A New Constitutive Equation to Predict Single Peak Flow Stress Curves

2013 ◽  
Vol 135 (1) ◽  
Author(s):  
E. Shafiei ◽  
R. Ebrahimi
Keyword(s):  
Flow Stress ◽  
Constitutive Equation ◽  
Dynamic Recrystallization ◽  
Single Peak ◽  
Stress Strain ◽  
Characteristic Points ◽  
Stress Curve ◽  
Flow Stress Curve ◽  
State Stress ◽  
Good Agreement

In this study a new constitutive equation, using the extrapolation of dynamic recovery (DRV) flow stress curve and kinetic equation for dynamic recrystallization (DRX), has been developed. This model is expressed in terms of characteristic points such as critical stress, critical strain, DRX steady state stress, and DRV saturation stress. Moreover, this analysis was done for the stress-strain curves under hot working condition for Ti-IF steel, but it is not dependent on the type of material and can be extended for any condition that a single peak dynamic recrystallization occurs. The results indicate that the stress-strain curves predicted by this model are in a good agreement with experimentally measured ones at all deformation conditions.

scholarly journals Prediction of Flow Stress Curve of Metallic Foam using Compressible Constitutive Equation

2018 ◽  
Vol 1063 ◽  
pp. 012159
Author(s):  
Hiroshi Utsunomiya ◽  
Yohei Noguchi ◽  
Woo-Young Kim ◽  
R. Matsumoto
Keyword(s):  
Flow Stress ◽  
Constitutive Equation ◽  
Metallic Foam ◽  
Stress Curve ◽  
Flow Stress Curve

Modeling the flow stress for single peak dynamic recrystallization

2009 ◽  
Vol 30 (6) ◽  
pp. 1939-1943 ◽  
Author(s):  
Zhipeng Zeng ◽  
Stefan Jonsson ◽  
Hans Jørgen Roven ◽  
Yanshu Zhang
Keyword(s):  
Flow Stress ◽  
Dynamic Recrystallization ◽  
Single Peak

A Flow Stress Model for AZ31B Considering Recrystallization Kinetics

2013 ◽  
Vol 753-755 ◽  
pp. 913-917 ◽  
Author(s):  
Long Ping Shen ◽  
Zhao Yang Jin ◽  
Juan Liu
Keyword(s):  
Flow Stress ◽  
Deformation Condition ◽  
Avrami Equation ◽  
Stress Model ◽  
Softening Mechanism ◽  
Magnesium Alloy Az31b ◽  
Stress Curve ◽  
Measured Flow ◽  
Flow Stress Curve ◽  
Flow Stress Model

According to the different softening mechanism, a flow stress model for magnesium alloy AZ31B is established. At the stage of dynamic recovery (DRV), the effect of work hardening (WH) and DRV on flow stress is described by dislocation evolution model. At the stage of dynamic recrystallization (DRX), the flow stress curve is obtained from Avrami equation denoting the recryatallization kinetics. Model parameter and its dependence on deformation condition are identified by the measured flow stress curve. The calculated curves agree well with the measured ones, which demonstrate the availability of the method.

Determination of Uniaxial Flow Stress Curve Using Aero-Bulge Test for Very Thin Copper Sheet

2011 ◽  
Vol 264-265 ◽  
pp. 608-613 ◽  
Author(s):  
J. Kim ◽  
J. Suh ◽  
Hartmut Hoffmann ◽  
Roland Golle
Keyword(s):  
Flow Stress ◽  
Large Strain ◽  
Material Behavior ◽  
Uniaxial Tensile ◽  
Bulge Test ◽  
Copper Sheet ◽  
Stress Curve ◽  
Flow Stress Curve ◽  
Biaxial Flow

Determination of the flow stress curve is an important step for precisely describing material behavior in Finite Element simulations. The flow stress curve is generally determined by taking a uniaxial tensile test as a standard. In the case of very thin sheet, since the fracture is generated at a low strain, there is not enough uniaxial data obtained to be applied in the FE simulation. The reason for this is that charactering plastic deformation at a large strain values by extrapolating a flow stress curve which is based on insufficient measurement data is highly susceptible to error. Bulge test is useful method for determining the equivalent biaxial flow stress curve up to a large strain. In this paper, the biaxial flow stresses curve for very thin copper sheet with thickness 35 and 50 μm were determined using the aero-bulge test. A new empirical model was derived for the estimation of the sheet thickness at the pole. After the compatibility between uniaxial and biaxial flow stresses was verified, the uniaxial flow stress curve was determined from the aero-bulge test using reverse engineering. The methodology of extrapolation of the flow stress curve at a large strain was finally proposed for application in FE simulations.

