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.

A STUDY OF DYNAMIC RECRYSTALLIZATION IN TA15 TITANIUM ALLOY DURING HOT DEFORMATION BY CELLULAR AUTOMATA MODEL

2009 ◽  
Vol 23 (06n07) ◽  
pp. 934-939 ◽  
Author(s):  
DONG HE ◽  
JING CHUAN ZHU ◽  
YANG WANG ◽  
YONG LIU
Keyword(s):  
Titanium Alloy ◽  
Flow Stress ◽  
Dislocation Density ◽  
Cellular Automata ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Hot Deformation ◽  
Temperature Filed ◽  
Ca Model ◽  
Grain Growth Model

The dynamic recrystallization (DRX) of TA 15 ( Ti -6 Al -2 Zr -1 Mo -1 V ) titanium alloy during the hot deformation process was studied by the Cellular Automata (CA) model which is base on the dislocation density theory. To build the CA model, the dislocation density model, dynamic recovery model, nucleation model and grain growth model were introduced and developed. The influences of strain rate on the microstructure evolution and flow stress character were investigated which shows that high strain rate leads to later DRX appearance, high flow stress peak value, small mean size of recrystallizing grains( R -grains) and low DRX percentage, but they have the similar Avrami curve. The characteristic of DRX process in a modeling non-uniform temperature filed (NTF) has been studied. All the simulation results show good agreement with the pioneer's work and experimental results.

Damage evolution and recrystallization enhancement of frozen loess

2017 ◽  
Vol 27 (8) ◽  
pp. 1131-1155 ◽  
Author(s):  
Zhiwei Zhou ◽  
Wei Ma ◽  
Shujuan Zhang ◽  
Cong Cai ◽  
Yanhu Mu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Damage Evolution ◽  
Deformation Process ◽  
Triaxial Compression ◽  
Confining Pressure ◽  
Recrystallization Process ◽  
Frozen Soils ◽  
Time Deformation ◽  
Pressure Melting

A series of multistage triaxial compression, creep, and stress relaxation tests were conducted on frozen loess at the temperature of −6℃ in order to study the damage evolution and recrystallization enhancement of mechanical properties during deformation process. The effect of strain rate, confining pressure, and hydrostatic stress history in the degradation laws of mechanical properties is investigated further. The strain rate has a significant influence on the stress–strain curve which dominates the evolution trend of mechanical properties. The mechanical behaviors (strength, stiffness, and viscosity) of frozen loess all exhibit evident response for the consolidation and pressure melting phenomenon caused by the confining pressure. The multistage loading tests under different hydrostatic stresses are capable of differentiating the development characteristics of mechanical properties during axial loading and hydrostatic compression process, respectively. The testing results indicated that the recrystallization of the ice particle in the frozen soils is an important microscopic factor for enhancement behaviors of mechanical parameters during the deformation process. This strengthening degree of mechanical properties is determined by temperature, duration time, deformation degree, and stress state during the recrystallization process. The phase transformation led by pressure melting and ice recrystallization is a nonnegligible changing pattern of frozen soils microstructure, which has apparent role in the damage evolution of mechanical properties.

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 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.

Cellular Automaton Simulation and Experimental Observation of the Dynamic Recrystallization of Titanium Alloy TC11 with Varied Strain Rates

2012 ◽  
Vol 476-478 ◽  
pp. 71-74
Author(s):  
Zhi Fu Yang ◽  
Qing Yuan Meng ◽  
Yu Hang Jing
Keyword(s):  
Titanium Alloy ◽  
Dislocation Density ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Cellular Automaton ◽  
Experimental Observation ◽  
Hot Working ◽  
Strain Rates ◽  
Working Process ◽  
Loading Sequence

