Constitutive Modeling of Dynamic Recrystallization Behavior of GH80A Superalloy

2013 ◽  
Vol 455 ◽  
pp. 71-76
Author(s):  
Hong Ke Wang ◽  
Li Wen Zhang ◽  
Sen Dong Gu ◽  
Qiu Hong Quan ◽  
Wen Fei Shen
Keyword(s):  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Strain Rate Range ◽  
Experimental Results ◽  
Avrami Equation ◽  
Compression Tests ◽  
Stress Strain ◽  
Austenite Grain Size ◽  
Dynamic Recrystallization Behavior ◽  
Strain Model

The dynamic recrystallization (DRX) behavior of GH80A superalloy was investigated by isothermal compression tests on a Gleeble1500 thermomechanical simulator. True stress-strain curves and deformed specimens were obtained at the temperature range of 1273-1473K and the strain rate range of 0.01-5s-1. Experimental results show that the stress-strain curves at low strain rate display a typical DRX characteristic. By regression analysis of experimental results, Materials constant n, activation energy Q and Zener-Hollomon (Z) parameter were determined, and the critical strain model and austenite grain size model for dynamic recrystallization were established as a function of deformation temperature and strain rate. The dynamic recrystallization kinetic model for GH80A was established on the basis of the Avrami equation.

Critical Strain for the Initiation of Dynamic Recrystallization in a Ni-Fe Base Alloy

2004 ◽  
Vol 449-452 ◽  
pp. 577-580
Author(s):  
Young Sang Na ◽  
Young Mok Rhyim ◽  
J.Y. Lee ◽  
Jae Ho Lee
Keyword(s):  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Critical Strain ◽  
Base Alloy ◽  
Strain Rate Range ◽  
Boundary Phase ◽  
Alloy 718 ◽  
Compression Tests ◽  
Temperature Range ◽  
Critical Strains

In order to quantitatively analyze the critical strain for the initiation of dynamic recrystallization in Ni-Fe-based Alloy 718, a series of uniaxial compression tests was conducted in the temperature range 927°C - 1066°C and the strain rate range 5 x 10-4s-1- 5 s-1with varying initial grain size. The critical strains were graphically determined based on one parameter approach and microscopically confirmed. The effect of γ'' (matrix-hardening phase) and δ (grain boundary phase)on the critical strain was simply discussed. The constitutive model for the critical strain of Alloy 718 was constructed using the experimental data obtained from the higher strain rate and the temperature range between 940°C and 1040°C.

scholarly journals A Strain Rate-Dependent Damage Evolution Model for Concrete Based on Experimental Results

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Bin Xu ◽  
Xiaoyan Lei ◽  
P. Wang ◽  
Hui Song
Keyword(s):  
Strain Rate ◽  
Uniaxial Compression ◽  
Damage Evolution ◽  
Damage Model ◽  
Evolution Model ◽  
Experimental Results ◽  
Strain Rates ◽  
Compression Tests ◽  
Stress Strain ◽  
Actual Damage

There are various definitions of damage variables from the existing damage models. The calculated damage value by the current methods still could not well correspond to the actual damage value. Therefore, it is necessary to establish a damage evolution model corresponding to the actual damage evolution. In this paper, a strain rate-sensitive isotropic damage model for plain concrete is proposed to describe its nonlinear behavior. Cyclic uniaxial compression tests were conducted on concrete samples at three strain rates of 10−3s−1, 10−4s−1, and 10−5s−1, respectively, and ultrasonic wave measurements were made at specified strain values during the loading progress. A damage variable was defined using the secant and initial moduli, and concrete damage evolution was then studied using the experimental results of the cyclic uniaxial compression tests conducted at the different strain rates. A viscoelastic stress-strain relationship, which considered the proposed damage evolution model, was presented according to the principles of irreversible thermodynamics. The model results agreed well with the experiment and indicated that the proposed damage evolution model can accurately characterize the development of macroscopic mechanical weakening of concrete. A damage-coupled viscoelastic constitutive relationship of concrete was recommended. It was concluded that the model could not only characterize the stress-strain response of materials under one-dimensional compressive load but also truly reflect the degradation law of the macromechanical properties of materials. The proposed damage model will advance the understanding of the failure process of concrete materials.

scholarly journals Influence of Rare Earth on Dynamic Recrystallization Behavior of As-Cast 30Mn Steel

2018 ◽  
Vol 2018 ◽  
pp. 1-9
Author(s):  
Honghong Yan ◽  
Yong Hu ◽  
Dawen Zhao
Keyword(s):  
Rare Earth ◽  
Dynamic Recrystallization ◽  
Strain Rate Range ◽  
Compression Tests ◽  
Forming Process ◽  
Cast Slab ◽  
Forming Technology ◽  
Alloy Addition ◽  
Dynamic Recrystallization Behavior ◽  
Gleeble 3500

Based on casting-rolling compound forming process, the effect of rare earth on dynamic recrystallization (DRX) of as-cast 30Mn steel was investigated by the single-pass hot compression tests performed using a Gleeble-3500 thermomechanical simulator, and the deformation temperature range was 950°C–1150°C and strain rate range was 0.1–1 s−1. With the assistance of the process parameters, constitutive equations were used to obtain the activation energy and hot working equation. The dynamic recrystallization kinetics models of the tested steel were constructed. The results show that rare earth ferrosilicon alloy addition (0.2%, mass fraction) can delay the onset of DRX significantly and refine the hot deformation microstructures. All of the results indicate that the addition of rare earth into as-cast 30Mn steel is helpful to prepare excellent cast slab for the casting-rolling compound forming technology.

