Modeling and Finite Element Analysis for the Dynamic Recrystallization Behavior of Ti-5Al-5Mo-5V-3Cr-1Zr Near β Titanium Alloy During Hot Deformation

2018 ◽  
Vol 37 (5) ◽  
pp. 445-454 ◽  
Author(s):  
Ya-ping Lv ◽  
Shao-jun Li ◽  
Xiao-yong Zhang ◽  
Zhi-you Li ◽  
Ke-chao Zhou
Keyword(s):  
Finite Element ◽  
Titanium Alloy ◽  
Dynamic Recrystallization ◽  
Hot Deformation ◽  
Critical Strain ◽  
Volume Fraction ◽  
Peak Strain ◽  
Simulation Experiments ◽  
Relationship Of ◽  
The Relationship

AbstractEvolution for the dynamic recrystallization (DRX) volume fraction of Ti-5Al-5Mo-5V-3Cr-1Zr near β titanium alloy during hot deformation was characterized by using the Johnson–Mehl–Avrami–Kolmogorov (JMAK) equation. To determine the equation parameters, a series of thermal simulation experiments at the temperature of 1023–1098 K and strain rate of 0.001–1 s‒1 to the true strain of 0.7 were conducted to obtain the essential data about stress σ and strain ε. By further transforming the relationship of σ versus ε into the relationship of strain hardening rate dσ/dε versus σ, two characteristic strains at the beginning of DRX (critical strain εc) and at the peak stress (peak strain εp) were identified from the dσ/dε-σ curves. Sequentially, the parameters in the JMAK equation were determined from the linear fitting of the different relationships among critical strain εc, peak strain εp and deformation conditions (including temperature T, strain rate $\dot \varepsilon $ and strain ε). The as-obtained JMAK equation was expressed as XDRX=1-exp[-0.0053((ε-εc)/εc)2.1], where εc=0.6053εp and εp=0.0031$\dot \varepsilon $0.0081exp(28,781/RT). Finally, the JMAK equation was implanted into finite element program to simulate the hot compression of thermal simulation experiments. The simulation predictions and experimental results about the DRX volume fraction distribution showed a good consistency.

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.

scholarly journals CONSTITUTIVE MODELING OF DYNAMIC RECRYSTALLIZATION AND PRECIPITATION BEHAVIOR OF Nb AND Ti OF Q1030 HIGH STRENGTH STEEL

2020 ◽  
Vol 1 (1) ◽  
pp. 01-05
Author(s):  
J.J. Wang ◽  
Y.L. Kang ◽  
Y.L. Liu ◽  
H Yu
Keyword(s):  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Hot Deformation ◽  
High Strength Steel ◽  
Critical Strain ◽  
High Strength ◽  
Second Phase ◽  
Peak Strain ◽  
Precipitation Behavior ◽  
Deformation Equation

The thermal deformation and precipitation behavior at 900-1100℃ and strain rate of 0.1-5s-1 were studied by Gleeble-3800 thermal simulator of Q1030 high strength steel. The activation energy of hot deformation in austenite region was determined by regression method, and the hot deformation equation of the Q1030 high strength steel was established. The critical strain and peak strain of dynamic recrystallization were predicted accurately by fitting the inflection point with cubic polynomial of curve of Q1030 high strength steel, and relationship between critical strain and Z parameter was established. Finally, the precipitation behavior of Nb and Ti particles during low strain rate deformation was studied, the results show that the precipitated phases in steel are rectangular TiN, quadratic (Nb, Ti) (C, N) carbonitride, elliptical (Nb, Ti) C carbide and NbC. Thermodynamic calculation shows that the order of precipitation of the second phase in steel is TiN, TiC, NbC and NbN.

scholarly journals Effect of Trace Magnesium Additions on the Dynamic Recrystallization in Cast Alloy 825 after One-Hit Hot-Deformation

Metals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 36
Author(s):  
Munir Al-Saadi ◽  
Wangzhong Mu ◽  
Christopher N. Hulme-Smith ◽  
Fredrik Sandberg ◽  
Pär G. Jönsson
Keyword(s):  
Service Life ◽  
Dynamic Recrystallization ◽  
Hot Deformation ◽  
Cast Alloy ◽  
True Strain ◽  
Peak Strain ◽  
Compression Tests ◽  
Electron Backscattered Diffraction ◽  
Hollomon Parameter ◽  
Test Conditions