During the metal hot working process, the dislocation density will vary with strain and strain rate, and the variation of the dislocation density will affect the grain evolution subsequently. The cellular automaton (CA) method is an effective technique used to simulate the grain evolution of materials. In this work, a dynamic recrystallization (DRX) model of titanium alloy TC11 under varied strain rates was established by the use of cellular automaton method and verified by experimental observation. Two types of loading processes called “begin fast and then slowly” and “begin slowly and then fast” were simulated to investigate the titanium alloy TC11 grain evolution processes during hot working. The simulation results are in good coincidence with experimental data. Both cellular automaton simulation and experimental results show that the flow stresses and DRX transformation percentage during hot working process of the TC11 alloy are closely related not only to the strain rate but also to the loading sequence. Compared to the “begin slowly and then fast” loading sequence, the flow stress with the “begin fast and then slowly” loading sequence is relatively smaller under the same strain rates, and the DRX transformation percentage is relatively larger.

Recrystallization of 304SS during and after High Strain Rate Deformation

2013 ◽  
Vol 753 ◽  
pp. 403-406
Author(s):  
Adam S. Taylor ◽  
Peter D. Hodgson
Keyword(s):  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Austenitic Stainless Steels ◽  
Avrami Equation ◽  
Recrystallization Process ◽  
Hollomon Parameter ◽  
Softening Mechanism ◽  
Recrystallization Kinetics ◽  
Kinetics Of ◽  
Shape Changes

During the hot working of austenitic stainless steels the shape of the flow curve is strongly influenced by the strain rate. Low strain rate deformation results in flow curves typical of dynamic recrystallization (DRX) but as the strain rate increases the shape changes to a ‘flat-top’ curve. This has traditionally been thought to indicate no DRX is taking place and that dynamic recovery (DRV) is the only operating softening mechanism. Examining the work-hardening behaviour and corresponding deformation microstructures showed this is not the case for austenitic stainless steel, as clear evidence of dynamic recrystallization process can be seen. The post-deformation recrystallization kinetics can be modelled using a standard Avrami equation with an Avrami exponent, n, of 1.15. With an increasing value of the Zener-Hollomon parameter it was found that the kinetics of recrystallization become less strain rate sensitive until at the highest values (highest strain rates/lowest temperatures) the recrystallization kinetics become strain rate insensitive.

Modeling of Dynamic Recrystallization Process in AZ31 Magnesium Alloy Using Cellular Automaton Method

2015 ◽  
Vol 833 ◽  
pp. 19-22
Author(s):  
Xiao Hu Deng ◽  
Dong Ying Ju ◽  
Xiao Dong Hu ◽  
Hong Yang Zhao
Keyword(s):  
Dynamic Recrystallization ◽  
Grain Growth ◽  
Grain Morphology ◽  
Mg Alloy ◽  
Recrystallization Process ◽  
Az31 Mg Alloy ◽  
Dynamic Recrystallization Behavior ◽  
Ca Model ◽  
Grain Growth Model ◽  
Experimental Findings

A modified 2-D CA model has been developed to simulate dynamic recrystallization behavior of Magnesium (Mg) alloy during hot deformation processing. Based on the fact that Mg has an HCP crystal structure with six-fold symmetry, the model employs the hexagonal CA lattice. The initial microstructure with prescribed grain size was generated by a normal grain growth algorithm. The DRX model consists of dislocation density evolution model, DRX nucleation model and recrystallization grain growth model. DRX grain morphology and size, flow curve were simulated by the present model. The calculated results were compared with the available experimental findings in AZ31 Mg alloy, the predictions show very good agreement with the experimental results.

Effect of Deformation Conditions on Dynamic Recrystallization of As-Cast GH625 Alloy

2015 ◽  
Vol 816 ◽  
pp. 620-627
Author(s):  
Hao Yu Wang ◽  
Jian Xin Dong ◽  
Mai Cang Zhang ◽  
Lei Zheng ◽  
Zhi Hao Yao ◽  
...  
Keyword(s):  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Process Design ◽  
Deformation Process ◽  
Strain Rates ◽  
Recrystallization Behavior ◽  
Compression Tests ◽  
Volume Percent ◽  
Dynamic Recrystallization Behavior ◽  
Continuous Recrystallization

