Recrystallization and Grain Growth

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Authors: Dorothée Dorner, Ludger Lahn, Stefan Zaefferer
Abstract: A silicon steel single crystal with {110}<001> Goss orientation was cold rolled up to 89 % thickness reduction and subsequently annealed. The evolution of the macroscopic cold rolling texture was investigated by x-ray diffraction. Local orientation relationships and the microstructure around and within Goss grains of deformed and annealed samples were analysed using the electron backscatter diffraction (EBSD) technique. During cold rolling a texture consisting of two strong {111}<112> components and a minor {110}<001> Goss component develops. After primary recrystallisation the texture is characterized by a strong Goss component. Goss-oriented grains that remain after high deformation are considered to be the origin for the primary recrystallisation texture.
Authors: Ph. Gerber, S. Jakani, Thierry Baudin, Marie Helene Mathon, Richard Penelle
Abstract: Wire-drawn Electrolytic Tough Pitch copper deformed at moderate strain has been investigated with Electron Back Scattered Diffraction in a Scanning Electronic Microscope in order to evaluate the recrystallization mechanisms at the meso-scale. Experimentally, it has been shown that the static recrystallization takes place first in the highly deformed and misoriented areas, in the intermediate regions of the wire. The grains related to the <100> fiber nucleate and grow first in these regions, but some other orientations (including the <111> oriented grains) - that have a combined nucleation/growth potential - develop in second time. The annealing twinning is active from the beginning of the recrystallization and tends to randomize the final recrystallization texture.
Authors: Ane Martínez-de-Guereñu, F. Arizti, Isabel Gutiérrez
Abstract: A cold rolled low carbon steel has been annealed at sufficiently low temperatures (300 to 500 °C) in order to promote recovery without interaction with recrystallization. The recovery kinetics has been followed by using magnetic coercive field (Hc) measurements. The microstructural changes associated with the observed decrease in Hc, produced by the recovery, have been analysed by TEM observations. The experimental data have been adequately modelled using various formulations reported in the literature. The kinetics of the dislocation hardening contribution to the yield stress has been derived from the kinetics of the coercive field, taking into account the existing linear relationship between both variables.
Authors: Dorte Juul Jensen, M.D. Lund, A.W. Larsen, Jacob R. Bowen
Abstract: Possible variations in recrystallization kinetics from the sample surface to the center have been investigated in 90% homogeneously cold rolled aluminium (AA1050). It was found that whereas the average growth rates are quite similar, the nucleation characteristics are different at the surface and in the bulk.
Authors: Satoru Kobayashi, Stefan Zaefferer, André Schneider, Dierk Raabe, Georg Frommeyer
Abstract: A Fe3Al based single phase alloy was rolled at 600 °C and 400 °C and the kinetics of recrystallisation in A2 and B2 phase regions was determined in conjunction with the kinetics of the A2-B2 ordering and recovery. At 700°C and 800°C the recrystallisation kinetics depends strongly on the temperature of rolling while at 900°C only a small influence is visible. These results are attributed to the high stored energy in the sample rolled at 400 °C and its high recovery rate at 900 °C, leading to a similar level in stored energy as for the sample rolled at 600 °C in the beginning of annealing. At lower temperatures, in contrast, the difference in stored energy is conserved over longer times in the annealing process. Almost half the apparent activation energy was observed in the ordered state compared to that in the disordered state.
Authors: Shuichi Nakamura, Hotaka Homma
Abstract: Recrystallization of cold rolled {211}<011> single crystal of 3.5%Si-Fe were investigated by electron back-scattered pattern (EBSP) technique in order to clarify the formation of {h,1,1}<1/h, 1, 2> fiber in recrystallization texture of steel with high cold rolling reduction. In the cold rolled sample, there exist shearband like substructures characterized by the orientation fluctuation with single <011> axis whereas their orientations are almost kept to the original orientation {211}<011> which belongs to a-fiber (RD//<110> fiber). In the recovery stage, the orientation fluctuations are enhanced and include fluctuations with another <011> axis. That is the fluctuations in recovery stage are not characterized by rotation relationship with single <011> axis. The recrystallization texture includes {100}<012> and {411}<148> as major orientations in {h,1,1}<1/h, 1, 2> fiber. Furthermore, there exists clear orientation relationship characterized by multiple rotations with <011> axes between the recrystallization orientations and the original one. Actually, orientations characterized by rotational relationships with <211> (=[110]+[101]) axis and <111> (=[110]+[101]+[011]) were observed. These results suggest that recrystallization from a-fiber is occurred as a result of the final enhanced stage of the fluctuations characterized by multiple rotations with <011> axes.
