scholarly journals Flow Stress Curve Modification and Constitutive Model of 20CrMoA Steel during Warm Deformation

Metals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1602
Author(s):  
Sheng Xu ◽  
Xuedao Shu ◽  
Shuxin Li ◽  
Ji Chen
Keyword(s):  
Flow Stress ◽  
Constitutive Model ◽  
Strain Rate ◽  
Deformation Temperature ◽  
True Strain ◽  
Processing Parameters ◽  
Flow Softening ◽  
Warm Deformation ◽  
Temperature Range ◽  
Lower Temperature

The warm deformation behavior of 20CrMoA steel at the temperature of 873–1123 K and the strain rate of 0.01−10 s−1 was investigated to obtain its processing property and optimum processing parameters. The true stress-true strain curves showed that flow stress reaches the peak rapidly, followed by slow decrease till reaching a steady state. This suggests a flow softening of dynamic recovery. The stress dropped with increasing deformation temperature and decreasing strain rate. The reduction became more distinct at lower temperature and higher strain rate due to flow softening caused by deformation heat. In the temperature range of 873–973 K, the deformation of 20CrMoA steel was more sensitive to temperature, and the average decline rate of steady stress was 6.9 times larger than that in the temperature range of 1023–1123 K. After modifying the stress curves, a constitutive model was developed for different deformation temperature ranges based on modified curves. The model was in good agreement with the experimental results.

Experimental and Physical-Based Constitutive Model Study of FCC Metal Over Wide Temperature and Strain Rate Ranges

2015 ◽  
Author(s):  
Jianchao Yu ◽  
Gang Wang ◽  
Jianwei Qin ◽  
Maobing Shuai ◽  
Yiming Rong
Keyword(s):  
Aluminum Alloy ◽  
Flow Stress ◽  
Constitutive Model ◽  
Strain Rate ◽  
Split Hopkinson Pressure Bar ◽  
Dynamic Deformation ◽  
True Strain ◽  
Experimental Results ◽  
Deformation Behaviors ◽  
Fcc Metal

Dynamic deformation behaviors of aluminum alloy Al1060 (FCC metal) are studied by the uniaxial compression tests on the Split Hopkinson Pressure Bar over wide temperature and strain rate ranges. The experimental results show that the flow stress is both strain rate and temperature sensitivity. The flow stress decreases with increasing temperature when the strain rate keeps constant. When the temperature keeps constant, the flow stress increases with increasing strain rate. Considering the thermal activation of dislocation gliding in the dynamic deformation process, a physical-based constitutive model is developed based on the experimental results to predict the flows stress of Al1060 at a given strain rate and temperature. The material constants in the constitutive model are determined by the nonlinear genetic algorithm. The true stress-true strain curves predicted by the proposed constitutive models can give good correlations with the experimental results, which confirm that the proposed physical-based constitutive can accurately characterize the dynamic deformation behaviors of the studied aluminum alloy Al1060.

scholarly journals The hot flow behavior of Al-2wt.%Cu-1wt.%Mn alloy based on Gleebe-3800 hot compression simulation

2018 ◽  
Vol 207 ◽  
pp. 03016
Author(s):  
JinLong Chen ◽  
Hengcheng Liao ◽  
Heting Xu
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Deformation Temperature ◽  
Peak Flow ◽  
Flow Behavior ◽  
True Strain ◽  
Strain Rate Range ◽  
Compressive Test ◽  
Test Parameters ◽  
Deformation Activation Energy

Flow behavior of Al-2.0wt.%Cu-1.0wt.%Mn aluminum alloy was investigated by hot compressive test using a Gleebe-3800 thermal simulator. The test parameters about temperature and strain rate range from 573K to 773 K and from 0.01s-1 to 5s-1, respectively, and the true strain is up to 0.6. It can be seen that the peak flow stress increases with increasing the strain rate and decreases by deformation temperature. And the deformation activation energy of Al-2.0wt.%Cu-1.0wt.%Mn alloy is 183.02KJ/mol. A constitutive equation has been constructed to predict the hot deformation behavior, and correlate the peak flow stress predicted with strain rate and deformation temperature.