Alloy 825 is widely used in several industries, but its useful service life is limited by both mechanical properties and corrosion resistance. The current work explores the effect of the addition of magnesium on the recrystallization and mechanical behavior of alloy 825 under hot compression. Compression tests were performed under conditions representative of typical forming processes: temperatures between 1100 and 1250 °C and at strain rates of 0.1–10 s−1 to a true strain of 0.7. Microstructural evolution was characterized by electron backscattered diffraction. Dynamic recrystallization was found to be more prevalent under all test conditions in samples containing magnesium, but not in all cases of conventional alloy 825. The texture direction ⟨101⟩ was the dominant orientation parallel to the longitudinal direction of casting (also the direction in which the samples were compressed) in samples that contained magnesium under all test conditions, but not in any sample that did not contain magnesium. For all deformation conditions, the peak stress was approximately 10% lower in material with the addition of magnesium. Furthermore, the differences in the peak strain between different temperatures are approximately 85% smaller if magnesium is present. The average activation energy for hot deformation was calculated to be 430 kJ mol−1 with the addition of magnesium and 450 kJ mol−1 without magnesium. The average size of dynamically recrystallized grains in both alloys showed a power law relation with the Zener–Hollomon parameter, DD~Z−n, and the exponent of value, n, is found to be 0.12. These results can be used to design optimized compositions and thermomechanical treatments of alloy 825 to maximize the useful service life under current service conditions. No experiments were conducted to investigate the effects of such changes on the service life and such experiments should now be performed.

Study on Dynamic Recrystallization Behavior in Deformed Austenite of 52100 Steel by Using JMAK-Model

2013 ◽  
Vol 275-277 ◽  
pp. 1833-1837
Author(s):  
Ke Lu Wang ◽  
Shi Qiang Lu ◽  
Xin Li ◽  
Xian Juan Dong
Keyword(s):  
Grain Size ◽  
Dynamic Recrystallization ◽  
Hot Deformation ◽  
Volume Fraction ◽  
True Strain ◽  
Strain And Strain Rate ◽  
Average Grain Size ◽  
Dynamic Recrystallization Behavior ◽  
Simulation And Experiment ◽  
Good Agreement

A Johnson-Mehl-Avrami-Kolmogorov (JMAK)-model was established for dynamic recrystallization in hot deformation process of 52100 steel. The effects of hot deformation temperature, true strain and strain rate on the microstructural evolution of the steel were physically studied by using Gleeble-1500 thermo-mechanical simulator and the experimental results were used for validation of the JMAK-model. Through simulation and experiment, it is found that the predicted results of DRX volume fraction, DRX grain size and average grain size are in good agreement with the experimental ones.

Characteristics of Dynamic Recrystallization during Hot Deformation for High Nitrogen Stainless Steels

2012 ◽  
Vol 715-716 ◽  
pp. 115-121
Author(s):  
Hai Wen Luo ◽  
Xu Dong Fang ◽  
Rui Zhen Wang ◽  
Zhan Yin Diao
Keyword(s):  
Dynamic Recrystallization ◽  
Stainless Steels ◽  
Hot Deformation ◽  
Strain Rates ◽  
Peak Strain ◽  
High Nitrogen ◽  
Flow Curves ◽  
Grain Sizes ◽  
Nitrogen Contents ◽  
High Nitrogen Stainless Steel

Dynamic recrystallization was studied for the stainless steels with nitrogen contents of 0.56% to 1.08% during hot deformation at temperatures of 900~1200 with strain rates ranging from 0.003 to 42 s-1. It was found that flow stress could increase remarkably with increasing nitrogen content. Flow curves during the deformation by 0.1~42/s at temperatures of 900~1200°C show a single peak, indicating the occurrence of dynamic recrystallization during deformation. The peak strain seems to decrease with increasing N content, suggesting that higher content of N facilitates dynamic recrystallization. The quenched microstructures were analyzed by optical microscopy, EBSD and TEM. The recrystallized grain sizes on the quenched specimens were measured and its dependence on temperature and strain rate was analyzed. At high temperature, continuously dynamically recrystallized microstructures were observed; whilst at low temperature, necklace-like partially recrystallized microstructures were found. Key words: High nitrogen stainless steel; dynamic recrystallization; stress-strain curves

