Constitutive Modeling for the Prediction of Peak Stress in Hot Deformation Processing of Al Alloy Based Nanocomposite

2011 ◽  
Vol 328-330 ◽  
pp. 1602-1605 ◽  
Author(s):  
V. Senthilkumar ◽  
A. Balaji Abhishek ◽  
Hafeez Ahamed
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Constitutive Modeling ◽  
Hot Deformation ◽  
Constitutive Models ◽  
Peak Stress ◽  
Percentage Error ◽  
Al Alloy ◽  
Measured Flow ◽  
Deformation Tests

Hot deformation tests were carried out on Al5083 – 2 %(vol) TiC nanocomposite in a temperature range of 250 – 450°C at varying strain rate of 0.01 – 1.0 sec-1. Constitutive models were developed for the prediction of peak flow stress relating strain rate, true stress, temperature and activation energy. The percentage error between measured flow stress and constitutive model values were calculated to analyse the efficacy of the model in the prediction of peak stress. Finally, a window of working of the selected nanocomposite is established for finding out the safer region of working.

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.

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.

scholarly journals Quasi-Static Loading Responses and Constitutive Modeling of Al–Si–Mg alloy

Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 838 ◽  
Author(s):  
Zhenglong Liang ◽  
Qi Zhang
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Flow Behavior ◽  
Peak Stress ◽  
Mg Alloy ◽  
Average Error ◽  
Flow Curves ◽  
Modified Model ◽  
Wide Range ◽  
Measured Flow

The flow behavior of the Al–Si–Mg alloy under uniaxial compression loading was investigated at different strain rates (10−3 s−1, 10−2 s−1,10−1 s−1, 100 s−1) at a wide range of temperatures (573 K, 623 K, 673 K, 723 K, 773 K). The results showed that the peak stress increase with the strain rate and decrease with the increase of temperature. According to the measured flow stress curves, a modified Johnson-Cook (J-C) constitutive model taking strain rate effect on thermo softening into account was proposed to delineate the flow behavior. The comparisons between the measured flow curves and the predicted ones showed them to be very close and the average error is 1.65%. The added experiments were also conducted for validating the modified model, and the predicted data well agreed with the measured flow stress curves. That indicated the modified Johnson-Cook model is reliable and can accurately delineate the flow behavior of Al–Si–Mg alloy.

Experimental Investigation and Constitutive Modeling for Hot Deformation Behavior of 2219 Al-Alloy Microalloyed With Silver

2018 ◽  
Vol 140 (4) ◽  
Author(s):  
Purnendu Kumar Mandal ◽  
P. S. Robi
Keyword(s):  
Flow Stress ◽  
Hot Deformation ◽  
Deformation Temperature ◽  
Peak Flow ◽  
True Strain ◽  
Constitutive Models ◽  
Al Alloy ◽  
Strain Rates ◽  
Compression Tests ◽  
Experimental Values

2219Al and 2219Al + 0.1 wt % Ag alloys were processed by casting route. The hot compression tests were carried out at constant true strain rates and temperatures in the range of 10−3 to 101 s−1 and 300–500 °C, respectively. Flow stress of the alloy decreases with the addition of silver. The flow stress of both alloys increases with the decrease in deformation temperature and the increase in strain rates. Constitutive models correlating the peak flow stress with deformation temperature and strain rates for the two alloys were developed using hyperbolic–sine relationship. The activation energy for hot deformation of 2219 Al alloy decreases with the addition of silver. Comparison of the predicted and experimental values of peak flow stress reveals that 92% of the data could be predicted within a deviation error of ±10% indicating good predictive capability for the developed constitutive relationships.

Evolution of Flow Stress and Microstructure in an Al-Zn-MgSeries Alloy during Hot Deformation

2007 ◽  
Vol 546-549 ◽  
pp. 965-970
Author(s):  
Jian Shen ◽  
Yong Heng ShangGuan ◽  
Xiao Dong Yan
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Hot Deformation ◽  
Elevated Temperatures ◽  
Subgrain Size ◽  
True Strain ◽  
Large Angle ◽  
Peak Stress ◽  
Hollomon Parameter ◽  
Dislocation Generation

Evolution of flow stress and microstructures of an Al-Zn-Mg series alloy during deformation at elevated temperatures and large ranges of strain rates have been investigated by isothermal compression testing on Gleeble 1500 thermomechanical simulator. The results showed that the flow stress exhibited a characteristic of peak stress followed by smoothing out in the imposed strain rate and temperature ranges. The hot deformation of the alloy is a thermally activated process, which is controlled by rate-controlling mechanisms of dislocation generation and dislocation annihilation. The flow stress decreases with the increase of true strain at higher temperature and lower strain rate, indicating that dynamic softening dominates instead of strain hardening during hot deformation of the alloy. Microstructure observation revealed that typical subgrain cluster structures obviously developed in the original elongated grains of the alloy during hot deformation. The subgrain size of the alloy increased with deformation temperature and downturn of strain rate, where the Zener-Hollomon parameter increased. Fine equiaxed recrystallized grains with large-angle grain boundaries developed significantly in the alloy during hot compression at low Z values, implying activation of dynamic recrystallization.