High Temperature Deformation Behavior of 25Cr5MoA Nitriding Steel

2011 ◽  
Vol 399-401 ◽  
pp. 240-244
Author(s):  
Yue Zang ◽  
Shu Xia Li ◽  
Yi Kun Yang ◽  
Xue Ping Ren
Keyword(s):  
High Temperature ◽  
Flow Stress ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Deformation Temperature ◽  
True Strain ◽  
Strain Curve ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Deformation Degree

The high temperature deformation law of nitriding steel 25Cr5MoA over the strain rate range 0.001S-1~20S-1and temperature range 850°C to 1150°C was studied in the thermal simulation testing machine Gleeble-1500. Under a certain strain rate and a certain deformation degree, the flow stress decreased with the increase of deformation temperature. Work hardening of nitriding steel 25Cr5MoA was strong when the true strain was less than 0.2, otherwise the flow stress increased slowly, even dropped. High temperature deformation flow stress of nitriding steel 25Cr5MoA was influenced by the deformation temperature and strain rate. When the strain rate was 0.1S-1, true stress-true strain curve exhibited a dynamic recrystallization model, and with the increase of deformation temperature, peak flow stress shift left. When deformation degree was 0.69, the strain rate was 1S-1, and when deformation temperature was in the region of 850°C~1050°C, true stress-true strain curve exhibited a dynamic recovery model. And when the deformation temperature was in the region of 1100°C~1150°C, it showed a dynamic recrystallization model. Dynamic recrystallization diagrams of nitriding steel 25Cr5MoA were also established.

Study of Hot Deformation Behavior in GH4169 Superalloy

2013 ◽  
Vol 712-715 ◽  
pp. 658-661 ◽  
Author(s):  
Dong Xu Wen ◽  
Y.C. Lin ◽  
Ming Song Chen
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Work Hardening ◽  
Hot Deformation ◽  
Deformation Temperature ◽  
Flow Behavior ◽  
Peak Stress ◽  
Processing Parameters ◽  
Initial Increase ◽  
Gh4169 Superalloy

In order to study the workability and optimize hot forming processing parameters for GH4169 superalloy, the hot deformation behaviors are investigated. The results show that the flow stress strongly depends on the strain rate, deformation temperature and strain. With the increase of strain rates and the decrease of deformation temperature, the flow stress increases. The flow stress exhibits an initial increase with the strain until a peak stress value, showing a obvious work hardening. After the peak stress, increasing strain results in the decrease of stress, indicating a dynamic flow softening. A revised constitutive equation incorporating the effects of temperature, strain rate and work-hardening rate of the material is established by compensation of strain. A good agreement between the measured and predicted results shows that the established model can give an accurate prediction of the flow behavior of GH4169 superalloy.

Study of Hot Compression Behavior of ZK60 Magnesium Alloy at Elevated Temperature

2010 ◽  
Vol 154-155 ◽  
pp. 1-10 ◽  
Author(s):  
Yun Bin He ◽  
Qing Lin Pan ◽  
Xiao Yan Liu ◽  
Wen Bin Li
Keyword(s):  
Flow Stress ◽  
Magnesium Alloy ◽  
Constitutive Equation ◽  
Strain Rate ◽  
Deformation Temperature ◽  
True Strain ◽  
Hot Compression ◽  
Compression Behavior ◽  
Zk60 Magnesium Alloy ◽  
Softening Stage

The hot compression behavior of ZK60 magnesium alloy was investigated at the temperatures from 523 to 673K and strain rates from 0.001 to 1s-1 on Gleeble-1500 thermal simulator. The results show that flow stress of ZK60 magnesium alloy decreases with the increase of deformation temperature and the decrease of strain rate. The flow stress curves obtained from experiments can be described in four different stages, i.e., work hardening stage, transition stage, softening stage and steady stage. For higher temperature and lower strain rate, the transition and softening stage are less obvious. The onset of dynamic recrystallization (DRX) occurred before the stress peak in true stress-true strain curves. The critical stress characterizing the onset of DRX rises with the increase of strain rate and/or the decrease of deformation temperature. The constitutive equation of ZK60 magnesium alloy during hot compression was constructed allowing for the effect of true strain on materials constants. The predicted stress-strain curves according to the constitutive equation are in good agreement with experimental results.

