scholarly journals Dynamic recrystallization behavior of 6082 aluminum alloy during hot deformation

2021 ◽  
Vol 13 (9) ◽  
pp. 168781402110461
Author(s):  
Hai-bo Lin
Keyword(s):  
Aluminum Alloy ◽  
Grain Boundary ◽  
Dynamic Recrystallization ◽  
Hot Deformation ◽  
Critical Strain ◽  
Boundary Migration ◽  
Large Angle ◽  
Strain Curve ◽  
Subgrain Structure ◽  
6082 Aluminum Alloy

The dynamic recrystallization behaviors of 6082 aluminum alloy in the temperature range of 623–773 K and strain rate range of 0.01–5 s−1 were studied by electron back scattered diffraction (EBSD) and transmission electron microscopy (TEM). According to the experimental results, dynamic recrystallization occurs during hot deformation of 6082 aluminum alloy, although the true stress-strain curve has no obvious single peak characteristic, and the degree of dynamic recrystallization is closely related to the Z parameter. Hot compression with lnZ = 24.9014 (723 K, 0.1 s−1) gives rise to the highest recrystallization fraction of 38.6%. The initial critical strain of dynamic recrystallization was determined by the work hardening rate. The quantitative relationship between the critical strain and Z parameters was established: [Formula: see text]. Based on the EBSD analysis and measurement results, dynamic recrystallization kinetics models of 6082 aluminum alloy during hot deformation were deduced. Microstructure analysis showed that the subgrain structure formed in the original grain is coarsened by grain boundary migration, and the orientation difference increases continuously until a large-angle grain boundary forms, resulting in dynamic recrystallization of grains. The likely mechanism is continuous dynamic recrystallization.

scholarly journals Hot Deformation Behavior and Microstructure Evolution of 6063 Aluminum Alloy Modified by Rare Earth Y and Al-Ti-B Master Alloy

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4244 ◽  
Author(s):  
Wanwu Ding ◽  
Xiaoxiong Liu ◽  
Xiaoyan Zhao ◽  
Taili Chen ◽  
Haixia Zhang ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Rare Earth ◽  
Dynamic Recrystallization ◽  
Master Alloy ◽  
Hot Deformation ◽  
True Strain ◽  
Constitutive Models ◽  
Hot Workability ◽  
Continuous Dynamic Recrystallization ◽  
6063 Aluminum Alloy

The hot deformation behaviors of the new 6063 aluminum alloy modified by rare earth Y and Al-Ti-B master alloy were studied through isothermal hot compression experiments on the Gleeble-3800 thermal simulator. By characterizing the flow curves, constitutive models, hot processing maps, and microstructures, we can see from the true stress–true strain curves that the flow stress decreases with the increase of deformation temperature and the decrease of strain rate. Through the calculation of the constitutive equation, we derived that the activation energy of the new composite modified 6063 aluminum alloy is 224.570 KJ/mol. we roughly obtained its excellent hot processing range of temperatures between 470–540 °C and the strain rates of 0.01–0.1 s−1. The verification of the deformed microstructure shows that with the decrease of lnZ, the grain boundary changes from a low-angle one to a high-angle one and the dynamic recrystallization is dominated by geometric dynamic recrystallization and continuous dynamic recrystallization. Analysis of typical samples at 480 °C/0.01 s−1 shows that the addition of rare earth Y mainly helps form Al3Y5 and AlFeSiY phases, thus making the alloy have the performance of high-temperature recrystallization, which is beneficial to the hot workability of the alloy.

scholarly journals Microstructural Evidence for Grain Boundary Migration and Dynamic Recrystallization in Experimentally Deformed Forsterite Aggregates

Minerals ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 17
Author(s):  
Caroline Bollinger ◽  
Billy Nzogang ◽  
Alexandre Mussi ◽  
Jérémie Bouquerel ◽  
Dmitri Molodov ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Dynamic Recrystallization ◽  
Grain Boundaries ◽  
Driving Forces ◽  
Electron Backscatter Diffraction ◽  
Boundary Migration ◽  
Large Strains ◽  
Grain Boundary Migration ◽  
Mapping Techniques ◽  
Von Mises

Plastic deformation of peridotites in the mantle involves large strains. Orthorhombic olivine does not have enough slip systems to satisfy the von Mises criterion, leading to strong hardening when polycrystals are deformed at rather low temperatures (i.e., below 1200 °C). In this study, we focused on the recovery mechanisms involving grain boundaries and recrystallization. We investigated forsterite samples deformed at large strains at 1100 °C. The deformed microstructures were characterized by transmission electron microscopy using orientation mapping techniques (ACOM-TEM). With this technique, we increased the spatial resolution of characterization compared to standard electron backscatter diffraction (EBSD) maps to further decipher the microstructures at nanoscale. After a plastic strain of 25%, we found pervasive evidence for serrated grain and subgrain boundaries. We interpreted these microstructural features as evidence of occurrences of grain boundary migration mechanisms. Evaluating the driving forces for grain/subgrain boundary motion, we found that the surface tension driving forces were often greater than the strain energy driving force. At larger strains (40%), we found pervasive evidence for discontinuous dynamic recrystallization (dDRX), with nucleation of new grains at grain boundaries. The observations reveal that subgrain migration and grain boundary bulging contribute to the nucleation of new grains. These mechanisms are probably critical to allow peridotitic rocks to achieve large strains under a steady-state regime in the lithospheric mantle.

