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.

scholarly journals Constitutive Relationship for Hot Deformation of TB18 Titanium Alloy

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Qiang Fu ◽  
Wuhua Yuan ◽  
Wei Xiang
Keyword(s):  
Titanium Alloy ◽  
Flow Stress ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Hot Deformation ◽  
Flow Behavior ◽  
Peak Stress ◽  
Constitutive Relationship ◽  
Flow Localization ◽  
Phase Zone

In the present work, the hot deformation behavior of TB18 titanium alloy was investigated by isothermal hot compression tests with temperatures from 650 to 880°C and strain rates from 0.001 to 10 s−1. The flow curves after friction and temperature correction show that the peak stress decreased with the temperature increase and the strain rate decrease. Three typical characteristics of flow behavior indicate the dynamic softening behavior during hot deformation. At a strain rate of 0.001∼0.01 s−1, the flow stress continues to decrease as the strain rate increases after the flow stress reaches the peak stress; the flow softening mechanism is dynamic recovery and dynamic recrystallization at a lower temperature and dynamic recrystallization at a higher temperature. The discontinuous yielding phenomenon could be seen at a strain rate of 1 s−1, dynamic recrystallization took place in the β single-phase zone, and flow localization bands were observed in the α + β two-phase zone. At a higher strain rate of 10 s−1, the flow instabilities were referred to as the occurrence of flow localization by adiabatic heat. Constitutive equation considering the compensation of strain was also established, and the results show high accuracy to predict the flow stress with the correlation coefficient of 99.2% and the AARE of 6.1%, respectively.

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.

Hot Compression Deformation Behavior of Mg-Gd-Y-Zn-Zr Alloy

2014 ◽  
Vol 680 ◽  
pp. 15-22 ◽  
Author(s):  
Guang Lu ◽  
Zhi Ping Xie ◽  
Zhi Min Zhang ◽  
Yong Biao Yang ◽  
Bao Cheng Li
Keyword(s):  
Flow Stress ◽  
Magnesium Alloy ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Great Influence ◽  
Peak Stress ◽  
Maximum Error ◽  
Continuous Dynamic Recrystallization ◽  
Stress Behaviors ◽  
Continuous Dynamic

The deformation behaviors of as-cast Mg-11Gd-2Y-Zn-Zr magnesium alloy were investigated by compression test with Gleeble-1500 thermal simulator at temperature of 623-753K and strain rate of 0.01-0.5 s-1. The flow stress behaviors of the magnesium alloy were carried out at a strain of 0.7. The strain rate and deformation temperature had great influence on the flow stress behaviors. The flow stress increases with increasing strain rate and decreasing temperature. The flow stress has more than one peak stress at a strain rate of 0.5s-1showing continuous dynamic recrystallization (DRX) mechanism, while other flow stresses exhibited only one peak stress indicating discontinuous dynamic recrystallization (DDRX) mechanism. It was also found that the flow stress behavior could be described by the hyperbolic sine constitutive equation, in which the determined average activation energy is 273.426 kJ·mol-1. The maximum error value between calculated value and experimental value is 5.5%. The deformation map was also established, and the best parameter for hot working was found to be 0.1s-1/753k approximately.

High Temperature Deformation Behaviour and Processing Maps of AZ81 Magnesium Alloy

2011 ◽  
Vol 686 ◽  
pp. 168-175 ◽  
Author(s):  
Hui Min Liao ◽  
Ming Zeng ◽  
Si Yuan Long ◽  
Han Xue Cao
Keyword(s):  
High Temperature ◽  
Flow Stress ◽  
Magnesium Alloy ◽  
Strain Rate ◽  
Hot Deformation ◽  
Flow Instability ◽  
Temperature Deformation ◽  
Stable Phase ◽  
Processing Temperature ◽  
Processing Maps

