scholarly journals Microstructure and Texture Evolution of Mg-Gd-Y-Zr Alloy during Reciprocating Upsetting-Extrusion

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4932
Author(s):  
Guoqin Wu ◽  
Jianmin Yu ◽  
Leichen Jia ◽  
Wenlong Xu ◽  
Beibei Dong ◽  
...  
Keyword(s):  
Dynamic Recrystallization ◽  
Basal Plane ◽  
Deformation Process ◽  
Texture Evolution ◽  
Extrusion Process ◽  
Fiber Texture ◽  
Recrystallization Process ◽  
Application Range ◽  
Continuous Dynamic Recrystallization ◽  
Cumulative Strain

Reciprocating Upsetting-Extrusion (RUE) deformation process can significantly refine the grains size and weaken the basal plane texture by applying a large cumulative strain to the alloy, which is of great significance to weaken the anisotropy of magnesium (Mg) alloys and increase the application range. In this paper, the Mg-8.27Gd-3.18Y-0.43Zr (wt %) alloy was subjected to isothermal multi-passes RUE. The microstructure and texture evolution, crystal orientation-dependent deformation mechanism of the alloy after deformation were investigated. The results clearly show that with the increase of RUE process, the grains are significantly refined through continuous dynamic recrystallization (CDRX) and discontinuous dynamic recrystallization (DDRX) mechanisms, the uniformity of the microstructure is improved, and the texture intensity is reduced. At the same time, a large number of particle phases are dynamically precipitated during the deformation process, promoting grain refinement by the particle-stimulated nucleation (PSN) mechanism. The typical [10-10] fiber texture is produced after one pass due to the basal plane of the deformed grains with a relatively high proportion is gradually parallel to the ED during extrusion process. However, the texture concentration is reduced compared with the traditional extrusion deformation, indicating that the upsetting deformation has a certain delay effect on the subsequent extrusion texture generation. After three or four passes deformation, the grain orientation is randomized due to the continuous progress of the dynamic recrystallization process.

scholarly journals Effect of Cyclic Expansion-Extrusion Process on Microstructure, Deformation and Dynamic Recrystallization Mechanisms, and Texture Evolution of AZ80 Magnesium Alloy

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Yong Xue ◽  
Shuaishuai Chen ◽  
Haijun Liu ◽  
Zhimin Zhang ◽  
Luying Ren ◽  
...  
Keyword(s):  
Magnesium Alloy ◽  
Dynamic Recrystallization ◽  
Grain Refinement ◽  
Texture Evolution ◽  
Extrusion Process ◽  
Basal Texture ◽  
Continuous Dynamic Recrystallization ◽  
Distributed Structure ◽  
Texture Intensity ◽  
Az80 Magnesium Alloy

The microstructure, deformation mechanisms, dynamic recrystallization (DRX) behavior, and texture evolution of AZ80 magnesium alloy were investigated by three-pass cyclic expansion-extrusion (CEE) tests. Optical microscopy (OM), electron back-scattered diffraction (EBSD), and X-ray diffraction (XRD) were employed to study microstructure, grain orientation, DRX mechanism, and texture evolution. The results show that the grain sizes decrease continuously with the increase of CEE pass. The grain refinement effect of the first pass is the most remarkable, and there appear a large number of twins. After three-pass CEE, a well-distributed structure with fine equiaxed grains is obtained. With the increase of CEE pass, the deformation mechanism changes from twinning to slipping and the DRX mechanism changes mainly from twinning-induced dynamic recrystallization (TDRX) to rotation dynamic recrystallization (RDRX) and then to continuous dynamic recrystallization (CDRX). The grain misorientation between the new grains and matrix grains deceases gradually, and a relatively small angle misorientation is obtained after three-pass CEE. Grain misorientations of the first two passes are attributed to TDRX and RDRX behaviors, respectively. The grain refinement changes the deformation and DRX mechanisms of CEE process, which leads the (0002) basal texture intensity first decrease and then increase suddenly. Eventually, the extremely strong basal texture is formed after three-pass CEE.

scholarly journals Microstructure and Texture Evolution of AZ31 Alloy Prepared by Cyclic Expansion Extrusion with Asymmetrical Extrusion Cavity at Different Temperatures

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3757
Author(s):  
Jie Zheng ◽  
Zhaoming Yan ◽  
Qiang Wang ◽  
Zhimin Zhang ◽  
Yong Xue
Keyword(s):  
Dynamic Recrystallization ◽  
Texture Evolution ◽  
Az31 Alloy ◽  
Continuous Dynamic Recrystallization ◽  
Initial Stage ◽  
Cumulative Strain ◽  
Coarse Grains ◽  
Different Temperatures ◽  
Continuous Dynamic ◽  
Equiaxed Grains