Authors: Mark D. Nave, Kim Verbeken, Leo Kestens
Abstract: The ideal starting condition for selective growth experiments is one having a layer of randomly-oriented nuclei adjacent to a matrix with negligible orientational variation but sufficient stored energy to promote growth. In practice, cutting or deformation processes are used in an attempt to approximate these ideal conditions, but the degree to which this is achieved has not been rigorously quantified. In this work, Fe-3wt%Si single crystals were cut or deformed using six different processes. The variation in texture with distance from the cut or deformed surface was measured using electron backscatter diffraction (EBSD) in a field emission gun scanning electron microscope (FEG-SEM) in order to assess the ability of each process to create conditions suitable for selective growth experiments. While grooving with a machine tool produced the best spread of orientations at the cut surface, the suitability of this process is diminished by the presence of a differently-textured deformed layer between the cut surface and the single crystal matrix. Grinding produced a less ideal distribution of orientations at the cut surface, but the presence of these orientations in a very thin layer adjacent to the matrix makes this process preferable for preparing crystals for selective growth experiments, provided the results are corrected for the deviation in the distribution of nuclei orientations from a random distribution.
Authors: Henryk Paul, Julian H. Driver
Abstract: The crystallography of recrystallization nucleation in high purity aluminium bicrystals, with boundary planes situated parallel to the compression plane, has been characterized in detail by microtexture analyses. The experiments were carried out on samples with 2 types of bicrystal orientations composed of the stable Goss{110}<001> with an unstable cube{100}<001> or shear{100}<011> orientation. The bicrystals were cold deformed in channel-die compression up to true strains of 1.5. During recrystallization annealing, the deformation bands of the unstable orientations are the privileged sites for the formation of new grains. These nuclei were misoriented with respect to the orientations identified within the neighbouring deformed areas by α(<111>, <112> or <100>) relations. Growth of the new grains is always favoured along directions parallel to the traces of the {111} slip planes as shown in the stable and structurally homogeneous Goss {110}<001> oriented grains. The grain boundary can play a role in recrystallization similar to that of the deformation bands.
Authors: Henryk Paul, Julian H. Driver, Claire Maurice, Andrzej Piątkowski
Abstract: The recrystallization mechanisms in high purity Ag crystals with C{112}<111> initial orientation, deformed by channel-die compression, have been studied by local orientation measurements using TEM and SEM/EBSD. The microtexture analysis clearly indicates the importance of a simple relation of 25-40o (<111> or <112>) type, which is frequently observed during the early stages of recrystallization between isolated nuclei of uniform orientation and one of the as-deformed groups of components. As recrystallization proceeds, recrystallization twinning increases radically. In C-oriented silver single crystals this latter mechanism also plays a decisive role in the formation of the cube orientation.
Authors: Amel Samet-Meziou, Anne Laure Etter, Thierry Baudin, Richard Penelle
Abstract: The first steps of recovery and recrystallization in an IF-Ti steel after 40% cold rolling have been studied using the Electron Back Scattered Diffraction (EBSD), Orientation Imaging Microscopy(™) (OIM) and the Transmission Electron Microscopy (TEM). As it is well known, for low deformation amounts by cold rolling, recrystallization texture exhibits the g fiber (ND // <111>) with a reinforcement of the {111}<110> orientation. In order to understand this {111}<110> development during recrystallization, characterization of the deformed state was performed. Different microstructures were distinguished: lamellar bands for the {111}<112> grains of the g fiber and coarse elongated cells for the {111}<110> orientation that belongs to the a and g fibers. Whatever the initial dislocation structure, the recovery step seems to be characterized by coalescence and growth of existing cells in the recovered matrix. Then nucleus growth seems to occur by sub-boundary migration. The first steps of recrystallization mainly take place by continuous growth of subgrains including or not the bulging of grain boundaries.

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