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Leo Kestens - One of the best experts on this subject based on the ideXlab platform.
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modeling the crystallographic Texture changes in aluminum alloys during recrystallization
Acta Materialia, 2011Co-Authors: Jurij J Sidor, Roumen Petrov, Leo KestensAbstract:Abstract The evolution of crystallographic Texture during recrystallization annealing is affected by the hot and cold Rolling parameters. A 6016 Al alloy with various hot band Textures was subjected to conventional Rolling and short time annealing at elevated temperature. Asymmetric Rolling with differential circumferential velocities of the top and bottom rolls was applied to the aluminum alloy under investigation to modify the hot Rolling Texture. The presence of large constituent particles enforces strain heterogeneities during cold Rolling. The influence of particles on the development of recrystallization Textures is discussed based on the experimental data and the results of crystal plasticity simulations. A recrystallization model based on nucleation and growth selection is presented. The driving force for nucleation was accounted for by applying continuum mechanics crystal plasticity models, which allow calculation of the stored energy of plastic strain for specific orientations of the polycrystalline aggregate and for the strain mode under consideration. Crystal misorientations of type 〈1 1 1〉 40° were attributed to enhanced mobility during the growth stage of recrystallization.
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microstructure and Texture evolution during cold Rolling and annealing of a high mn twip steel
Acta Materialia, 2009Co-Authors: Lieven Bracke, Leo Kestens, Kim Verbeken, Jan PenningAbstract:Abstract The microstructure during cold Rolling and annealing of a low-stacking fault energy austenitic Fe–Mn–C alloy was studied by means of electron microscopy. The contribution of both slip and microtwinning to the development of a brass-type cold-Rolling Texture was illustrated. During subsequent recrystallization annealing, a retained Rolling Texture was observed. It was shown that the mechanism behind this phenomenon was based on the nucleation and growth of the recrystallized state without preferred orientation in an energetically relatively homogeneous microstructure.
Olaf Engler - One of the best experts on this subject based on the ideXlab platform.
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Texture and anisotropy in the al mg alloy aa 5005 part i Texture evolution during Rolling and recrystallization
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2014Co-Authors: Olaf EnglerAbstract:Abstract Control of the plastic anisotropy during forming of a metallic sheet requires detailed knowledge about its microstructure and, especially, its crystallographic Texture. In the present study the correlation of Texture and anisotropy is studied in sheets of the Al–Mg alloy AA 5005. A series of different material states with different Textures was produced by back-annealing of cold rolled sheet in the H18 state to the fully soft O condition and, secondly, by subsequent cold Rolling from the soft (O) to the fully hard H19 state. In the present 1st part of this study the evolution of microstructure and Texture in AA 5005 is discussed. Back-annealing of rolled sheet was characterized by recovery followed by recrystallization. These softening reactions were simulated with an analytical model named AlSoft, which was able to reproduce the decline in yield strength and the changes in microstructure and Texture. Upon subsequent cold Rolling the recrystallization Texture in the soft material was gradually transformed back into the typical Rolling Texture orientations. This behaviour, both the sharpening of the Rolling Texture and the decay of the recrystallization Texture from the soft-annealed state, was simulated with the GIA polycrystal-plasticity code. The correlation of the various Textures with anisotropic sheet properties, including Young׳s modulus, yield strength and r -values in uniaxial tensile tests as well as earing upon cup drawing, will be presented in part II of this study.
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effect of through thickness macro and micro Texture gradients on ridging of 17 cr ferritic stainless steel sheet
Steel Research International, 2005Co-Authors: Moo Young Huh, Jae Hyup Lee, Soo Ho Park, Olaf EnglerAbstract:In order to study the formation of ridging in ferritic stainless steel (FSS) sheets, the evolution of the crystallographic Texture was investigated by macro and micro-Texture measurements throughout the thickness of the sheets. The as-received hot band material displayed a pronounced through-thickness Texture gradient with a strong rotated cube orientation in the sheet center layer. The initial Texture of the hot band had a high impact on the formation of the cold Rolling Texture and on the final recrystallization Texture. Modification of the cold Rolling Texture by means of cross-Rolling led to an improvement of the macro and micro-Textures after final recrystallization annealing, which gave rise to an enhanced sheet formability in FSS. Tensile tests of specimens with half thickness revealed that ridging formed in the sheet center was much stronger than that in the surface. This observation was attributed to the more frequent formation of orientation colonies in the sheet center when compared to the sheet surface.
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randomization of the annealing Texture in aluminum 5182 sheet by cross Rolling
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2001Co-Authors: Moo Young Huh, S Y Cho, Olaf EnglerAbstract:Abstract In order to obtain a randomization of the annealing Texture in aluminum AA5182 sheet, the cold-Rolling Texture is modified through introduction of an additional step of cross-Rolling during the deformation. The β-fiber orientations that form during the preceding normal cold-Rolling are unstable under cross-Rolling conditions. Rather, preferred orientations with {011}//ND (α-fiber) develop. A proper control of the respective reduction degrees before and after the cross-Rolling leads to the formation of strong orientation densities along the α-fiber. After recrystallization annealing, the cross-rolled samples depict a very weak, almost random Texture. This Texture randomization is explained by a suppression of both the nucleation and the subsequent growth of the {001}〈100〉 cube orientation which prevails in normally rolled and recrystallized Al sheets. Because of the resulting homogeneous planar anisotropy (R≈1) of the randomly Textured sheets, a better sheet formability was obtained than in conventional sheets with a pronounced cube Texture.
