Microstructure and Stress Variation of Semisolid 7A04 Alloy during Isothermal Compression

2012 ◽  
Vol 426 ◽  
pp. 101-105
Author(s):  
Hui Yang ◽  
Wen Tong Tian
Keyword(s):  
Strain Rate ◽  
Grain Boundaries ◽  
Compressive Stress ◽  
Deformation Temperature ◽  
Solid Phase ◽  
True Strain ◽  
Peak Stress ◽  
True Stress ◽  
Stress Variation ◽  
Rate Analysis

The microstructure and stress variation of semisolid 7A04 alloy have been studied through unconstrictive isothermal compressing test. The results show that the relationships between true stress and true strain at different deformation temperatures and strain rates are the same, and the peak stress in the curve of true stress and true strain mainly depends on deformation temperature and strain rate. Analysis on the microstructure of compressive specimen demonstrates that segregation of liquid-solid phase is mainly affected by strain rate and deformation temperature. There are mainly two kinds of flow in liquid phase: either from the region with relatively large hydrostatic compressive stress to the region with relatively small hydrostatic compressive stress or from the grain boundaries perpendicular to the compressive axis to the grain boundaries with a certain directional angle to the compressive direction. Based on the above results, the microstructure and stress variation mainly depend on deformation temperature, strain rate and stress state.

Study on Thermal Deformation Behavior of Cu-P Weathering Steel

2011 ◽  
Vol 704-705 ◽  
pp. 124-128
Author(s):  
Xin Zhang ◽  
Yi Xiong
Keyword(s):  
Strain Rate ◽  
Deformation Behavior ◽  
Deformation Temperature ◽  
Thermal Deformation ◽  
True Strain ◽  
True Stress ◽  
Weathering Steel ◽  
Strain Rates ◽  
Deformation Equation ◽  
Temperature Strain

Using thermal simulator (Gleeble 1500D), the thermal deformation behavior of Cu-P weathering steel containing Cr, Ni, Mo under the conditions of various deformation temperatures and strain rates was studied. The true stress-true strain curves at various thermal deformation conditions were got, and the thermal deformation equation was established. Then the microstructure features of the steel under various deformation temperatures and strain rates were analyzed when the true strains were same. The results show that with the same strains and strain rates, the higher the deformation temperature, the easier the recrystallization occurs, and the greater the size of the recrystal grains. And with the same strains and deformation temperatures, the lower the strain rate, the easier the recrystallization occurs, and the greater the proportion and size of the recrystal grains. Keywords:Weathering steel, Deformation temperature, Strain rate, Thermal deformation equation, Recrystallization

Characterization of Hot Deformation Behavior of TC18 Titanium Alloy

2015 ◽  
Vol 815 ◽  
pp. 263-267
Author(s):  
Qing Chuan Yang ◽  
Ke Hui Qiu ◽  
Ren Gui Jiang ◽  
De Ming Huang ◽  
Hua Lin He
Keyword(s):  
Titanium Alloy ◽  
Strain Rate ◽  
Deformation Mechanism ◽  
Hot Deformation ◽  
Deformation Temperature ◽  
True Strain ◽  
Peak Stress ◽  
Compression Tests ◽  
Relationship Model

In this work, hot compression tests on columniform TC18 titanium alloy specimens were performed with a Gleeble® 3500 thermal and mechanical simulator in the temperature range of 820-875 °C and at constant strain rates of 0.01, 0.1 and 1 s−1. Relationship model of true stress versus true strain as well as peak stress versus deformation temperature were established, and microstructural micrographs of TC18 titanium alloy were analyzed. The results showed that the flow stress decreased as the deformation temperature increased or the strain rate decreased. Besides, the deformation resistance at temperature above Tβ (β transus temperature) was obviously lower than that at below Tβ. In addition, flow stresses kept almost constant when it deformed in β region where hot deformation mechanism is DRV, but significant flow softening occurred in α+β region, where deformation mechanism is mainly dominated by DRX. And in α+β region, DRX is prone to occur at a low strain rate, and it is difficult for DRX to occur at high strain rate.

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.