Dynamic Recrystallization Behavior of Mg-Gd-Y-Zr Alloy during Hot Compression

2016 ◽  
Vol 849 ◽  
pp. 181-185 ◽  
Author(s):  
Shi Lun Yu ◽  
Yong Hao Gao ◽  
Chu Ming Liu ◽  
Hong Chao Xiao
Keyword(s):  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Volume Fraction ◽  
Peak Stress ◽  
Critical Conditions ◽  
Recrystallization Behavior ◽  
Compression Tests ◽  
Dynamic Recrystallization Behavior ◽  
Increasing Temperature ◽  
The Cost

Dynamic recrystallization behavior of Mg-8.0Gd-3.0Y-0.5Zr (wt.%) alloy and the critical conditions corresponding to the onset of dynamic recrystallization were investigated using uniaxial compression tests conducted at temperatures ranging from 350 °C to 500 °C and strain rates ranging from 0.001 s-1 to 1 s-1. Results show that increasing temperature and/or decreasing strain rate can enhance the process of dynamic recrystallization of Mg-8.0Gd-3.0Y-0.5Zr alloy and lower the peak stress and corresponding strain. However, decreasing temperature and/or increasing strain rate can promote the occurrence of twin dynamic recrystallization (TDRX) within the original grains at the cost of reducing the total volume fraction of dynamically recrystallized grains in the microstructure. Besides, the critical stress and strain corresponding to the onset of dynamic recrystallization of Mg-8.0Gd-3.0Y-0.5Zr at 400 °C and 0.1 s-1 are 173MPa and 0.13, respectively.

The Dynamic Recrystallization of Hot-Deformed Austenite in a Micro-Alloyed Steel

2012 ◽  
Vol 724 ◽  
pp. 287-290
Author(s):  
Yuan She ◽  
Zhao Hui Zhang ◽  
Jun Yang ◽  
Jian Tao Ju
Keyword(s):  
Dynamic Recrystallization ◽  
Peak Stress ◽  
Controlled Rolling ◽  
Alloyed Steel ◽  
Compression Tests ◽  
Austenite Grain Size ◽  
Alloyed Element ◽  
Deformation Equation ◽  
Dynamic Recrystallization Behavior ◽  
Micro Alloyed Steel

As the dynamic recrystallization (DRX) behavior of hot-deformed austenite is the basis of determining controlled rolling schedule for steel, in the present work, the dynamic recrystallization behavior of austenite of a 0.22%C-1.30%Mn-0.04%Nb micro-alloyed steel was investigated by means of high temperature compression tests on the Thermecmastor-Z simulator. By the analysis of true stress-strain curves at different deformation stages, the hot deformation equation of austenite was established for the steel. As a result, the energy to induce recrystallization of austenite for the steel is 419.1 kJmol-1, as it was influenced by the drag effect of micro-alloyed element Nb in solid solution. The ratio (σc/σp) of critical stress σc (where DRX occurs) to peak stress σp is 0.93 while the ratio (εc/εp) of critical strain εc to peak stress εp is 0.52 for the steel. The austenite grain size of dynamic recrystallization of the micro-alloyed steel is refined by decreasing the deformation temperature and improving the stain rate.

Effect of Deformation Conditions on Dynamic Recrystallization of As-Cast GH625 Alloy

2015 ◽  
Vol 816 ◽  
pp. 620-627
Author(s):  
Hao Yu Wang ◽  
Jian Xin Dong ◽  
Mai Cang Zhang ◽  
Lei Zheng ◽  
Zhi Hao Yao ◽  
...  
Keyword(s):  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Process Design ◽  
Deformation Process ◽  
Strain Rates ◽  
Recrystallization Behavior ◽  
Compression Tests ◽  
Volume Percent ◽  
Dynamic Recrystallization Behavior ◽  
Continuous Recrystallization

High temperature compression tests at a deformation temperature range of 1273K~1473K with various strain rates of 0.01s-1~0.1s-1 on as-cast GH625 alloy were carried out, aiming at the current research status that the deformation process of cogging and the recrystallization behavior of ingot are still in the study. The results indicated that the recrystallization nuclei of ingot formed not only along the original grain boundaries, but also in the interdendrite. Dynamic recrystallization volume percent increased with the increase of temperature and the decrease of strain rate. When the temperature was high and strain rate was low, the dynamic recrystallization behavior of as-cast GH625 alloy was dominated by discontinuous recrystallization. However, when the temperature was low and strain rate was high, continuous recrystallization also existed. These results can provide some reliable experimental support for the cogging process design.

