Papers by Keyword: Recrystallization Texture

Abstract: The evolution of recrystallization texture in the non-orientation electrical steel containing copper during annealing at 950°C for 3～180s have been studied by EBSD (Electron Backscatter Diffraction) measurements. Goss grains({011}) are nucleated within shear bands in deformed {111} and{111} grains. {111} grains nucleate in deformed {111} grains and new{111} grains nucleate in deformed {111}grains. {111} grains have an evident advantage both in number and growth rate over α grains, thus the controlling of annealing time can contribute to the increase of {011} texture.

Abstract: The annealing behavior of cold rolled Type 430 ferritic stainless steel is the subject of this paper. The steel was cold rolled 79%, then heated at 6 °C/s to the soaking temperature of 841 °C, which is just below the Ae₁ temperature. During heating, specimens were quenched from selected temperatures between 650 and 841 °C and after various times at 841 °C. These quenched samples underwent metallographic examination and micro-hardness determination. The results indicated that under the prevailing experimental conditions, the hardness appeared to correlate strongly with the extent of recrystallization. The kinetics of recrystallization appeared to originate in the cold worked state, where three kinds of grain were found: (i) smooth elongated, featureless of α-fiber orientation {001}<100>; (ii) irregular fishbone grains of the γ-fiber orientations {111}<112> plus {111}<110>; and (iii) twisted grains of the η-fiber orientation {001}<100>. It was found that the twisted grains of the η-fiber were the first to recrystallize, with the fishbone grains of the γ-fiber second, and the smooth elongated, featureless grains of the α-fiber last. It was found that the grains of the α-fiber orientation {001}<100> and the η-fiber orientation {001}<100> were replaced with grains of the γ-fiber orientations as recrystallization progressed. These results are discussed in terms of recrystallization and texture development.

Abstract: Deformation structures and annealing behaviour have been analysed in the centre layer of two AA1050 samples cold-rolled to von Mises strains of 3.6 and 6.4. During annealing at 270-300°C structural coarsening and discontinuous recrystallization occurred in both samples. In the coarsened microstructure, the fraction of high angle boundaries was slightly lower than that in the as-rolled conditions. Recrystallization textures of both samples contained significant fractions of the rolling texture components. The fraction of the retained rolling texture was however greater in the strain-6.4 sample. The {001}<310> and {110}<566> components were also pronounced in this sample. The size of recrystallized grains having orientations of the rolling texture was considerably smaller than the size of grains having other crystallographic orientations. This may be attributed to orientation pinning that hinders growth of grains with orientations of the rolling texture.

Abstract: In order to develop favorable textures for deep drawing of Al-Mg-Si and Mg-Al-Zn alloys that are promising as automotive body panels, we have adopted the symmetric/asymmetric combination rolling (SACR) process consisting of conventional symmetric rolling and subsequent asymmetric rolling at relatively low reduction. The combination of symmetric cold rolling and asymmetric warm rolling for AA6022 sheets leads to the formation of “TD-rotated β-fiber texture”, resulting in the evolution of {111} recrystallization texture after solution treatment at a high temperature. The SACR processed and solution-treated sheets show a high average r-value with small in-plane anisotropy, and consequently the limiting drawing ratio increases significantly, compared to that of the cold-rolled and solution-treated sheets. In the case of AZ31 magnesium alloy, the SACR process by hot rolling causes the formation of a unique texture, which shows two (0001) poles with tilt angles of 0 and −40 degrees from the normal direction (ND) toward the rolling direction (RD). In addition, subsequent annealing weakens intensity of the double-peak texture, so that the drawability is greatly improved in comparison with that of the conventional warm-rolled sheets with a strong basal texture. At the same time, yield strength decreases to some extent, but the SACR processed and annealed sheets exhibit a good balance of strength and formability due to a mixed texture with basal and tilt components.

Abstract: The effect of temperature on the recrystallization texture and microstructure of non-oriented silicon steel under asymmetrically rolling condition was quantatively studied using X-ray diffraction technology. The results show that the texture component accumulates around {111}<112> when annealed at 800°C. Texture intensity is high and grain size is uniformly distributed between 50μm and 100μm with best magnetism. When annealed at 850°C and 900°C, texture component is scattered and the grain size is also bigger. However, for the annealing at 750°C, the texture component is similar to cold rolled process. The grain size is small and non-uniform, which is unfavorable to magnetism. The difference of forces along the fast and slow side of the roller results in different deformation texture and further affects the intensity of recrystallization texture along the two sides of the roller.