This work is to study the microstructure and texture evolution of AZ31 alloy prepared by cyclic expansion extrusion with an asymmetrical extrusion cavity (CEE-AEC) at different deformation temperatures. The result shows AZ31 alloy undergoes continuous dynamic recrystallization (CDRX) and discontinuous dynamic recrystallization (DDRX) during CEE-AEC processing. At the initial stage of deformation, AZ31 alloys exhibit similar bimodal microstructure of coarse deformed grains surrounded by fine DRXed grains. As the passes increase, the cumulative strain increases, and the coarse grains of all samples are almost replaced by fine equiaxed grains. The average grain sizes and the basal texture intensities of the deformed samples increase as the deformation temperature increases. In addition, due to the existence of an asymmetrical cavity, as the passes increase, the basal textures of all samples are deflected with maximum intensities increase, and even an unusual bimodal texture is formed, resulting in a soft orientation that is easy to basal slip.

scholarly journals Study of the Dynamic Recrystallization Process of the Inconel625 Alloy at a High Strain Rate

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 510 ◽  
Author(s):  
Zhi Jia ◽  
Zexi Gao ◽  
Jinjin Ji ◽  
Dexue Liu ◽  
Tingbiao Guo ◽  
...  
Keyword(s):  
Dynamic Recrystallization ◽  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Volume Fraction ◽  
Electron Backscatter Diffraction ◽  
Texture Evolution ◽  
True Strain ◽  
Recrystallization Process ◽  
Compression Process

High-temperature compression and electron backscatter diffraction (EBSD) techniques were used in a systematic investigation of the dynamic recrystallization (DRX) behavior and texture evolution of the Inconel625 alloy. The true stress–true strain curves and the constitutive equation of Inconel625 were obtained at temperatures ranging from 900 to 1200 °C and strain rates of 10, 1, 0.1, and 0.01 s−1. The adiabatic heating effect was observed during the hot compression process. At a high strain rate, as the temperature increased, the grains initially refined and then grew, and the proportion of high-angle grain boundaries increased. The volume fraction of the dynamic recrystallization increased. Most of the grains were randomly distributed and the proportion of recrystallized texture components first increased and then decreased. Complete dynamic recrystallization occurred at 1100 °C, where the recrystallized volume fraction and the random distribution ratios of grains reached a maximum. This study indicated that the dynamic recrystallization mechanism of the Inconel625 alloy at a high strain rate included continuous dynamic recrystallization with subgrain merging and rotation, and discontinuous dynamic recrystallization with bulging grain boundary induced by twinning. The latter mechanism was less dominant.

Dynamic recrystallization and texture evolution of Mg–Y–Zn alloy during hot extrusion process

2014 ◽  
Vol 92 ◽  
pp. 77-83 ◽  
Author(s):  
L.B. Tong ◽  
X. Li ◽  
D.P. Zhang ◽  
L.R. Cheng ◽  
J. Meng ◽  
...  
Keyword(s):  
Dynamic Recrystallization ◽  
Texture Evolution ◽  
Hot Extrusion ◽  
Extrusion Process ◽  
Zn Alloy

The effect of deformation degree on the microstructure of the 6060 aluminium alloy

2017 ◽  
Vol 2 (85) ◽  
pp. 80-85
Author(s):  
M. Koralnik ◽  
B. Adamczyk-Cieślak ◽  
M. Kulczyk ◽  
J. Mizera
Keyword(s):  
Plastic Deformation ◽  
Aluminium Alloy ◽  
Deformation Process ◽  
Texture Evolution ◽  
Modern Method ◽  
Extrusion Process ◽  
Hydrostatic Extrusion ◽  
Age Hardening ◽  
Future Research ◽  
Deformation Degree

Purpose: All results obtained in the present study allowed to analyse the changes in the microstructure and texture of the commercial 6060 aluminium alloy, after deformation process by severe plastic deformation. There were compare two deformation degree samples received by cumulative hydrostatic extrusion. Design/methodology/approach: The samples of the 6060 alloy were subjected to a onepass and three-passes extrusion process and next the age hardening. The microstructure changes were investigated by using transmission and scanning electron microscopy. To study the texture evolution the X-ray diffraction were made. Findings: The microscopic observations results presented the refinement of microstructure as a result of deformation process. The evolution of fibrous character of texture was observed. There were noted the disappearance of fibrous component <100> during subsequent deformation processes and generation the fibrous component <111> after high deformation degree. In addition, for each state, the presence of cubic texture component was recorded. Research limitations/implications: For the future research are planned to analyse changes in mechanical properties after hydrostatic extrusion combinate with age hardening of investigated materials. Originality/value: The paper focuses on the investigation of microstructure and texture evolution after modern method of plastic deformation.