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evolution of the cube Texture in high purity aluminum capacitor foils by continuous recrystallization and subsequent grain growth
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 1999Co-Authors: Olaf Engler, Moo Young HuhAbstract:The evolution of the cube-Texture in high purity aluminum foils which were produced with a high level of cold reduction and a low finishing temperature is tracked by analysis of microstructure and crystallographic Texture. The formation of the cube-Texture proceeds in two consecutive steps. (1) During the first stages of annealing, the deformed substructure is transformed into a very fine grained recrystallized microstructure through extended recovery reactions (continuous recrystallization); the Rolling Texture is retained. (2) Subsequently, the cube-orientation becomes prominent by discontinuous grain growth under consumption of the continuously recrystallized microstructure.
Dierk Raabe - One of the best experts on this subject based on the ideXlab platform.
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effect of strain hardening on Texture development in cold rolled al mg alloy
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2010Co-Authors: Wenchao Liu, Chising Man, Dierk RaabeAbstract:Abstract The hot band of a continuous cast Al–Mg alloy possesses a typical deformed structure and a strong β fiber Rolling Texture. The hot band was heat-treated at 260 °C for 3 h to generate different degrees of strain hardening. The hot band and its counterpart after recovery treatment were cold rolled to different reductions along the original transverse direction. The effect of strain hardening on Texture evolution was investigated by X-ray diffraction. The results show that a high degree of strain hardening reduces the formation rate of the β fiber Rolling Texture.
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Texture and microstructure evolution during cold Rolling of a strip cast and of a hot rolled austenitic stainless steel
Acta Materialia, 1997Co-Authors: Dierk RaabeAbstract:The microstructure and Texture evolution of a strip cast and of a hot rolled austenitic stainless steel (18% Cr, 8.5% Ni) during cold Rolling was studied (maximum thickness reduction Sdld; = 80%). The microstructure of the hot band was homogeneous through the sheet thickness, except that in the centre layer a small volume fraction of martensite appeared. The hot band Texture revealed a through-thickness gradient which was discussed in terms of the shear distribution during hot Rolling. The microstructure of the cast strip showed globular grains with martensite in the centre layer and blocks of austenitic dendrites in the other layers. The formation of martensite was attributed to the deformation of the solidified films in the Rolling gap. The strip cast sample revealed a weak Texture fibre close to {OOI}(uvw) which was interpreted in terms of growth selection during solidification. During cold Rolling in both types of samples the volume fraction of martensite increased up to ~ 50 vol.% (80% reduction). The cold Rolling Texture of the austenite was in both cases characterized by {OIl }(211) and {OIl }(100). The cold Rolling Texture of the hot band was stronger than that of the strip cast sample which was attributed to the influence of the starting Texture and of the grain size. The cold Rolling Texture of the austenite was simulated by means of a Taylor type model considering grain interaction and the so-called card glide mechanism. The martensite Texture was characterized by {211}(0II) and {II I}011). The former component was interpreted in terms of the relaxation of shear constraints. The latter was attributed to selective phase transformation of {OlI}OIl) (austenite) to {332}(113) (martensite) which then rotated towards {JII}(112). The Rolling Textures of the martensite were simulated using a Sachs type deformation model. Copyright © 1997 Acta Metallurgica Inc.
D K Bhattacharya - One of the best experts on this subject based on the ideXlab platform.
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deformation induced transformation Textures in metastable austenitic stainless steel
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2006Co-Authors: Ravi B Kumar, A K Singh, B Mahato, N R Bandyopadhyay, D K BhattacharyaAbstract:Evolution of Texture in metastable austenitic stainless steels under subzero Rolling and cold Rolling conditions is studied. The magnitude of strain-induced α′-martensite phase formed under subzero and subsequent cold Rolling condition found to be larger than only cold Rolling under same amount of deformation. Under both Rolling conditions α′-martensite phase developed similar Texture. On the other hand, the reverted austenite phase produced by ageing treatment has attained its parent cold Rolling Texture in the case of specimens which are only cold rolled. The corresponding reverted austenite phase from subzero and cold rolled specimen has indicated four major Texture components which are typical of fcc metals and alloys. The reversion of α′-martensite observed in this study may be athermal in nature.
