Dynamic Recrystallization and Microstructure Evolution in AZ31 Magnesium Alloy during Thermomechanical Processing

2005 ◽  
Vol 488-489 ◽  
pp. 215-218 ◽  
Author(s):  
Guang Jie Huang ◽  
Ling Yun Wang ◽  
Guang Sheng Huang ◽  
Fu Sheng Pan
Keyword(s):  
Flow Stress ◽  
Magnesium Alloy ◽  
Dynamic Recrystallization ◽  
High Temperatures ◽  
Critical Strain ◽  
Thermomechanical Processing ◽  
Stable State ◽  
Az31 Magnesium Alloy ◽  
Strain Rates ◽  
Peak Strain

The deformation behavior of AZ31 magnesium alloy has been investigated by isothermal compression at temperatures between 573-723K and at constant strain rates ranging from 10-3 -1s-1. It is shown that the form of flow stress curves is very sensitive to temperature and strain rate. In the experimental domain studied, the flow stresses are modeled using a power law with an average activation energy of 145.16 kJ/mol, and dynamic recrystallization (DRX) occurs. The critical strain for DRX is determined by analysis of flow stress curves. The ratio of the critical strain to the peak strain falls in the range of 0.4-0.5. At low temperatures and high strai rates, the deformation become macroscopically inhomogeneous, and the fracture of the specimens is accompanied by shear banding. Grain refinement resulting from DRX is less effective at high temperatures due to rapid grain growth. It is also shown that there is no difference between peak stress and stable state stress at high temperatures and lower strain rates, presenting the feature of continuous dynamic recrystallization (CDRX).

Microstructural Evolution of Magnesium Alloy during Hot Compression

2013 ◽  
Vol 446-447 ◽  
pp. 158-163
Author(s):  
Xing Cheng Li ◽  
Ya Lin Lu ◽  
Jiang Tao Wang ◽  
Lin Dou
Keyword(s):  
Elevated Temperature ◽  
Flow Stress ◽  
Magnesium Alloy ◽  
Dynamic Recrystallization ◽  
Process Parameters ◽  
Deformation Mechanism ◽  
Deformation Process ◽  
Hot Compression ◽  
Strain Rates ◽  
Dynamic Recrystallisation

Hot compression of AZ3l magnesium alloy was carried out at deformation temperatures of 523-723K and strain rates of 0.01-10s-1. The effects of deformation process on the microstructure and flow stress were investigated. The flow stress curves showed the characteristic of dynamic recrystallization (DRX) with deformation process parameters. Optical microscopy and TEM observations indicated that dynamic recrystallisation and twins structure were found during hot compression. Deformation mechanism of AZ3l magnesium alloy at elevated temperature was discussed in this paper.

Flow Stress Constitutive Equation of AZ31 Magnesium Alloy for Hot Compression

2011 ◽  
Vol 328-330 ◽  
pp. 1614-1618 ◽  
Author(s):  
Wen Hua Wu ◽  
Yan Lou
Keyword(s):  
Flow Stress ◽  
Magnesium Alloy ◽  
Constitutive Equation ◽  
Dynamic Recrystallization ◽  
Dynamic Recovery ◽  
Hot Compression ◽  
Az31 Magnesium Alloy ◽  
Multivariate Nonlinear Regression ◽  
Relative Errors ◽  
Kinetics Of

The AZ31 magnesium alloy flow stresses have been investigated in the strain rates of 0.03~3s-1and temperature range of 300~400°C. The result showed that dynamic recovery and dynamic recrystallization occurred obviously during the hot compression of AZ31 magnesium alloy. In order to represent the flow stress of plastic deformation accurately, the constitutive equation was built by using the dynamic recovery model and dynamic recrystallization model, and its parameters of the constitutive equation were determined by multivariate nonlinear regression analysis. The two-step constitutive equation not only expressed the variation of flow stress with strain rate, deformation temperature and strain, but also revealed the characteristic of dynamic recrystallization kinetics of AZ31 magnesium alloy. Its accuracy was higher than the flow stress of hyperbolic sine model, and the maximum relative errors of two constitutive equation models calculation values compared with experiment data were 5% and 6.5% respectively.