Study on the Creep Properties and Microstructures of EW75 Alloy

2014 ◽  
Vol 633-634 ◽  
pp. 133-136
Author(s):  
Yong Jun Li ◽  
Xing Gang Li ◽  
Kui Zhang
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Deformation Rate ◽  
Deformation Temperature ◽  
Shear Fracture ◽  
Solute Drag ◽  
Dislocation Slip ◽  
Creep Properties ◽  
Stress Curve ◽  
Flow Stress Curve

The creep properties and microstructures of the aged (220°C, 6h) EW75 magnesium alloy at different temperature and of stress conditions were studied. The experimental results show that, the deformation temperature and deformation rate have visible influence on flow stress curve of EW75 alloy. When the deformation temperature was constant, the stress rheological increases with the strain rate increasing. When the deformation rate was constant, the flow stress decreases with the deformation temperature increasing. When the deformation temperature was low or deformation rate was quickly, the shear fracture was along 45° direction. At low temperature and high strain rate conditions, the recrystallization of EW75 alloy was not obvious. When raising the temperature and decreasing deformation rate, the dynamic recrystallization ratio was improved markedly. The generating and moving of dislocations during deformation were main factor to determine the final microstructures. At 100MPa, 200°C conditions, the creep rate control mechanism of EW75 alloy was dislocation slip by solute drag. Precipitation phases coarsening was the main reason that the creep properties of EW75 alloy decreased.

scholarly journals Microstructure Evaluation and Constitutive Modeling of AISI-1045 Steel for Flow Stress Prediction under Hot Working Conditions

Symmetry ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 782
Author(s):  
Mohanraj Murugesan ◽  
Muhammad Sajjad ◽  
Dong Won Jung
Keyword(s):  
Flow Stress ◽  
Constitutive Equation ◽  
Constitutive Model ◽  
Stress Strain ◽  
Strain Data ◽  
Aisi 1045 Steel ◽  
Aisi 1045 ◽  
Stress Prediction ◽  
1045 Steel ◽  
Actual Test

In the field of engineering, automobile and aerospace components are manufactured based on the desired applications from the metal forming process. For producing better quality of both symmetry and asymmetry mechanical parts, understanding the material deformation and analytical representation of the material ductility behavior for the working material is necessary as the forming procedures carried out mostly in the warm processing conditions. In this work, the hot tensile test flow stress-strain data were utilized to construct the constitutive equation for describing AISI-1045 steel material hot deformation behavior, and the test conditions, such as deformation temperatures and strain rates were 750–950 ° C and 0.05–1.0 s − 1 , respectively. The surface morphology and elemental identification analysis were performed using the field emission scanning electron microscopy (FESEM) coupled with the energy-dispersive X-ray spectroscopy (EDS) mapping setup. In this work, the Arrhenius-type constitutive equation, including the strain compensation, was used to formulate the flow stress prediction model for capturing the material behavior. Besides, the Zener-Hollomon parameter was altered, employing incorporating the effect of strain rate and strain on the flow stress. The empirical model approach was employed to estimate the material model constants from the constitutive equation using the actual test measurements. The population metrics such as coefficient of determination ( R 2 ), sample standard deviation of the error (SSD), standard error of the regression (SER), coefficient of residual variation (CRV), and average absolute relative error (AARE) was employed to confirm the predictability of the proposed models. The computed results are discussed in detail, using numerical and graphical verification’s. From the graphical comparison, the flow stress-strain data achieved from the proposed constitutive model are in good agreement with the actual test measurements. The constitutive model prediction accuracy is found to be improved, like the prediction error range from 3.678% to 2.984%. This evidence proves to be feasible as the newly developed model displayed a significant improvement against the experimental observations.

Compressive Deformation of Cast AM60B Mg Alloy at Elevated Temperatures

2007 ◽  
Vol 546-549 ◽  
pp. 271-274
Author(s):  
Han Xue Cao ◽  
Si Yuan Long ◽  
Hui Min Liao
Keyword(s):  
Constitutive Equation ◽  
Compression Ratio ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Mg Alloy ◽  
Compressive Deformation ◽  
Stress Strain ◽  
Empirical Results ◽  
Experimental Findings ◽  
Good Agreement

The deformability of cast AM60B Mg alloy is investigated by compressing AM60B cast ingots at elevated temperatures. The empirical results show that cast AM60B Mg alloy was brittle at room temperature and prone to cracking during compression, however at the temperatures ranging from 573 to 673K, excellent deformability is demonstrated with around 70% compression ratio. The compressive deformation constitutive equation for AM60B Mg alloy at elevated temperatures was established. The stress-strain relationships predicted at elevated temperatures show good agreement with experimental findings.

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