Effect of β Annealing and near β Zone Hot Deformation on the Microstructure and Texture of TC18 Alloy

2016 ◽  
Vol 849 ◽  
pp. 226-231
Author(s):  
Yi Min Cui ◽  
Wei Wei Zheng ◽  
Feng Zhang ◽  
Ai Xue Sha
Keyword(s):  
Grain Boundary ◽  
Dynamic Recrystallization ◽  
Small Angle ◽  
Hot Deformation ◽  
Static Recrystallization ◽  
Dynamic Recovery ◽  
Fiber Texture ◽  
Dual Phase ◽  
Phase Zone ◽  
Β Phase

Forged TC18 alloy billets with strong <100> texture were selected to investigate the effects of β annealing and near β zone hot deformation on the microstructure and texture by means of optical microscopy, XRD and EBSD techniques. The results showed that the original <100> fiber texture can’t be eliminated through β annealing although completed static recrystallization happened during annealing. After deforming in near β phase zone, the microstructures were composed of elongated β grains. A lot of small angle boundaries were observed near the original β grain boundaries, indicating that dynamic recovery controlled the deformation. Dynamic recrystallization grains can only be seen at the original β grain boundary at the strain of 50%. <100>//TD and <111>//TD texture were generated during the near β zone hot deformation. Annealing at dual phase zone after hot deformation can effectively reduce the proportion of grains with <111> orientation, but the <100>//TD texture still existed.

scholarly journals Hot Deformation Behavior of Cu–Sn–La Polycrystalline Alloy Prepared by Upcasting

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3739
Author(s):  
Siming Hua ◽  
Pingze Zhang ◽  
Zili Liu ◽  
Lin Yang
Keyword(s):  
Dynamic Recrystallization ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
Testing Machine ◽  
Shear Bands ◽  
Strain Curve ◽  
Extrusion Process ◽  
Hot Deformation Behavior ◽  
Polycrystalline Alloy ◽  
Promising Application

In this study, the hot deformation of a Cu–0.55Sn–0.08La (wt.%) alloy was studied using a Gleeble-3180 testing machine at deformation temperatures of 400–700 °C and various strain rates. The stress–strain curve showed that the hot deformation behavior of the Cu–0.55Sn–0.08La (wt.%) alloy was significantly affected by work hardening, dynamic recovery, and dynamic recrystallization. The activation energy Q was 261.649 kJ·mol−1 and hot compression constitutive equation was determined as  ε˙=[sinh(0.00651σ)]10.2378·exp(33.6656−261.649RT). The microstructural evolution of the alloy during deformation at 400 °C revealed the presence of both slip and shear bands in the grains. At 700 °C, dynamic recrystallization grains were observed, but recrystallization was incomplete. In summary, these results provide the theoretical basis for the continuous extrusion process of alloys with promising application prospects in the future.

Critical Condition of Dynamic Recrystallization of Mid-Ti Contained in Q345B

2014 ◽  
Vol 1030-1032 ◽  
pp. 39-42
Author(s):  
Qiang Xiao ◽  
Jun Hong Li ◽  
Xu Luo ◽  
Xu Jiang Liu
Keyword(s):  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Deformation Temperature ◽  
Critical Strain ◽  
Simulation Experiment ◽  
Strain Curve ◽  
True Stress ◽  
Stress Strain Curve ◽  
The One ◽  
Thermal Simulation Experiment

the one pass compression test of Mid-Ti Contained in Q345B was achieved by using the Gleeble-1500 thermal simulation experiment machine. The true stress-strain curve was studied under the deformation temperature was between 1000 to 1150°C and the strain rate was from 0.01 to 0.3 s-1. And then, based on Sellars model, the function relationships between critical strain (εc), strain rate (ε) and deformation temperature (T) of dynamic recrystallization of the Mid-Ti Contained in Q345B were reached:εc=2.588×10-3Z0.12,Z=εexp (439583/8.314T).

scholarly journals Influence of Hot Deformation and Precipitates on the Recrystallization of Nb-V-Ti Free-Cutting Steel

Metals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1587
Author(s):  
Yang Yang ◽  
Xian-Ming Zhao ◽  
Chun-Yu Dong ◽  
Xiao-Yu Zhao
Keyword(s):  
Grain Boundary ◽  
High Strain Rate ◽  
Strain Rate ◽  
Hot Deformation ◽  
High Strain ◽  
Boundary Migration ◽  
Great Influence ◽  
Material Model ◽  
Dislocation Motion ◽  
Cutting Steel

Nb, V, and Ti were added to free-cutting steel to improve its mechanical properties by means of precipitation strengthening and fine grain strengthening. The process parameters during the hot deformation of Nb-V-Ti free-cutting steel were studied at strain rates of 0.01–10 s−1 and temperatures of 850–1250 °C. The isothermal compression test results showed that the temperature rise at low deformation temperature and high strain rate has a great influence on the softening of the steel. The processing maps at strains of 0.3–0.6 were established based on a dynamic material model (DMM). When the strain was 0.6, the optimum hot-working window was at a temperature in the range of 1150–1250 °C and at a strain rate in the range of 0.01–0.1 s−1. The instable regions were mainly located at low temperature and high strain rate. The instable characteristics included the mixed grains around the MnS phase, flow localization, and intense deformation. In general, the existence of MnS leads to a decrease in the toughness of the steel. The MnS phase was easy to be broken when the compression tested at a lower temperature, e.g., 850 °C and at a higher strain rate, e.g., 10 s−1; its morphology changed from a long-rod shape to a discontinuous shape, and then, to a dot-like shape with the decrease in temperature from 1250 to 850 °C and the increase in strain rate from 0.01 to 10 s−1. The nucleation mechanism of this steel was grain boundary bulging. The size of fine (Nb,Ti) (C,N) precipitates is less than 10 nm, inhibiting austenite recrystallization and leading to austenite strengthening during hot deformation at 850 °C. Moreover, the dislocation motion and grain boundary migration were greatly inhibited by the Ti-rich(C,N) and MnS throughout the entire hot deformation process.

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