The hot compression deformation behavior of AZ81 magnesium alloy was studied with Gleeble-1500 thermal simulation machine at the strain rate of 0.003 ~ 3.0s-1 and temperature of 340 ~ 430 °C. The results show that, the flow stress decreases when the deformation temperature increases and strain rate decreases; the peak stress increases with decrease of the temperature and the increase of the strain rate; the critical strain that comes into stable phase increases obviously. It is that the high temperature flow stress model of AZ81 magnesium alloy is constructed by introduceing Zener-Hollomon parameters, its average deformation activation energy is 169.48 kJ / mol. Processing maps of AZ81 magnesium alloy is also calculated and analyzed by the dynamic model of the material. Useing hot deformation processing maps, the flow instability zone is determined and the best process parameters access to the test parameters during hot deformation are as follow: thermal processing temperature range of 380 °C ~ 420 °C, strain rate range of 0.01 ~ 0.03 S-1.

Establishment of Flow Stress Model of EW75 Alloy

2013 ◽  
Vol 423-426 ◽  
pp. 241-246
Author(s):  
Ming Long Ma ◽  
Kui Zhang
Keyword(s):  
Mathematical Model ◽  
Flow Stress ◽  
Magnesium Alloy ◽  
Strain Rate ◽  
Strain Rate Range ◽  
Strain Rates ◽  
Stress Strain ◽  
Deformation Degree ◽  
Maximum Deformation ◽  
The Mathematical Model

The behavior evolvement of Mg-7.22Gd-4.84Y-1.26Nd-0.58Zr (EW75) magnesium alloy during the hot deformation process was discussed. The flow stress behavior of magnesium alloy over the strain rate range 0.002s-1to 2s-1and the temperature range 623K to 773K had been researched on Gleeble-1500D hot simulator under the maximum deformation degree 60%. A mathematical model was established to predict the stress-strain curves of this alloy during deformation. The experimental results showed that the stress-strain curves were obviously affected by the strain rates and deformation temperatures. The mathematical model could predict the stress-strain curves when the strain rates were under 0.2-1, but there was significant error in some of stress-strain curves when the strain-rate was 2-1by the reason of deformation temperature rising.

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).

Compressing Deformation and Microstructure of AZ61 Magnesium Alloy

2014 ◽  
Vol 1015 ◽  
pp. 203-206
Author(s):  
Quan Li ◽  
Jin Yang ◽  
Wen Jun Liu ◽  
Su Qin Luo ◽  
Ren Ju Cheng ◽  
...  
Keyword(s):  
Grain Size ◽  
Flow Stress ◽  
Magnesium Alloy ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Deformation Temperature ◽  
Hot Compression ◽  
Compression Tests ◽  
Az61 Magnesium Alloy

Hot compression tests of AZ61 magnesium alloy were performed on gleeble1500D at strain rate ranged in 0.01~1s-1 and deformation temperature 350~400°C.The results show that the flow stress and microstructures strongly depend on the deformation temperature and the strain rate. When the temperature was reduced and the strain rate was enhanced, the area after dynamic recrystallization was enhanced, and the average dynamically recrystallied grain size reduce. But the dynamically recrystallied grain size was not well-proportioned. In this paper the 350°C×1s-1 was suggested.

Flow Behavior and Microstructural Evolution of a 7039 Aluminum Alloy during Hot Deformation

2011 ◽  
Vol 239-242 ◽  
pp. 2395-2398 ◽  
Author(s):  
Hui Zhong Li ◽  
Xiao Peng Liang ◽  
Min Song ◽  
Min Zeng
Keyword(s):  
Aluminum Alloy ◽  
Flow Stress ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Microstructural Evolution ◽  
Hot Deformation ◽  
Deformation Temperature ◽  
Flow Behavior ◽  
Thermal Simulation ◽  
Strain Rates

The flow behavior of a 7039 aluminum alloy and the corresponding microstructural evolution during hot deformation were studied by Gleeble-1500 thermal simulation tests, EBSD and TEM observations with temperatures ranging from 300 °C to 500 °C under strain rates from 0.01 s-1 to 10 s-1. It has been shown that the flow stress increases with the decrease in the deformation temperature and increase in the strain rate. The degree of dynamic recrystallization (DRX) increases with the increase in the deformation temperature and strain rate in 7039 aluminum alloy. The complete dynamic recrystallization occurs at 500 °C with a strain rate of 10 s-1.

