scholarly journals Determination of Constitutive Equation and Thermo–Mechanical Processing Map for Pure Iridium

Metals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1087
Author(s):  
Mi Zhou ◽  
Rui Hu ◽  
Jieren Yang ◽  
Chuanjun Wang ◽  
Ming Wen
Keyword(s):  
Constitutive Equation ◽  
Strain Rate ◽  
Processing Map ◽  
Frictional Coefficient ◽  
Strain Curve ◽  
Strain Rate Range ◽  
Forming Process ◽  
Thermal Compression ◽  
Rate Range ◽  
Temperature Range

Deformation behavior of pure iridium has been studied during thermal compression testing with the help of Gleeble-1500D in the temperature range of 1200 °C~1500 °C and strain rate range of 10−1 s−1~10−2 s−1. Resistance to deformation, microstructural evolution and hot workability of pure iridium have been used to analyze in detail. Frictional coefficient has been used to modify the experimental stress–strain curve of thermal compression test, and it has been found effective in reducing the influence of friction during thermo–mechanical testing. The hyperbolic sine constitutive equation of pure iridium has been established to give a material processing model for numerical simulation. A very high value of activation energy for iridium, 573 KJ/mol, clearly indicates that it is very hard to deform this material. The deformation mechanism of pure iridium is dependent upon temperature as well as strain rate. At low temperature and strain rate (temperature range of 1200 °C~1300 °C and strain rate range of 10−1 s−1~10−2 s−1), dynamic recovery is active while dynamic recrystallization becomes operative as temperature and stain rate are increased. On further increase in temperature and decrease in strain rate (temperature range of 1400 °C~1500 °C and strain rates of 10−2 s−1~10−3 s−1), abnormal grain growth takes place. On the basis of a constitutive model and processing map, suitable forming process parameters (temperature range of 1400 °C~1500 °C and strain rate range of 0.1 s−1~0.05 s−1) for pure iridium have been worked out.

Flow Behavior and Processing Map of Mg-4Al-3Ca-1.5Zn-1Nd-0.2Mn Magnesium Alloy

2014 ◽  
Vol 915-916 ◽  
pp. 588-592
Author(s):  
Gang Chen ◽  
Wei Chen ◽  
Guo Wei Zhang ◽  
Jing Zhai ◽  
Li Ma
Keyword(s):  
Magnesium Alloy ◽  
Strain Rate ◽  
Processing Map ◽  
Flow Behavior ◽  
Strain Rate Range ◽  
Compression Tests ◽  
Rate Range ◽  
Temperature Range ◽  
Optimal Temperature Range ◽  
Flow Stress Data

Compression tests of Mg-4Al-3Ca-1.5Zn-1Nd-0.2Mn Magnesium alloy as-extruded had been performed in the compression temperature range from 200°C to 350°C and the strain rate range from 0.001 s1to 1 s1and the flow stress data obtained from the tests were used to develop the power dissipation map, instability map and processing map. The optimum parameters for hot working of the alloy had been determined. According to the processing maps, the most optimal temperature range is 280°C to 350°C and most optimal strain rate range is 0.001 S-1to 1 S-1.

Flow Behavior and Workability of a Zn-8Cu-0.2Cr Alloy during Hot Deformation

2012 ◽  
Vol 538-541 ◽  
pp. 1257-1261
Author(s):  
Sheng Li Guo ◽  
Peng Du ◽  
Xiao Ping Wu ◽  
De Fu Li
Keyword(s):  
Constitutive Equation ◽  
Strain Rate ◽  
Hot Deformation ◽  
Flow Instability ◽  
Flow Behavior ◽  
Strain Rate Range ◽  
Processing Maps ◽  
Compression Tests ◽  
Rate Range ◽  
Temperature Range

The hot deformation behavior of Zn91.8-Cu8-Cr0.2 (in wt.%) was investigated by means of hot compression tests in the temperature range of 230-380 °C and strain rate range of 0.01 - 10 s-1. The constitutive equation and processing maps were developed. The influence of strain on the flow stress was studied by considering the effect of the strain on material constants. The stress-strain curves obtained by the constitutive equation are in good agreement with experimental results. The proposed constitutive equations can be used for the analysis problem of hot forming processes. The processing maps have exhibited a domain, which is optimum processing window for hot working, in the temperature range of 310 - 380 °C and strain rate range of 0.01-1 s-1 corresponding to the higher efficiency of power dissipation. The large regime of flow instability is observed at high strain rate. The instability regime should be avoided during hot deformation processing.

scholarly journals Hot Deformation Behaviors of the Mg-3Sn-2Al-1Zn Alloy: Investigation on its Constitutive Equation, Processing Map, and Microstructure

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 312 ◽  
Author(s):  
Yuhang Guo ◽  
Yaodong Xuanyuan ◽  
Xuannam Ly ◽  
Sen Yang
Keyword(s):  
Constitutive Equation ◽  
Strain Rate ◽  
Processing Map ◽  
True Strain ◽  
Strain Rate Range ◽  
Hot Working ◽  
Microstructure Observation ◽  
Stability And Instability ◽  
Deformation Behaviors ◽  
Working Parameters