A Study on Dynamic Recrystallization Behaviours of AZ80 Magnesium Alloy

2011 ◽  
Vol 189-193 ◽  
pp. 2847-2850
Author(s):  
Ming Yang ◽  
Yong Shun Yang ◽  
Dong Dong Yang
Keyword(s):  
Magnesium Alloy ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Dimensionless Parameter ◽  
Strain Rate Range ◽  
Avrami Exponent ◽  
Compression Tests ◽  
Rate Range ◽  
Recrystallization Kinetics ◽  
Az80 Magnesium Alloy

Using the compression tests on a Gleeble-1500 thermo-mechanical simulator to study the dynamic recrystallization behaviours of AZ80 magnesium alloy in the temperature range of 593-683K and strain rate range of 0.01-10s-1. By the analysis of the dynamic recrystallization kinetics, the Avrami exponent (m) and the constant (k) have been determined, and they aren’t constant and depend on the dimensionless parameter(Z/A).

Constitutive Relationship and Critical Condition for Dynamic Recrystallization of Inconel 625 during Hot Deformation

2012 ◽  
Vol 538-541 ◽  
pp. 1240-1244 ◽  
Author(s):  
Sheng Li Guo ◽  
De Fu Li ◽  
Zhi Gang Wu
Keyword(s):  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Critical Condition ◽  
Strain Rate Range ◽  
Constitutive Relationship ◽  
Inconel 625 ◽  
Compression Tests ◽  
Order Polynomial ◽  
Strain Hardening Rate ◽  
Good Agreement

Hot compression tests of the commercial Inconel 625 were performed in the temperature range of 950 - 1200 °C and strain rate range of 0.01 - 10 s-1. The constitutive relationship and the critical condition for dynamic recrystallization of Inconel 625 were established. The influence of strain on the flow stress was investigated by considering the effect of the strain on material constants. It was found that a five-order polynomial was suitable to represent the influence of the strain. The stress-strain curves obtained by the proposed constitutive equation showed a good agreement with experimental results. It can be used for the analysis problem of hot forming processes.The critical condition for dynamic recrystallization was obtained by using strain hardening rate. The critical strain increased with temperature decreasing and strain rate increasing. The critical condition for dynamic recrystallization can be expressed as .

scholarly journals Modeling of Dynamic Recrystallization Behavior of As-Extruded AM50 Magnesium Alloy during Hot Compression by a Cellular Automaton Method

Metals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 75
Author(s):  
Dayu Shu ◽  
Jing Wang ◽  
Menghao Jiang ◽  
Gang Chen ◽  
Liwei Lu ◽  
...  
Keyword(s):  
Magnesium Alloy ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Cellular Automaton ◽  
Volume Fraction ◽  
Strain Rate Range ◽  
Dynamic Recrystallization Behavior ◽  
Ca Model ◽  
Cellular Automaton Method ◽  
Experimental Values

The dynamic recrystallization (DRX) behavior of as-extruded AM50 magnesium alloy was modelled and simulated by a cellular automaton (CA) method. Isothermal compression experiments were conducted, and the characteristic parameters in the CA model were obtained by the testing stress–strain flow curves in a wide temperature range of 250–450 °C and strain rate range of 0.001–10 s−1. The flow stress, DRX volume fraction and DRX grain size of the as-extruded AM50 magnesium alloy were predicted by CA simulation. The results showed that the DRX behavior of the studied magnesium alloy was susceptive with the temperature and strain rate; meanwhile, the prediction results were approximate to the experimental values, indicating that the developed CA model can make a confident estimation on the DRX behavior of the as-extruded AM50 magnesium alloy in high temperature conditions.

Mechanical Behavior of Metals in Dynamic Compression

1979 ◽  
Vol 101 (3) ◽  
pp. 238-247 ◽  
Author(s):  
A. J. Holzer ◽  
R. H. Brown
Keyword(s):  
Strain Rate ◽  
Dynamic Compression ◽  
Testing Machine ◽  
Hydraulic Testing ◽  
Strain Rate Range ◽  
Load Cell ◽  
Fast Fourier Transformation ◽  
Compression Tests ◽  
Stress Strain ◽  
High Frequency Response

A technique for the measurement of force and displacement data in metal processing at high rates of deformation is described briefly. Forces are determined by fast Fourier transformation of the signal from a quartz load cell and correction in the frequency domain for dynamic response of the load cell. Displacement is measured by a high frequency response fiber-optic transducer. The force and displacement signals are processed by an on-line computer which enables stress, strain, strain-rate, and other parameters to be determined and plotted rapidly. Results from continuous dynamic compression tests are presented in the form of computer generated stress-strain and stress-strain rate curves for two steels. In the strain rate range 10−3 s−1 to 102 s−1 an hydraulic testing machine is used. In the range 102 s−1 to 104 s−1 a drop forge is used. A discussion of the effects of specimen geometry in compression testing is included.

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