Hot deformation behavior and dynamic recrystallization constitutive modeling of Al–Cu–Mg powder compacts processed by extrusion at elevated temperatures

2020 ◽  
pp. 146442072097132
Author(s):  
Katti Bharath ◽  
Asit Kumar Khanra ◽  
MJ Davidson
Keyword(s):  
Powder Metallurgy ◽  
Flow Stress ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Relative Density ◽  
Constitutive Equations ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
Peak Flow ◽  
Hot Deformation Behavior

The deformation behavior of Al–Cu–Mg sintered preforms has been investigated by extrusion in the temperature range of 450–550°C and strain rate range of 0.1–0.3 s−1, respectively. The aim of this study is to analyze the effect of initial preform relative density on the hot deformation behavior and to model and predict the flow stress of extruded samples using constitutive equations. The true stress–strain curves exhibit three stages of deformation, which represent work hardening, dynamic recovery, and dynamic recrystallization during deformation at different temperatures, strain rates, and initial preform relative densities of 70%, 80%, and 90%, respectively. The results show that the flow stress values are influenced by initial preform relative density, deformation temperature, and strain rate. Microstructural examination of extruded specimens has been performed by optical microscopy and scanning electron microscopy. Arrhenius-type constitutive equations are developed to predict the flow stress of hot-extruded powder metallurgy processed aluminum alloy (Al–4%Cu–0.5%Mg). Zener–Hollomon parameter is used to explain the relationship between peak flow stress, temperature, and strain rate in an exponential equation containing the deformation activation energy and material constants. Subsequently, the statistical indicators correlation coefficient ( R) and the average absolute relative error are assessed to confirm the validity of constitutive equations. The results indicate the experimental and predicted peak flow stress values are in good agreement, which indicate the accuracy and reliability of the developed model for powder metallurgy processed Al–4%Cu–0.5%Mg preforms.

scholarly journals Characterization of Hot Deformation Behavior and Processing Maps of Mg-3Sn-2Al-1Zn-5Li Magnesium Alloy

Metals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1262 ◽  
Author(s):  
Yuhang Guo ◽  
Yaodong Xuanyuan ◽  
Chunnan Lia ◽  
Sen Yang
Keyword(s):  
Magnesium Alloy ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Hot Deformation ◽  
Processing Maps ◽  
Compression Tests ◽  
Softening Mechanism ◽  
Signal Peak ◽  
The Operating Mechanism ◽  
The Stability

The dynamic microstructure evolution of Mg-3Sn-2Al-1Zn-5Li magnesium alloy during hot deformation is studied by hot compression tests over the temperature range of 200–350 °C under the strain rate of 0.001–1 s−1, whereafter constitutive equations and processing maps are developed and constructed. In most of cases, the material shows typical dynamic recrystallization (DRX) features, with a signal peak value followed by a gradual decrease. The value of Q (deformation activation energy) is 138.89414 kJ/mol, and the instability domains occur at high strain rate but the stability domains are opposite, and the optimum hot working parameter for the studied alloy is determined to be 350 °C/0.001 s−1 according to the processing maps. Within 200–350 °C, the operating mechanism of dynamic recrystallization (DRX) of Mg-3Sn-2Al-1Zn-5Li alloy during hot deformation is mainly affected by strain rate. Dynamic recrystallization (DRX) structures are observed from the samples at 300 °C/0.001 s−1 and 350 °C/0.001 s−1, which consist of continuous DRX (CDRX) and discontinuous DRX (DDRX). However, dynamic recovery (DRV) still dominates the softening mechanism. At the grain boundaries, mass dislocation pile-ups and dislocation tangle provide sites for potential nucleation. Meanwhile, flow localization bands are observed from the samples at 200 °C/1 s−1 and 250 °C/0.1 s−1 as the main instability mechanism.

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