Abstract: In this work the nucleation of the Cube recrystallised grains in AA6111 was investigated. The alloys were cold rolled to 85% and then annealed at different temperatures in an air circulation furnace. X-ray diffraction was used to obtain global textures and for specific area of interest, Electron-Back Scattered Pattern (EBSP) was used. In order to observe the microstructures after rolling and partially annealing, Scanning Electron Microscopy (SEM) was used. It was found that the recrystallisation textures are strongly related to the annealing temperature. The recrystallisation texture after low temperature annealing gives a strong retained rolling texture and at high temperature, a fairly random texture with weak Cube and rotated Cube components. The difference in the volume fraction of Cube with different alloys and annealing temperature are related to the deformation microstructures. Cube bands are observed to be deformation bands on the rolling plane. During annealing, precipitates are formed on the deformation band boundaries and Cube nuclei which are formed in the deformation Cube band are restricted to growth due to the precipitates.

Abstract: Effects of electric field annealing on recrystallization texture and average plastic strain ratio (r value) of IF steel sheet were studied by mean of X ray diffraction ODF analysis and the tensile test. Specimens of 75% cold-rolled IF steel sheet were annealed at 850flC for 25min,with and without electric field annealing respectively. Results show that the electric field annealing does not change the type of recrystallization texture and its formation mechanism in IF deep-drawing steel sheet, but improves the formation and development of recrystallization i-fiber texture, enhances the intensity of i-fiber texture, and retards the formation and development of c-fiber texture. Comparing with the conventional annealing, electric field annealing improves the average plastic strain ratio (r value). Possible reasons for the intensification of recrystallization i-fiber texture with the electric field applied may attribute to the reduction of stored energy, thus hindering the formation of other orientated nuclei and enhancing the nucleating ratio of i-oriented nuclei. And the intensification of recrystallization i-fiber texture was considered as the main reason for the enhancement of the plastic strain ratio (r value) in IF steel sheet.

Abstract: The microstructural and mechanical properties of an ultra-clean low carbon steel sheet with 0.035% Cr have been evaluated. The isothermal recrystallization kinetics at 800 oC is analyzed by using the Kolomogorov-Johnson-Mehl-Avrami (KJMA) equation. The obtained results indicate that Cr retards the recrystallization kinetics owing to the presence of fine particles of chromium carbides. The annealing process produces a fully recrystallized microstructure. The main texture components in the specimens are: {111}<112>, {112}<110> and {111}<110>. These are related with the Lankford value and the elongation. The obtained results suggest that the formability of this steel is excellent.

Abstract: In warm rolled steels, the intensity of the <111>//ND annealing texture, which favours formability, has been related to the formation of shear bands during rolling. Coarse hot band grain sizes (HBGS’s) facilitate flow localization, the mechanism associated with the formation of shear bands.In this work, the effect of grain size after hot rolling was studied in a low carbon steel containing small additions of Cr and Mn. The formation of shear bands and their subsequent influence on the normal anisotropy rm and planar anisotropy Dr in the annealed steels were of particular interest. Two HBGS’s (18 and 30mm) were employed and the specimens were warm rolled to reductions of 65 and 80% at various temperatures between 640 and 700°C. The results show that the frequency of shear banding is slightly lower for the smaller grain size. The normal anisotropy was not affected by the HBGS; by contrast, much lower Dr values were associated with the finer grained steel.

Abstract: Texture transition in silver introduced by the addition of 10 at% Pd alloying element was analyzed in this study. Experimental results show that the dependence of rolling texture on rolling reduction in thickness rather than on rolling temperature has been mostly detected, and the recrystallization texture transition process in pure silver is so strongly influenced by the addition of alloying element palladium that the final stable state of recrystallization texture has been changed from Brass {011}<211> orientation to Copper {112}<111> orientation. The single cube {001}<100> recrystallization texture in warm rolled silver, Brass {011}<211> recrystallization texture in room-temperature rolled silver, and Copper {112}<111> recrystallization texture in room-temperature rolled or warm rolled Ag-10 at% Pd alloy have been successfully developed for the fabrication of metallic substrates suitable for high-temperature superconducting tapes.