Study on Constitutive Modeling for Large Deformation Behavior of Polyethylene Considering Strain Rate Effect

2013 ◽  
Author(s):  
Sijia Zhong ◽  
Jianfeng Shi ◽  
Jinyang Zheng
Keyword(s):  
Strain Rate ◽  
Large Deformation ◽  
Constitutive Modeling ◽  
Deformation Behavior ◽  
True Strain ◽  
True Stress ◽  
Uniaxial Tensile ◽  
Pipeline System ◽  
Composite Effect ◽  
Time Deformation

Polyethylene (PE) pipes have been applied in transportation of key energy medium such as natural gas in the past decades. The mechanical property of PE is of great importance for better design and safer application of PE pipeline system. The large deformation behavior is a key character of PE, not only for its significant strain rate sensitivity, but also for localized necking process after yielding. In this paper, a new constitutive modeling method was proposed to charaterize the rate-denpendent large deformation behavior of PE, in which the true stress is regarded as a function of true stain and true strain rate alone. Uniaxial tensile tests of PE were conducted under various cross-head speeds, and a digital camera was used to record the real-time deformation of specimens. By separating the composite effect into respective effect of local true strain and strain rate on the local true stress in the necking region, a phenomenological model for describing the rate-dependent deformation behavior under uniaxial tension was ealstablished. Model results were validated and found in good agreement with experimental data.

Hot Compression Deformation Behavior of Spray-Formed AlSn20Cu Alloy

2021 ◽  
Vol 1035 ◽  
pp. 189-197
Author(s):  
Bao Ying Li ◽  
Bao Hong Zhu
Keyword(s):  
Constitutive Equation ◽  
Strain Rate ◽  
Deformation Behavior ◽  
Deformation Temperature ◽  
Phase Distribution ◽  
True Stress ◽  
Hot Compression ◽  
Test Machine ◽  
Hot Compression Deformation ◽  
Compression Deformation

The hot deformation behavior of spray-formed AlSn20Cu alloy during hot compression deformation was studied, and the constitutive equation of AlSn20Cu alloy was established. The samples of spray-formed AlSn20Cu alloy were compressed on Gleeble-3500 thermal simulation test machine. The error of the true stress caused by adiabatic heating effect in the experiment was corrected. The constitutive equation of spray-formed AlSn20Cu alloy could be represented by Zener-Hollomon parameter in a hyperbolic sine function. The results showed that the deformation temperatures and strain rates had a notable effect on the true stress of the alloy. At the identical deformation temperature, the true stress increased with the increase of strain rate. When the strain rate was constant, the stress decreased with the increase of deformation temperature. After hot compression deformation, the tin phase was elongated along the direction perpendicular to the compression axis with short strips and blocks. With the increase of deformation temperature and the decrease of strain rate, Sn phase distribution became more homogeneous.

scholarly journals Hot Deformation Process Analysis and Modelling of X153CrMoV12 Steel

Metals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1125 ◽  
Author(s):  
Michal Krbaťa ◽  
Maroš Eckert ◽  
Daniel Križan ◽  
Igor Barényi ◽  
Ivana Mikušová
Keyword(s):  
Hot Deformation ◽  
Process Analysis ◽  
True Strain ◽  
Peak Stress ◽  
High Strength ◽  
True Stress ◽  
Point Of View ◽  
Plastic Behavior ◽  
Hollomon Parameter ◽  
Wide Range

Analysis of the high temperature plastic behavior of high-strength steel X153CrMoV12 was developed in the temperature range of 800–1200 °C and the deformation rate in the range of 0.001–10 s−1 to the maximum value of the true strain 0.9%. Microstructural changes were observed using light optical microscopy (LOM) as well as atomic force microscopy (AFM). The effect of hot deformation temperature on true stress, peak stress and true strain was evaluated from the respective flow curves. Based on these results, steel transformation was discussed from the dynamic recovery and recrystallization point of view. Furthermore, a present model, taking into account the Zener–Hollomon parameter, was developed to predict the true stress and strain over a wide range of temperatures and strain rates. Using constitutive equations, material parameters and activation energy were derived, which can be subsequently applied to other models related to hot deformation behavior of selected tool steels. The experimental data were compassed to the ones obtained by the predictive model with the correlation coefficient R = 0.98267. These results demonstrate an appropriate applicability of the model for experimental materials in hot deformation applications.

