Papers by Keyword: Recrystallization Texture

Abstract: Typical applications of ferritic stainless steels require good formability of the material that is highly dependent on the processing route. In this study, the effects of the heating rate and peak heating temperature on the texture and deep drawability (R-value) of a 78% cold rolled, stabilized 18Cr (AISI 441) ferritic stainless steel were studied. Pieces of cold rolled sheet were heated in a Gleeble 3800 simulator at the heating rates of 25 °C/s and 500 °C/s to various temperatures up to 1150 °C for 10 s holding before cooling at a rate of 35 °C/s. Microstructures were characterized and the texture of the annealed samples determined by the electron backscatter diffraction method. It was established that the high heating rate of 500 °C/s promotes the nucleation of grains with the near {111}<uvw> orientations during the early state of the recrystallization. The maximum texture intensities were found at {554}<225>. The more effective nucleation of these grains resulted in a finer grain size and an increased intensity of the gamma-fibre texture which led to enhanced R-values. At high peak temperatures, the intense grain growth took place.

Abstract: The ferritic stainless steels are materials used in several segments due to the excellent combination of mechanical properties and corrosion resistance. The mechanical properties of these alloys are strongly dependent on the microstructural characteristics and crystallography texture. The aim of this experimental study is to investigate the roles of the grain size of the hot rolled sample on the development of the microstructure, texture and formability of ferritic stainless steel. The main elements of chemical composition of the steel under investigation were 16.0 %Cr, 0.021 %C, 0.024 %N and 0.35 %Nb. Coarse and fine grains samples were cold rolled up to 90% thickness reduction and annealed at 880°C with soaking time of the 24 s. The texture measurements were performed by Electron Backscattered Diffraction (EBSD) in the longitudinal section. The formability was evaluated by the R-value and planar anisotropy (Δr) in tensile tests. The final microstructure after annealed was more homogenous for smaller initial grain size sample. This condition was favorable to develop γ-fiber, with sharpness intensity in 111121 components. The highest R-value and smallest planar anisotropy was obtained for a {111}/{001} ratio around 5.37. On the other hand, coarser initial grain size sample had showed a heterogeneous microstructure and texture, performing badly in mechanical tests (anisotropy).

Abstract: The cold-rolling texture of fcc sheet metals with medium to high stacking fault energies is known to consist of the brass {011}<211>, Cu {112}<111>, Goss {011}<100>, S {123}<634>, and cube {100}<001> components. The recrystallization (Rex) texture of cold-rolled Al, Cu and their alloy sheets is well known to be the cube texture. The 40°<111> orientation relationship between the S and cube components, which has been taken as a proof of the oriented growth theory, has made one believe that the S orientation is responsible for the cube Rex texture. The oriented growth theory is claimed to be associated with grain boundary mobility anisotropy. However, some data indicate the Cu component is linked with the cube component. There is no 40°<111> orientation relationship between the Cu and cube components. The strain-energy-release-maximization model (SERM), in which the strain energy due to dislocations is importantly taken into account, suggests that the Cu and S components in the rolling texture are linked with the cube and ~{031}<100> components in the Rex texture, respectively.

Abstract: A new rolling process, which combined asymmetric rolling with symmetric rolling, was adopted in age-hardenable 6xxx series Al-Mg-Si alloy promising as automotive body panels in order to develop favorable textures for the deep drawability after solution treatment. Symmetric cold rolling at high reduction and subsequent asymmetric warm rolling at low reduction for AA6022 sheets led to the formation of “TD-rotated β-fiber texture” including moderate {111}<uvw>-oriented components, resulting in noticeable evolution of {111}<110> recrystallization texture during the solution treatment at a high temperature. The results of texture analysis and microstructural observation suggested that the low stored energy after asymmetric warm rolling, the high fraction of high angle boundaries with neighboring deformed matrices and the approximate 40° <111> orientation relationship with deformed matrices would strongly affect the evolution of {111}<110> recrystallization texture.

