stages II and III. The strain hardening in stage II is due to the formation of α′-martensite from either austenite or e-martensite, while the stage-III strain hardening is attributed to the necessity to break the α′-martensite-banded structure for forming block-type martensite at high strains.

Microstructural evolution of friction stir welded SAF 2205 duplex stainless steel

Microstructure evolution of SAF 2205 duplex stainless steel (DSS) was investigated in friction stir welding (FSW) process at welding speed of 50 mm/min and rotational speed of 400 rpm. Microstructural observations were carried out using optical microscopy and scanning electron microscopy equipped with electron back scattered diffraction (EBSD) system. The results showed that grain refinement took place and simple shear texture components developed in each constituent phases of ferrite and austenite in stir zone (SZ). Beside the simple shear texture components, common recrystallization texture components of cube ({001}〈100〉), Goss ({011}〈100〉), S ({123}〈634〉), P ({011}〈122〉), and Q ({013}〈231〉) were recognized to exist in the austenite phase. These results confirmed the occurrence of the continuous dynamic recrystallization (CDRX) in both phases as well as static recrystallization (SRX) in austenite phase.

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 deformation path on texture and tension properties of submicrocrystalline Al-Mg-Si alloy fabricated by differential speed rolling

The work investigated the effect of deformation path on texture and tension properties of submicrocrystalline Al-Mg-Si alloy sample processed by differential speed rolling (DSR). DSR was performed on the present samples rotated between passage utilizing three paths, such as no rotation, rotations along the transverse and rolling axes toward deformation direction in order to understand the roles of the different characteristics of macro-shear. When both no rotation and rotation along the transverse axis were applied, high strength but low ductility would be obtained due to the presence of fine grains together with lamellar bands. A good combination of strength (∼312 MPa) and ductility (∼7.4%) was attained by means of rotation along the rolling axis, giving rise to the conjugation of macro-shear bands. This was explained in relation to the interpretation of recrystallization texture components.

Controlling grain structure and texture in Al-Mn from the competition between precipitation and recrystallization

The recrystallization behaviour of Al-Mn alloys (AA3xxx series alloys) is affected by randomly distributed dispersoids present before annealing, by dispersoids precipitated at grain/subgrain boundaries before the onset of recrystallization, and by dispersoids concurrently precipitated during recrystallization. In this study, the effects of these three populations of dispersoids on the recrystallization behaviour of a cold rolled AA3xxx alloy were analysed and compared using four temperature-time paths to different target temperatures. Changing the temperature-time path modifies the extent of recovery, the dispersoid structures, as well as the absolute recrystallization temperature, which then influences the final grain structure and recrystallization texture. In particular, an in-depth investigation on how different populations of dispersoids affect the main recrystallization texture components of AA3xxx alloys, i.e., P{011}〈566〉, ND-Cube {001}〈310〉, and Cube {001}〈100〉, has been carried out. The results clearly show that, as compared to isothermal annealing, annealing with more elaborate heating and annealing schedules (temperature-time paths) all lead to increased strength of the P texture component and decreased intensities of both the Cube and ND-rotated Cube texture components. The increase of P texture strength and average grain size is most significant when recrystallization occurs concurrently with precipitation. The controlling mechanisms behind this behaviour and the possibility to use them to tailor the grain structure and texture of similar alloys are further discussed.