Study on Flow Stress Characteristics of AZ31B under Multi-Stage Hot Deformation

2013 ◽  
Vol 310 ◽  
pp. 117-123
Author(s):  
Xin Tong Wu ◽  
Zhao Yang Jin ◽  
Juan Liu ◽  
Xin Huang
Keyword(s):  
Flow Stress ◽  
Magnesium Alloy ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Hot Deformation ◽  
Temperature Jump ◽  
Peak Strain ◽  
Stored Energy ◽  
Deformation Degree ◽  
Multi Stage

In order to improve the understanding of the rheological behavior of magnesium alloy AZ31B under multi-stage hot deformation, a series of isothermal compressing experiments with height reduction of 60% were performed at the temperatures of 250°C, 300°C, 350°C and 400°C and the strain rates of 0.01 s−1and 0.1 s−1 on a Gleeble 1500 thermo-mechanical simulator. The effects of temperature (jump), strain rate (jump), deformation degree and deformation interval time on the flow stress characteristics are investigated and discussed. It is shown that in the dual-stage deformation process with temperature jump or strain rate jump, values of peak stress and peak strain at the second-stage are lower than those at single-stage. The reason for this change is due to the deformation stored energy still retained in the material after its release during the first-stage deformation and deformation interval, such as dynamic recrystallization, meta-dynamic recrystallization, static recovery and static recrystallization The deformation resistance of the multi-stage deformation of AZ31B can be reduced by increasing the deformation degree at the first-stage or the deformation interval because it leads to adequate release of deformation stored energy, which improves the plastic formability of magnesium alloy.

Dynamic Recrystallization of 3104 Aluminum Alloy during Isothermal Compression Deformation at Elevated Temperatures

2007 ◽  
Vol 546-549 ◽  
pp. 1061-1064 ◽  
Author(s):  
Guang Jie Huang ◽  
Qing Liu ◽  
Ling Yun Wang ◽  
Xiao Hui Yin
Keyword(s):  
Flow Stress ◽  
Dynamic Recrystallization ◽  
Elevated Temperatures ◽  
Critical Value ◽  
Strain Rates ◽  
Peak Strain ◽  
Isothermal Compression ◽  
Hollomon Parameter ◽  
Compression Deformation ◽  
Work Hardening Rate

The dynamic recrystallization characteristic of 3104 alloy has been investigated by isothermal compression deformation at temperatures from 573K to 773K under constant strain rates ranges from 10-3s-1 to 1s-1. It was shown that the form of flow stress curves were very sensitive to temperature and strain rate. At high temperatures and low strain rates, dynamic recrystallization of 3104 alloy deformation occured. The critical value for dynamic recrystallization start was determined from an inflection point that was observed in the plot of work hardening rate vs. flow stress and verified metallograhically based on quenching samples interrupted during deformation. In the experimental domain studied, the ratio of the critical strain for the initiation of dynamic recrystallization to that of the peak strain falled in the range 0.4-0.6. Furthermore, the dependence of εc on Zener-Hollomon parameter( Z) has been developed.

Hot Compressive Deformation of Rheocast AZ31 Magnesium Alloy

2006 ◽  
Vol 116-117 ◽  
pp. 742-745 ◽  
Author(s):  
Bi Cheng Yang ◽  
Shao Ming Zhang ◽  
Jun Xu ◽  
Li Kai Shi ◽  
Z. Fan
Keyword(s):  
Flow Stress ◽  
Magnesium Alloy ◽  
Dynamic Recrystallization ◽  
Deformation Temperature ◽  
Cast Billet ◽  
Strain Rates ◽  
Cast Sample ◽  
Cast Specimen ◽  
Twin Screw ◽  
The Relationship

The billet of magnesium AZ31B was made by twin-screw rheo-cast, and the specimen cut from the rheo-cast billet and normal cast billet were compressed in Gleeble-3000 hot simulator. The deformation temperature was 300, 350, and the strain rates were 0.001~1s-1. The relationship among flow stress, deformation temperature and strain rates were analyzed. The variation of the microstructure was observed and compared after the specimen was hot compressed. The results show that the surface of the rheo-cast specimen is much more smooth than the normal cast specimen after the compression. The dynamic recrystallization had taken place during the compression and the recrystallized grain of rheo-cast sample is more tiny than normal cast specimen.