Abstract: T.M.C.P.(Thermo Mechanical Control Processing) has been widely used to improveplastic formability in steel strips. We have produced interstitial free steel(IF steel) strips and ferriticstainless-steel strips through T.M.C.P. rolling method. Optimizing conditions of hot rolling, hotrolled annealing, cold rolling and cold rolled annealing, we developed texture prediction model. Wecan predict rolling texture accurately using the conventional Taylor model. Moreover, we preciselypredict recrystallization texture classifying the total number of microscopic􀀁 slips which arecalculated using the Taylor model. We consider that these calculated results provednucleation-oriented model and two types of recrystallization and grain growth mechanisms exit inour studies. One mechanism is that grains which had the small total number of microscopic slips arepreferred orientation for the hot rolled and annealed ferritic stainless-steel strip. The othermechanism is that grains which had the high total number of microscopic slips are preferredorientation for the cold rolled and annealed IF steel strip.

Abstract: The effects of a 2 T pulsed magnetic field primary annealing process on microstructure evolution and grain boundary characteristics in two-stage cold-rolled silicon steel were examined. Pulsed magnetic annealing increased grain size through the application of relatively smaller intensity of magnetic fields (2 T), compared to steady magnetic annealing. The effect of increasing grain size may be attributed to the magnetic acceleration effect of boundary motion under magnetic pulse conditions. Pulsed magnetic annealing may serve to enhance the relative intensity of the {111} component and decrease the frequency of low-angle misorientations. Repeated magnetostriction induced by pulsed magnetic field applications may accelerate overall dislocation motion. These findings suggest that pulsed magnetic fields require relatively lower intensities than steady magnetic fields to achieve superior results, providing a potentially viable alternative for industrial annealing processes for electrical steels.

Abstract: The silicon steel was rolled to 95% reduction at 20°C, 400°C and 600°C, and subsequently annealed at different temperatures to obtain complete recrystallization microstructure without appreciable grain growth. The effects of rolling temperature on through-thickness deformation and recrystallization textures were investigated by ODF analysis. The deformation textures are all composed of α- and γ-fiber, whereas α-fiber and {111}﹤110﹥ decrease and {111}﹤112﹥ increases with the increasing rolling temperature. Through-thickness recrystallization texture varied significantly, a strong partial γ-fiber spreading from {111}﹤112﹥ or {554}﹤225﹥ to {111}﹤134﹥ and {114}﹤481﹥ are developed in steel sheet rolled at 20°C and 400°C, while a dominated η-fiber peaked at {310}﹤001﹥ is formed between surface and quarter thickness in steel sheet rolled at 600°C. The different recrystallization textures can be ascribed to the profuse shear band at 600°C compared with the microstructures at 20°C and 400°C.

Abstract: The texture of rolled sheets is known to vary with depth from the surface to the center due to inhomogeneous deformation, which can be caused by a characteristic deformation zone geometry and friction between materials and rolls during rolling. In order to study the deformation and recrystallization (Rex) textures of the surface layers of Al and Cu sheets cold rolled without lubrication, 5 Al sheets were stacked and rolled by 88% and 4 Cu sheets were stacked and rolled by 93% in 4 passes at room temperature. The surface layers separated from the rolled sheets were annealed for 1 h at 500 °C for Al and at 550 °C for Cu. The deformation textures of the surface layers were characterized by different shear textures, which gave rise to very different Rex textures.

Abstract: The recrystallization behavior of the cold rolled 3%Si nonoriented electrical steel at different temperatures is investigated by OIM(Orientation Imaging Microscopy). The results show that the recrystallization process and texture of 3%Si nonoriented electrical steel at different temperatures are determinated by different recrystallization mechanisms. At low annealing temperatures, the formation of recrystallization texture in this specimen can be explained by the mechanism of oriented nucleation theory, but at higher annealing temperatures, the formation of recrystallization texture in this specimen can be explained by the mechanism of oriented growth theory, the twin nucleation mechanism may penetrate the whole recrystallization process.

Abstract: The 4.2wt.%Si non-oriented electrical steel thin sheets with the thickness of 0.30mm were produced by the conventional procedure including hot rolling, cold rolling and annealing. The recrystallization texture was analyzed with emphasis on the effect of normalizing annealing. The results show that the  fiber with peak at {111} is weaker and η fiber is stronger in the sheets with normalizing annealing than those without normalizing annealing, either under the cold rolled reduction of 77% or 86%. Effects of normalizing annealing on the recrystallization texture can be explained in terms of the characteristic of the shear bands formed during cold rolling process.