High temperature compression tests at a deformation temperature range of 1273K~1473K with various strain rates of 0.01s-1~0.1s-1 on as-cast GH625 alloy were carried out, aiming at the current research status that the deformation process of cogging and the recrystallization behavior of ingot are still in the study. The results indicated that the recrystallization nuclei of ingot formed not only along the original grain boundaries, but also in the interdendrite. Dynamic recrystallization volume percent increased with the increase of temperature and the decrease of strain rate. When the temperature was high and strain rate was low, the dynamic recrystallization behavior of as-cast GH625 alloy was dominated by discontinuous recrystallization. However, when the temperature was low and strain rate was high, continuous recrystallization also existed. These results can provide some reliable experimental support for the cogging process design.

scholarly journals Simulation of Dynamic Recrystallization Behavior under Hot Isothermal Compressions for as-extruded 3Cr20Ni10W2 Heat-Resistant Alloy by Cellular Automaton Model

2018 ◽  
Vol 37 (7) ◽  
pp. 635-647 ◽  
Author(s):  
Le Li ◽  
Li-yong Wang
Keyword(s):  
Grain Size ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Cellular Automaton ◽  
Deformation Temperature ◽  
Experimental Result ◽  
Recrystallization Behavior ◽  
Dynamic Recrystallization Behavior ◽  
Ca Model ◽  
Recrystallized Grain Size

AbstractIn order to study dynamic recrystallization behavior of the as-extruded 3Cr20Ni10W2 under isothermal compression conditions, a cellular automaton (CA) model was applied to simulate hot compression. Analysis on the strain–stress curves indicates that dynamic recrystallization is the main softening mechanism for the 3Cr20Ni10W2 when the deformation occurred in the temperature range of 1203–1303 K with an interval of 50 K and strain rate range of 0.01–10 s−1. The deformation temperature and strain rate have a significant influence on the dynamically recrystallized grain size. Subsequently, a CA model is established to simulate the dynamic recrystallization behaviors of the studied alloy. The simulated results show that the mean grain size increases with the increased deformation temperature and decreases with the increased strain rate, which is consistent with the experimental result. In addition, the average absolute relative error, which is 13.14%, indicates that the process of the dynamic recrystallization and the dynamically recrystallized grain size can be well predicted by the present CA model.

scholarly journals Microstructure Evolution of Allotropic Materials during Thermomechanical Processing

2012 ◽  
Vol 710 ◽  
pp. 93-100 ◽  
Author(s):  
Cecilia Poletti ◽  
Fernando Warchomicka ◽  
Martina Dikovits ◽  
Simon Großeiber
Keyword(s):  
Phase Transformation ◽  
Dynamic Recrystallization ◽  
Constitutive Equations ◽  
Power Dissipation ◽  
Hot Deformation ◽  
Power Efficiency ◽  
Dynamic Recovery ◽  
Carbon Steels ◽  
Processing Maps ◽  
Strain And Strain Rate

The microstructure developed during hot deformation is the result of deformation mechanisms such as dynamic recovery and dynamic recrystallization. Hot deformation can also result in damage and flow localisation, especially in multiphase metal based materials. Several models have been proposed to correlate the parameters of the deformation process (temperature, strain and strain rate) with the flow behaviour such as the processing maps. They were developed based on the dynamic materials model (DMM) and later a modified DMM introduced some changes in the calculation of the processing maps. The correlation of the relevant microstructural changes with thermodynamic parameters are tested and discussed. The data was obtained by using the Gleeble simulator with in situ quenching facilities. Microstructural studies related to the hot deformation of metals were carried out based on alpha-beta and near beta titanium alloys and on low carbon steels. The results are correlated with the efficiency of power dissipation, and the constitutive equations. In diffusion controlled processes such as dynamic recovery, dynamic recrystallization, phase transformation and pore coarsening are related to high power efficiency, and to low n exponent. The efficiency of power dissipation is more sensitive to the deformation parameters than the constitutive equations for materials with phase transformation.

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