Constitutive Modeling for Flow Stress Behavior of Nimonic 80A Superalloy During Hot Deformation Process

2016 ◽  
Vol 35 (3) ◽  
pp. 327-336 ◽  
Author(s):  
Sendong Gu ◽  
Liwen Zhang ◽  
Chi Zhang ◽  
Wenfei Shen
Keyword(s):  
Flow Stress ◽  
Constitutive Model ◽  
Hot Deformation ◽  
Critical Strain ◽  
Volume Fraction ◽  
Constitutive Models ◽  
Avrami Equation ◽  
Peak Strain ◽  
Compression Tests ◽  
Nimonic 80A

AbstractThe hot deformation characteristics of nickel-based alloy Nimonic 80A were investigated by isothermal compression tests conducted in the temperature range of 1,000–1,200°C and the strain rate range of 0.01—5 s–1on a Gleeble-1500 thermomechanical simulator. In order to establish the constitutive models for dynamic recrystallization (DRX) behavior and flow stress of Nimonic 80A, the material constantsα,nand DRX activation energyQin the constitutive models were calculated by the regression analysis of the experimental data. The dependences of initial stress, saturation stress, steady-state stress, dynamic recovery (DRV) parameter, peak strain, critical strain and DRX grain size on deformation parameters were obtained. Then, the Avrami equation including the critical strain for DRX and the peak strain as a function of strain was established to describe the DRX volume fraction. Finally, the constitutive model for flow stress of Nimonic 80A was developed in DRV region and DRX region, respectively. The flow stress values predicted by the constitutive model are in good agreement with the experimental ones, which indicates that the constitutive model can give an accurate estimate for the flow stress of Nimonic 80A under the deformation conditions.

Characteristics of Dynamic Recrystallization during Hot Deformation for High Nitrogen Stainless Steels

2012 ◽  
Vol 715-716 ◽  
pp. 115-121
Author(s):  
Hai Wen Luo ◽  
Xu Dong Fang ◽  
Rui Zhen Wang ◽  
Zhan Yin Diao
Keyword(s):  
Dynamic Recrystallization ◽  
Stainless Steels ◽  
Hot Deformation ◽  
Strain Rates ◽  
Peak Strain ◽  
High Nitrogen ◽  
Flow Curves ◽  
Grain Sizes ◽  
Nitrogen Contents ◽  
High Nitrogen Stainless Steel

Dynamic recrystallization was studied for the stainless steels with nitrogen contents of 0.56% to 1.08% during hot deformation at temperatures of 900~1200 with strain rates ranging from 0.003 to 42 s-1. It was found that flow stress could increase remarkably with increasing nitrogen content. Flow curves during the deformation by 0.1~42/s at temperatures of 900~1200°C show a single peak, indicating the occurrence of dynamic recrystallization during deformation. The peak strain seems to decrease with increasing N content, suggesting that higher content of N facilitates dynamic recrystallization. The quenched microstructures were analyzed by optical microscopy, EBSD and TEM. The recrystallized grain sizes on the quenched specimens were measured and its dependence on temperature and strain rate was analyzed. At high temperature, continuously dynamically recrystallized microstructures were observed; whilst at low temperature, necklace-like partially recrystallized microstructures were found. Key words: High nitrogen stainless steel; dynamic recrystallization; stress-strain curves

Prediction of flow stress and textures of AZ31 magnesium alloy at elevated temperature

2014 ◽  
Vol 94 (29) ◽  
pp. 3353-3367 ◽  
Author(s):  
Hesam Askari ◽  
John P. Young ◽  
David P. Field ◽  
Ghassan Kridli ◽  
Hussein M. Zbib
Keyword(s):  
Elevated Temperature ◽  
Flow Stress ◽  
Magnesium Alloy ◽  
Az31 Magnesium Alloy
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