A Modified Peric Model for Al-Mg Alloy Sheet with Rate-Independent Initial Yield Stress at Warm Temperatures

2019 ◽  
Vol 287 ◽  
pp. 3-7
Author(s):  
Yong Zhang ◽  
Qing Zhang ◽  
Yuan Tao Sun ◽  
Xian Rong Qin
Keyword(s):  
Flow Stress ◽  
Plastic Strain ◽  
Strain Rate ◽  
Yield Stress ◽  
Constitutive Models ◽  
Mg Alloy ◽  
Initial Yield Stress ◽  
Initial Yield ◽  
Rate Dependent ◽  
Dependent Flow

The constitutive modeling of aluminum alloy under warm forming conditions generally considers the influence of temperature and strain rate. It has been shown by published flow stress curves of Al-Mg alloy that there is nearly no effect of strain rate on initial yield stress at various temperatures. However, most constitutive models ignored this phenomenon and may lead to inaccurate description. In order to capture the rate-independent initial yield stress, Peric model is modified via introducing plastic strain to multiply the strain rate, for eliminating the effect of strain rate when the plastic strain is zero. Other constitutive models including the Wagoner, modified Hockett–Sherby and Peric are also considered and compared. The results show that the modified Peric model could not only describe the temperature-and rate-dependent flow stress, but also capture the rate-independent initial yield stress, while the Wagoner, modified Hockett–Sherby and Peric model can only describe the temperature-and rate-dependent flow stress. Moreover, the modified Peric model could obtain proper static yield stress more naturally, and this property may have potential applications in rate-dependent simulations.

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.

Analysis of Hot Deformation Dynamics of TC18 Titanium Alloy

2013 ◽  
Vol 747-748 ◽  
pp. 878-884 ◽  
Author(s):  
Qing Rui Wang ◽  
Ai Xue Sha ◽  
Xing Wu Li ◽  
Li Jun Huang
Keyword(s):  
Titanium Alloy ◽  
Phase Transformation ◽  
Flow Stress ◽  
Strain Rate ◽  
Hot Deformation ◽  
Deformation Temperature ◽  
Relationship Model ◽  
Deformation Dynamics ◽  
Deformation Mechanics ◽  
Versus Strain

The effect of strain rate and deformation temperature on flow stress of TC18 titanium alloy was studied through heat simulating tests in 760~960 with temperature interval and the strain rate interval in 0.01~10s-1. Relationship model of flow stress versus strain was established and hot deformation mechanics of TC18 titanium alloy was analyzed. The results show that the flow stress reduces obviously as the deformation temperature increases or the strain rate decreases. Dynamic recovery occurs at high strain rate above phase transformation point, while dynamic recrystallization occurs at low strain rate as well as at the temperature below phase transformation point.

Experimental and Numerical Investigations on Hot Deformation Behavior and Processing Maps for ASS 304 and ASS 316

2018 ◽  
Vol 37 (9-10) ◽  
pp. 873-888 ◽  
Author(s):  
Nitin Kotkunde ◽  
Hansoge Nitin Krishnamurthy ◽  
Swadesh Kumar Singh ◽  
Gangadhar Jella
Keyword(s):  
Experimental Data ◽  
Strain Rate ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
Constitutive Models ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Processing Maps ◽  
Hot Deformation Behavior ◽  
Statistical Measures

AbstractA thorough understanding of hot deformation behavior plays a vital role in determining process parameters of hot working processes. Firstly, uniaxial tensile tests have been performed in the temperature ranges of 150 °C–600 °C and strain rate ranges of 0.0001–0.01s−1 for analyzing the deformation behavior of ASS 304 and ASS 316. The phenomenological-based constitutive models namely modified Fields–Backofen (m-FB) and Khan–Huang–Liang (KHL) have been developed. The prediction capability of these models has been verified with experimental data using various statistical measures. Analysis of statistical measures revealed KHL model has good agreement with experimental flow stress data. Through the flow stresses behavior, the processing maps are established and analyzed according to the dynamic materials model (DMM). In the processing map, the variation of the efficiency of the power dissipation is plotted as a function of temperature and strain rate. The processing maps results have been validated with experimental data.

scholarly journals Hot Deformation Behavior and Mechanistic Understanding of New TF400 Titanium Alloy

Metals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1277 ◽  
Author(s):  
Guoqing Dai ◽  
Yuwen Cui ◽  
Danying Zhou ◽  
Yanhua Guo ◽  
Hui Chang ◽  
...  
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
Strain Rate Range ◽  
Maximum Height ◽  
Compression Behavior ◽  
Plastic Deformation Behavior ◽  
Restoration Mechanism ◽  
Mechanistic Understanding

The isothermal hot compression behavior of new Ti–Fe–B (named as TF400) alloy was investigated in the temperature range of 750–950 °C and strain rate range from 0.01 to 10 s−1 with the maximum height reduction of 60% by using a Gleeble 3800 thermal simulator. By considering the effect of strain via variable material parameters, a modified constitutive model was proposed to accurately predict the flow stress. The predicted results demonstrate that the flow stress decreases with the increase of temperature while it increases as the strain rate increases, in good agreement with the present experimental results. A mechanistic understanding of plastic deformation behavior in the TF400 alloys was developed by inspecting the microstructural characteristics prior to and after deformations. Dynamic recrystallization and dynamic transformation were found to be the dominant restoration mechanism during the hot deformation process.

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