Flow Stress and Microstructural Evolution of AM50 Alloy during Upsetting Forging Tests at High Temperature

2005 ◽  
Vol 488-489 ◽  
pp. 815-818
Author(s):  
Yun Qi Yan ◽  
Lian Zhou ◽  
Chang Qi Chen
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Dynamic Balance ◽  
True Strain ◽  
Peak Stress ◽  
Strain Rate Range ◽  
True Stress ◽  
Initial Time ◽  
Am50 Alloy ◽  
Lower Temperature

Flow stress and microstructures evolution of AM50 alloy during upsetting forging tests were investigated in this paper. In upsetting forging deformation, cylindrical billets of AM50 alloy as-cast were compressed in the temperature range of 250°C to 350°C and strain rate range of 1.1×10-3s-1 to 2.8×10-2s-1. Under the deformed conditions, the true stress-true strain curves indicated that the true stress increased quickly at the initial time, then stayed at certain value for a short duration and increased continuously at lower temperature and high strain rate. It should be noted that the true stress kept the dynamic balance with the true strain at higher temperature and lower strain rate that the true stress obeyed the regulation as the same as the ordinary materials. The peak stress at all conditions increased with the strain rate increasing and the forging temperature decreasing. A great many recrystallized grains and dislocations were observed in the deformed specimens of AM50 alloy. The grain size of the deformed specimens decreased with decreasing forging temperature and increasing the deformation.

Constitutive Equation of ZL201 Alloy during the Semi-Solid Thixotropic Compression

2011 ◽  
Vol 418-420 ◽  
pp. 1274-1278
Author(s):  
Shu Zhen Shang ◽  
Xiao Ling Tang ◽  
Gui Min Lu ◽  
Wan Ning Zhang ◽  
Jiao Jiao Wang
Keyword(s):  
Experimental Data ◽  
Flow Stress ◽  
Constitutive Equation ◽  
Strain Rate ◽  
Deformation Behavior ◽  
Deformation Temperature ◽  
Processing Parameters ◽  
Experimental Results ◽  
Semi Solid ◽  
The Relationship

Effects of deformation temperature and strain rate on deformation behavior of semi-solid ZL201 alloy were investigated on Gleeble3800 thermal-mechanical simulator. On basis of the experimental data of semi-solid ZL201, a model of was established to describe the relationship between the processing parameters and flow stress, which showed that the experimental results and calculation ones fitted well. The suitable conditions of this model for semi-solid ZL201 alloy were that the temperature range was 547°C-649°C and that of the strain rate was 0.1 s-1-5s-1.

Hot Compressive Behavior of Ti-3.0Al-3.7Cr-2.0Fe Titanium Alloy at Different Strain Rates

2012 ◽  
Vol 560-561 ◽  
pp. 1072-1077
Author(s):  
Guo Wang ◽  
Song Xiao Hui ◽  
Wen Jun Ye
Keyword(s):  
Titanium Alloy ◽  
Flow Stress ◽  
Strain Rate ◽  
Early Stage ◽  
True Strain ◽  
Stable State ◽  
Constitutive Relationship ◽  
Test Machine ◽  
Strain Rates ◽  
Temperature Range