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cold Rolling Texture in aisi 304 stainless steel
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2004Co-Authors: Ravi B Kumar, A K Singh, S K Das, D K BhattacharyaAbstract:Evolution of Texture during cold Rolling of austenitic AISI 304 stainless steel is presented here. The annealed steel plate has been unidirectionally cold rolled up to 90% reductions under two different Rolling conditions. Effect of Rolling conditions on transformation of austenite to strain-induced α′ martensite phase and evolution of Texture in both the phases have been studied as a function of Rolling reduction. The X-ray diffraction (XRD) technique has been employed to quantify the volume fractions of austenite and martensite phases and to study the textural development in the steel in rolled conditions. Optical and transmission electron microscopy studies have been carried out to see the microstructural changes due to cold Rolling. Texture in the α′ martensite is found to be governed by the initial Texture of the parent austenite phase according to the Kurdjumov–Sachs relationship, even up to maximum deformation levels.
Satyam Suwas - One of the best experts on this subject based on the ideXlab platform.
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new insights into the development of microstructure and deformation Texture in nickel 60 wt cobalt alloy
Acta Materialia, 2014Co-Authors: R Madhavan, R K Ray, Satyam SuwasAbstract:The present study investigates the critical role of deformation twinning and Bs-type shear bands in the evolution of deformation Texture in a low stacking fault energy Ni-60Co alloy up to very large Rolling strain (epsilon(t) approximate to 4). The alloy develops a strong brass-type Rolling Texture, and its formation is initiated at the early stages of deformation. Extensive twinning is observed at the intermediate stages of deformation, which causes significant Texture reorientation towards alpha-fiber. A pseudo-in-situ electron back-scattered diffraction technique adopted to capture orientation changes within individual grains during the early stages suggests that twinning should be subsequently aided by crystallographic slip to attain alpha-fiber ( parallel to ND) orientations. Beyond 40% reduction, deformation is dominated by Bs-type shear bands, and the banding coincides with the evolution of parallel to ND components. The volume fraction of shear bands is significant at higher strains, and crystallites within the bands preferentially show parallel to ND components. The absence of the Cu {1 1 2} component in the initial Texture, and subsequently during Rolling, indicates that, for the evolution of a brass-type Texture, the presence of the Cu component is not a necessary condition. The final Rolling Texture is a synergistic effect of deformation twinning and shear banding. (C) 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
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asymmetric and symmetric Rolling of magnesium evolution of microstructure Texture and mechanical properties
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2012Co-Authors: Somjeet Biswas, Dongik Kim, Satyam SuwasAbstract:In the present study, asymmetric Rolling was carried out for incorporating a shear component during the Rolling at different temperatures, and was compared with conventional (symmetric) Rolling. The microstructures were investigated using electron back-scatter diffraction (EBSD). The strain incorporated was compared with the help of grain orientation spread (GOS). GOS was eventually used as a criterion to partition the microstructure for separating the deformed and the dynamically recrystallized (DRX) grains. The Texture of the partitioned DRX grains was shifted by similar to 30 degrees along the c-axis from the deformed grains. The mechanism of dynamic recrystallization (DRX) has been identified as continuous dynamic recovery and recrystallization (CDRR). The partitioned deformed grains for the higher temperature rolled specimens exhibited a Texture similar to the room temperature rolled specimen. The asymmetric Rolling introduces a shear component which shifts the Texture fibre by similar to 5-10 degrees from the conventional Rolling Texture. This led to an increase in ductility with little compromise on strength. (c) 2012 Elsevier B.V. All rights reserved.
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microstructure and Texture evolution during accumulative roll bonding of aluminium alloy aa5086
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2011Co-Authors: Shibayan Roy, Satyaveer D Singh, Satyam Suwas, S Kumar, K ChattopadhyayAbstract:Abstract In the present investigation, a strongly bonded strip of an aluminium–magnesium based alloy AA5086 is successfully produced through accumulative roll bonding (ARB). A maximum of up to eight passes has been used for the purpose. Microstructural characterization using electron backscatter diffraction (EBSD) technique indicates the formation of submicron sized (∼200–300 nm) subgrains inside the layered microstructure. The material is strongly Textured where individual layers possess typical FCC Rolling Texture components. More than three times enhancement in 0.2% proof stress (PS) has been obtained after 8 passes due to grain refinement and strain hardening.
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study of Texture evolution in metastable β ti alloy as a function of strain path and its effect on α transformation Texture
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2009Co-Authors: N P Gurao, Ashkar Ali A, Satyam SuwasAbstract:Texture evolution in a low cost beta titanium alloy was studied for different modes of Rolling and heat treatments. The alloy was cold rolled by unidirectional and multi-step cross Rolling. The cold rolled material was either aged directly or recrystallized and then aged. The evolution of Texture in alpha and beta phases were studied. The Rolling Texture of beta phase that is characterized by the gamma fiber is stronger for MSCR than UDR; while the trend is reversed on recrystallization. The mode of Rolling affects alpha transformation Texture on aging with smaller alpha lath size and stronger alpha Texture in UDR than in MSCR. The defect structure in beta phase influences the evolution of a Texture on aging. A stronger defect structure in beta phase leads to variant selection with the rolled samples showing fewer variants than the recrystallized samples.