Mechanisms of Dynamic Recrystallization in Aluminum Alloys

2014 ◽  
Vol 794-796 ◽  
pp. 784-789 ◽  
Author(s):  
Rustam Kaibyshev ◽  
Sergey Malopheyev
Keyword(s):  
Aluminum Alloys ◽  
Dynamic Recrystallization ◽  
Grain Refinement ◽  
Temperature Deformation ◽  
Recrystallization Process ◽  
Secondary Phases ◽  
Continuous Dynamic Recrystallization ◽  
3D Network ◽  
Continuous Dynamic ◽  
3D Networks

Mechanisms of dynamic recrystallization operating at severe plastic deformation in a wide temperature range are reviewed for aluminum alloys. The main mechanism of grain refinement in all aluminum alloys is continuous dynamic recrystallization (CDRX). Temperature, deformation process and distribution of secondary phases strongly affect the CDRX mechanism. Initial formation of geometrically necessary boundaries (GNBs) and a dispersion of nanoscale particles accelerate CDRX facilitating the formation of a 3D network of low-angle boundaries (LAB) followed by their gradual transformation to high-angle boundaries (HAB). At high and intermediate temperatures, 3D networks of LABs may evolve due to rearrangement of lattice dislocations by climb, and mutual intersection of GNB, respectively. At high temperatures, in aluminum alloys containing no nanoscale dispersoids the CDRX occurs through the impingement of initial boundaries forced by deformation-induced LABs. This recrystallization process is termed as geometric dynamic recrystallization (GDRX). At low temperatures, the extensive grain refinement occurs through a continuous reaction which is distinguished from CDRX by restricted rearrangement of lattice dislocation. Introduction of large misorientation may occur through the formation of 3D networks of GNBs, only.

Analysis of Large Strain Hot Torsion Textures Associated With “Continuous” Dynamic Recrystallization

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
S. M. Lim ◽  
C. Desrayaud ◽  
F. Montheillet
Keyword(s):  
Grain Boundary ◽  
Dynamic Recrystallization ◽  
Large Strain ◽  
Texture Evolution ◽  
Boundary Migration ◽  
Grain Boundary Migration ◽  
Shear Direction ◽  
Continuous Dynamic Recrystallization ◽  
Hot Torsion ◽  
Continuous Dynamic

The development of ideal orientations within the steady-state region of hot torsion flow curves of fcc and bcc metals undergoing “continuous” dynamic recrystallization is analyzed. It is well known that in fcc metals, e.g., Al deformed at 400°C and above, the experimentally observed end texture consists of the twin-symmetric B(112¯)[11¯0]/B¯(1¯1¯2)[1¯10] component, whereby the (hkl)[uvw] indices correspond to the shear plane z and the shear direction θ, respectively. In bcc iron however, only one of the self-symmetric D1(112¯)[111] and D2(1¯1¯2)[111] components dominates (the former in the case of positive shear or clockwise rotation about the r-axis, and the latter during negative shear). The tendency toward a single end orientation imposes certain limitations on grain refinement, as this would ultimately imply the coalescence of subgrains of or close to this orientation, and therefore the disappearance of existing high angle boundaries (≥15 deg). It is believed that the preference of D1 over D2, or vice versa, could be related to phenomena other than glide-induced rotations, e.g., grain boundary migration resulting from differences in work hardening rates. In this paper, the standard Taylor model is first used to predict the texture evolution in simple shear under the full-constraint rate-sensitive scheme. This is then coupled with an approach that takes into account grain boundary migration resulting from differences in dislocation densities within grains of varying orientations. The preliminary results are in agreement with experimental findings, i.e., grains with initial orientations close to D2 grow at the expense of neighboring grains during negative shear and vice versa.

Analysis on Effects of Strain Rate to Dynamic Recrystallization Process of Metals by 2-D CA Model

2013 ◽  
Vol 788 ◽  
pp. 38-42
Author(s):  
Yan He ◽  
Ming Gao ◽  
Wen Jiang Feng ◽  
Zhi Mei Zhang
Keyword(s):  
Dislocation Density ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Deformation Process ◽  
Grain Shape ◽  
Dynamic Recovery ◽  
Recrystallization Process ◽  
Strain And Strain Rate ◽  
Mean Size ◽  
Ca Model

A tow-dimensional Cellular Automaton model has been established to simulate dynamic recrystallization (DRX) process of metals. The model considers the process of dynamic recovery, dislocation density, nucleation rate and etc on DRX. The variation of dislocation density, recrystallization-grain (R-grain) shape, orientation and mean size of R-grains can be detected during the whole deformation process. The simulated results agreed well with classical theory of growth kinetics. The effects of strain and strain rate to DRX and R-grains are discussed in the end of this paper. The percentage of DRX and mean size of R-grains are related with both strain and strain rate.

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