The characteristics of hot compression deformation of Ti-3.0Al-3.7Cr-2.0Fe titanium alloy have been studied by Gleeble−1500D thermal simulated test machine in the strain rates range 0.01～10s−1 and temperature range 800～950°C. The true stress-true strain curves show that the peak flow stress decrease with increase temperature and decrease strain rate. At the temperature range in the article, there is a distinct peak in the flow stress in the early stage deformation followed by a stable state at high strains. The variation of flow stress with temperature and strain rate follows the standard kinetic rate equation and the apparent activation energy is estimated to be about 214.22KJ•mol-1. The constitutive relationship of Ti-3.0Al-3.7Cr-2.0Fe alloy is obtained on the base of Arrhenius equation at the experimental conditions.

scholarly journals MECHANICAL BEHAVIOR AND MICROSTRUCTURE EVOLUTION OF THE Ti-3Al-5Mo-4.5V ALLOY AT AN ELEVATED DEFORMATION TEMPERATURE

2021 ◽  
Vol 55 (3) ◽  
Author(s):  
Menglan Shen ◽  
Yuanming Huo ◽  
Tao He ◽  
Yong Xue ◽  
Yujia Hu ◽  
...  
Keyword(s):  
Titanium Alloy ◽  
Strain Rate ◽  
Microstructure Evolution ◽  
Deformation Temperature ◽  
High Performance ◽  
Warm Deformation ◽  
Deformation Region ◽  
Temperature Range ◽  
Softening Mechanism ◽  
Lower Strain

A high-performance titanium alloy requires a fine and homogenous microstructure. The rational deformation process parameters of the Ti-3Al-5Mo-4.5V (TC16) titanium alloy can contribute to achieving this important microstructure. Hot-compression experiments were performed at temperatures in the range 100–800 °C and at strain rates of 0.1 s–1 to 10.0 s–1. The effects of deformation temperatures and deformation rates on the mechanical behaviour and microstructure evolution were analysed and discussed. The softening mechanism of the Ti-3Al-5Mo-4.5V alloy at an elevated deformation temperature was revealed. Experimental results showed that 500 °C is the critical deformation temperature to distinguish the warm-deformation region of 100–400 °C and the hot-deformation region of 500–800 °C. The softening mechanism is dominated by -phase spheroidization in the temperature range 100–400 °C with a higher strain rate of 10.0 s–1. The softening mechanism is dominated by a local temperature rise in the temperature range 500–800 °C with a lower strain rate of 0.1 s–1.

scholarly journals Flow Behavior Characteristics and Processing Map of Fe-6.5wt.%Si Alloys during Hot Compression

2018 ◽  
Author(s):  
Shibo Wen ◽  
Chaoyu Han ◽  
Bao Zhang ◽  
Yongfeng Liang ◽  
Feng Ye ◽  
...  
Keyword(s):  
High Temperature ◽  
Flow Stress ◽  
Strain Rate ◽  
Processing Map ◽  
Flow Behavior ◽  
True Strain ◽  
Processing Parameters ◽  
Hot Compression ◽  
Strain Rates ◽  
Rate Region

The flow behavior of Fe-6.5wt.%Si alloys during hot compression was investigated at temperatures 650–950 °C and strain rates 0.01–10 s-1. The results showed that the flow stress depended distinctly on the deformation temperatures and strain rates. The flow stress and work hardening rate increased with the decrease of temperature and the increase of strain rate. The activation energy under all the deformation conditions was calculated to be 410 kJ/mol. The constitutive equation with hyperbolic sine function and Zener–Hollomon parameter was developed. The peak stress, critical stress, and steady-state stress could be represented as σ=A+Bln(Z/A). Dynamic recrystallization occurred under the deformation conditions where the values of Z were lower than 1020. Processing maps were established to optimize the processing parameters. The power dissipation efficiency decreased in the high temperature and low strain rate region, increased in the high temperature and high strain rate region, and remained unchanged in other regions with the increase of true strain. Furthermore, the unstable area expanded. The true strain of 0.7 was the optimum reduction according to the processing map. Based on the analysis of surface quality, microstructures, and ordered structures, the optimized processing parameters for the Fe-6.5wt.%Si alloys were the temperature and strain rate of higher than 900 °C and 0.01–10 s-1, respectively, or 800–900 °C and lower than 0.4 s-1, respectively.

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