In this work, the Mg-3Sn-2Al-1Zn (TAZ321, wt. %) alloy with excellent high temperature resistance was compressed using a Gleeble-3500 thermo-mechanical simulator at a wide temperature and the strain rate range. The kinetics analyses showed that the dominant deformation mechanism was likely caused by the cross slipping of dislocations. A constitutive equation which expressed the relationship between the flow stress, deformation temperature, and strain rate was established, and the average activation energy Q was calculated to be 172.1 kJ/mol. In order to delineate the stability and instability working domains, as well as obtain the optimum hot working parameters of the alloy, the hot processing maps in accordance with Prassad’s criterion are constructed at the true strain of 0.2, 0.4, 0.6, and 0.8, respectively. Based on the hot processing map and microstructure observation, the optimum hot working parameter was determined to be 350 °C/1 s−1. The continuous fine dynamic recrystallization (CDRX) grains occurred in the optimum deformation zone. The predicted instability domains was identified as T = 200–300 °C, ε ˙ = 10−2–1 s−1, which corresponded to the microstructure of deformation twinning and micro cracks at the intersection of grain boundaries.

The Constitutive Relationship and Processing Map of Hot Deformation in A100 steel

2016 ◽  
Vol 35 (4) ◽  
pp. 399-405 ◽  
Author(s):  
Yongkang Liu ◽  
Zongmei Yin ◽  
Junting Luo ◽  
Zhang Chunxiang ◽  
Yanshu Zhang
Keyword(s):  
Strain Rate ◽  
Type Equation ◽  
Strain Rate Range ◽  
Constitutive Relationship ◽  
Compression Tests ◽  
Rate Range ◽  
Temperature Range ◽  
Average Grain Size ◽  
Strain Data ◽  
Different Strains

AbstractIsothermal compression tests were conducted on A100 steel using a Gleeble 1500 thermal simulator at a temperature range of 900–1,200°C and strain rate range of 0.001–3 s−1. Results show that the A100 steel has higher strength than the Aermet 100 steel at high temperatures. Constant values, such as A, α, and n, and activate energy Q were obtained through the regression processing of the stress–strain data curves under different strains. A set of constitutive equations for A100 steel was proposed by using an Arrhenius-type equation. The optimum processing craft ranges for A100 steel based on the analysis of the hot working diagram and deformation mechanism are as follows: temperature range of 1,000–1,100°C and strain rate range of 0.01–0.1 s−1. The average grain size within this working range is 7–22.5 μm.

Characterization of Hot Deformation Behavior of Zr-4 Alloy in Material Application Area

2012 ◽  
Vol 578 ◽  
pp. 202-205
Author(s):  
Guo Qing Lin
Keyword(s):  
Strain Rate ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
Flow Behavior ◽  
Strain Rate Range ◽  
Processing Maps ◽  
Peak Efficiency ◽  
Hot Deformation Behavior ◽  
Rate Range ◽  
Temperature Range

The hot deformation behavior of Zr-4 alloy was studied in the temperature range 650-900°C and strain rate range 0.005-50s-1 using processing maps. The processing maps revealed three domains: the first occurs in the temperature range 780-820°C and strain rate range 0.005-0.05s-1, and has a peak efficiency of 45% at 790°C and 0.005s-1; the mechanism is the dynamic recrystallization. The second occurs in the temperature range greater than 900°C and strain rate range 0.05-0.8s-1, and has a peak efficiency of 40% at 900°C and 0.5s-1, which are the domains of dynamic recovery. In addition, the instability zones of flow behavior can also be recognized by the maps in the temperature range 650-780°C and strain rate range 0.01-0.1s-1, which should be strictly avoided in the processing of the material. Zr-4 alloy is the material for pressure tube applications in nuclear reactors and has better strength and a lower rate of hydrogen uptake compared to other materials under similar service conditions.

The Flow Stress Feature and Constitutive Equation of 6016 Aluminum Alloy during Hot Compression

2012 ◽  
Vol 538-541 ◽  
pp. 1687-1692
Author(s):  
Ji Xiang Zhang ◽  
Wei Feng ◽  
Hui Wen ◽  
Guo Yin An
Keyword(s):  
Aluminum Alloy ◽  
Flow Stress ◽  
Linear Regression ◽  
Constitutive Equation ◽  
Strain Rate ◽  
Strain Rate Range ◽  
Thermal Simulation ◽  
Hot Compression ◽  
Rate Range ◽  
6016 Aluminum Alloy

The flow stress behavior of 6016 aluminum alloy was investigated on the condition of temperature range from 420°C to 540°C and strain rate range from 0.001s-1to 1s-1based on hot compression experiment on Gleeble-1500 thermal simulation machine. The result shows that the flow stress of 6016 aluminum alloy decreases with the enhancement of temperature and increases with the increase of strain rate. Especially, the flow stress increases tendency becomes obvious when the strain rate greater than 0.1s-1. Based on the results above, a constitutive equation for flow stress of 6016 aluminum alloy when the temperature is above 420°C is obtained by linear regression.