Hot Deformation Behaviors and Microstructure Evolution of SiCp/Al Composites

2016 ◽  
Vol 849 ◽  
pp. 430-435 ◽  
Author(s):  
Shi Ming Hao ◽  
Jing Pei Xie ◽  
Li Ben Li ◽  
Ai Qin Wang ◽  
Wen Yan Wang ◽  
...  
Keyword(s):  
Strain Rate ◽  
Structural Changes ◽  
True Strain ◽  
Peak Stress ◽  
Small Strain ◽  
Sensitive Material ◽  
Aluminium Matrix Composite ◽  
Compression Behavior ◽  
High Deformation ◽  
Deformation Behaviors

In order to explore the compressive properties of aluminium matrix composite reinforced with middle content SiC particles, hot compression behavior of 30%SiCp/2024A1 composite was investigated using Gleeble-1500 system at a temperatures range from 350 to 500°C and strain rates from 0.01 to 10 s−1. The associated structural changes were studied by OM, SEM and TEM observations. The results show that the true stress–true strain curves exhibited a peak stress at a small strain (<0.1), after which the flow stresses decreased monotonically until high strains, showing a dynamic flow softening. The stress level decreased with increasing deformation temperature and decreasing strain rate, indicating that the composite is a positive strain rate sensitive material. And therefore there will be a enough time for dynamic recrystallization to complete nucleation and growth at low strain rate and high deformation temperatures.

Mechanical Aspects of Plastic Deformation of Nickel Based Superalloy

2013 ◽  
Vol 592-593 ◽  
pp. 724-727
Author(s):  
Andrzej Nowotnik ◽  
Paweł Rokicki ◽  
Paweł Pędrak ◽  
Slawomir Kotowski ◽  
Jan Sieniawski ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Flow Stress ◽  
Strain Rate ◽  
Deformation Process ◽  
True Strain ◽  
True Stress ◽  
Effect Of Temperature ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Nickel Based Superalloy

Variations of a true stress vs. true strain illustrate behaviour of materials during plastic deformation. Stress-strain relationship is generally evaluated by a torsion, compression and tensile tests. Results of these tests provide crucial information pertaining to the stress values which are necessary to run deformation process at specified temperature and cooling rate. Uniaxial compression tests at temperatures below the γ solvus were conducted on nickel based superalloy CMSX-4, to study the effect of temperature and strain rate on its flow stress. On the basis of received flow stress values activation energy of a high-temperature deformation process was estimated. Mathematical dependences (σpl -T i σpl - ἐ) and compression data were used to determine material constants. These constants allow to derive a formula that describes the relationship between strain rate, deformation temperature and true stress.

Hot Deformation Behavior and Microstructure Evolution of a DC Cast Hypereutectic Al-Si Alloy

2012 ◽  
Vol 151 ◽  
pp. 332-336
Author(s):  
Ke Zhun He ◽  
Fu Xiao Yu ◽  
Da Zhi Zhao ◽  
Liang Zuo
Keyword(s):  
Strain Rate ◽  
Microstructure Evolution ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
Deformation Temperature ◽  
Peak Stress ◽  
Strain Rate Range ◽  
Hot Deformation Behavior ◽  
Strong Function ◽  
Primary Si

The hot deformation behavior and microstructure evolution of a DC cast hypereutectic Al-Si alloy was studied in the temperature range of 400-500 °C and strain rate range of 0.001-1 s-1. The results show that the as-cast microstructure of the alloy consists of polygonal primary Si particles and α-aluminum dendritic halos with Al-Si eutectics and intermetallic compounds segregated into the interdendritic regions. The flow stress of the alloy is a strong function of temperature and strain rate, and the peak stress is increased with the decrease of deformation temperature and the increase of strain rate. All the true stress-true stain curves in the experiments exhibit dynamic softening. The fracture frequency of primary Si particle is decreased with the increase of deformation temperature and the decrease of strain rate. The dynamic flow softening is mainly as a result of dynamic recrystallization.

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.

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