scholarly journals A Novel Computational Method of Processing Map for Ti-6Al-4V Alloy and Corresponding Microstructure Study

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1599 ◽  
Author(s):  
Ming Hu ◽  
Limin Dong ◽  
Zhiqiang Zhang ◽  
Xiaofei Lei ◽  
Rui Yang ◽  
...  
Keyword(s):  
Strain Rate ◽  
Phase Field ◽  
Processing Map ◽  
Strain Rate Range ◽  
Microstructural Feature ◽  
Computational Method ◽  
Flow Localization ◽  
Optimal Domain ◽  
Rate Range ◽  
Β Phase

The Arrhenius-type constitutive equation is mostly used to describe flow behaviors of material. However, no processing map has been constructed directly according to it. In this study, a novel computational method was applied for establishing the processing map for Ti-6Al-4V alloy in the temperature and strain rate range of 800–1050 °C and 0.001–10 s−1, respectively. The processing map can be divided into four domains according to its graphic features. Among the four domains, the optimal domain is in the temperature and strain rate range of 850–925 °C and 0.001–0.1 s−1, where peak efficiency η is 0.54 and the main microstructural evolution is DRX (dynamic recrystallization). When the alloy is processed in the α + β phase field, the temperature and strain rate range of 800–850 °C and 3–10 s−1 should be avoided, where instability parameter ξ is negative and the microstructural feature is flow localization. When the alloy is processed in the β phase field, DRV (dynamic recovery) and slight DRX of β phase is the main microstructural characteristics in the range of 1000–1050 °C and 0.001–0.02 s−1. However, flow localization of β phase is the main microstructural feature in the range of 1000–1050 °C and 1–10 s−1, which should be avoided.

Thermal Deformation Behavior and Critical Conditions of Dynamic Recrystallization of QCr0.8 Alloy

2019 ◽  
Vol 944 ◽  
pp. 38-45
Author(s):  
Shu Yu Yang ◽  
Qiang Song Wang ◽  
Guo Liang Xie ◽  
Dong Mei Liu ◽  
Fang Liu
Keyword(s):  
Constitutive Equation ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Deformation Behavior ◽  
Thermal Deformation ◽  
Processing Map ◽  
Critical Conditions ◽  
Temperature Deformation ◽  
Thermal Compression ◽  
Compression Deformation

In this paper, the flow stresses, the constitutive equation, processing map and the critical conditions of dynamic recrystallization (DRX) of the hot forged QCr0.8 alloy are studied by hot compressive test in the 750-900°C temperature and 0.01-10s-1 strain rate ranges using Gleeble-1500D thermo-mechanical simulator. The compression reduction of thermal compression deformation is 50%. The results show that the thermal deformation temperatures and strain rates have a significant effect on the high temperature deformation behavior of the alloy. The higher the temperature, the smaller the strain rate and the easier the DRX of the alloy is found.The peak stresses of the alloy decreases with the increase of temperature and increases with the increase of the strain rates.The flow stresses during hot deformation can be described by a hyperbolic sine function. The activation energy Q of the thermal compression deformation is determined to be 370.8KJ/mol. The constitutive equation and processing map of the alloy are established. Critical strains of DRX εc are studied by the inflection point characteristic of the lnθ-ε curve of the alloy and the corresponding minimum value of the ∂θ (∂θ)/∂ε-ε curve.

A Study at the Workability of Ultra-High Strength Steel Sheet by Processing Maps on the Basis of DMM

2017 ◽  
Vol 36 (7) ◽  
pp. 657-667 ◽  
Author(s):  
Yu Feng Xia ◽  
Shuai Long ◽  
Tian-Yu Wang ◽  
Jia Zhao
Keyword(s):  
Activation Energy ◽  
Strain Rate ◽  
High Strength Steel ◽  
High Strength ◽  
Strain Rate Range ◽  
Diffusion Activation Energy ◽  
Processing Maps ◽  
Rate Range ◽  
Temperature Range ◽  
Ultra High Strength Steel

AbstractThe hot workability of the ultra-high strength steel BR1500HS has been investigated by processing maps. A series of hot deformation tensile tests were carried out on a Gleeble-3500 thermal simulator in the deformation temperature range of 773–1,223 K and strain rate range of 0.01–10 s–1. The obtained flow stress curves reveal that the peak stress increases with the rising of strain rate and decreases with the rising of temperature. Based on dynamic materials model (DMM), the processing maps at the strains of 0.05, 0.10 and 0.15 were developed, and the optimum hot working conditions were recommended as the temperature range of 1,200–1,223 K and the strain rate range of 0.01–0.1 s–1, where the peak power dissipation efficiency is about 37 % revealing the occurrence of typical dynamic recrystallization (DRX). The main instability defects are deformation twinning and micro-crack occurring mainly at the temperature range of 773–873 K with the strain rate higher than 1 s–1. In order to deeply understand the microstructure mechanisms, the Zener–Hollomon parameter is solved, and then the self-diffusion activation energy is compared with the apparent activation energy Q at different deformation temperatures and strain rates.

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