Numerical Simulation of Riveting Process

2010 ◽  
Vol 34-35 ◽  
pp. 641-645
Author(s):  
Hong Shuang Zhang
Keyword(s):  
Numerical Simulation ◽  
Finite Element Method ◽  
Residual Stress ◽  
Finite Element ◽  
Process Parameters ◽  
Static Method ◽  
Riveting Process ◽  
Relationship Of ◽  
The Relationship ◽  
Element Method

In order to fully understanding the distribution of residual stress after riveting and the relationship between residual stress and riveting process parameters during riveting, Finite Element Method was used to establish a riveting model. Quasi-static method to solve the convergence difficulties was adopted in riveting process. The riveting process was divided into six stages according to the stress versus time curves. The relationship of residual stress with rivet length and rivet hole clearance were established. The results show numerical simulation is effective for riveting process and can make a construction for the practical riveting.

Simulation of hot high-speed yielding of intermetallic titanium alloy VTI-4 under conditions of high-speed loading

2020 ◽  
Vol 0 (12) ◽  
pp. 10-16
Author(s):  
V.V. Avtaev ◽  
◽  
D. V. Grinevich ◽  
A. V. Zavodov
Keyword(s):  
Finite Element ◽  
Titanium Alloy ◽  
Strain Rate ◽  
Finite Element Simulation ◽  
Modulus Of Elasticity ◽  
High Speed ◽  
Residual Deformation ◽  
Test Results ◽  
Element Simulation ◽  
The Relationship

Yielding tests of VTI-4 alloy specimens have been carried out at temperature 1010 °C under conditions of high-speed loading. Based on the test results the modulus of elasticity as well as axial and radial residual deformation values in the end and central zones for each loading stage were determined. Fitting criteria for finite element simulation and the experiment are proposed with tracing VTI-4 alloy diagram deformation at temperature 1010 °C and strain rate of 2.5 sec–1. As a result of finite element simulation the relationship between the material structures obtained during high-speed yielding and the deflected modes in different zones was determined.

scholarly journals High-Temperature Deformation Behavior and Microstructural Characterization of Ti-35421 Titanium Alloy

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3623 ◽  
Author(s):  
Danying Zhou ◽  
Hua Gao ◽  
Yanhua Guo ◽  
Ying Wang ◽  
Yuecheng Dong ◽  
...  
Keyword(s):  
Titanium Alloy ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
Deformation Temperature ◽  
Phase Region ◽  
Temperature Deformation ◽  
Β Phase ◽  
Α Phase

A self-designed Ti-35421 (Ti-3Al-5Mo-4Cr-2Zr-1Fe wt%) titanium alloy is a new type of low-cost high strength titanium alloy. In order to understand the hot deformation behavior of Ti-35421 alloy, isothermal compression tests were carried out under a deformation temperature range of 750–930 °C with a strain rate range of 0.01–10 s−1 in this study. Electron backscatter diffraction (EBSD) was used to characterize the microstructure prior to and post hot deformation. The results show that the stress–strain curves have obvious yielding behavior at a high strain rate (>0.1 s−1). As the deformation temperature increases and the strain rate decreases, the α phase content gradually decreases in the α + β phase region. Meanwhile, spheroidization and precipitation of α phase are prone to occur in the α + β phase region. From the EBSD analysis, the volume fraction of recrystallized grains was very low, so dynamic recovery (DRV) is the dominant deformation mechanism of Ti-35421 alloy. In addition to DRV, Ti-35421 alloy is more likely to occur in continuous dynamic recrystallization (CDRX) than discontinuous dynamic recrystallization (DDRX).

The identification of dynamic recrystallization and constitutive modeling during hot deformation of Ti55511 titanium alloy

2015 ◽  
Vol 84 ◽  
pp. 204-211 ◽  
Author(s):  
Kai Tan ◽  
Jian Li ◽  
Zhijun Guan ◽  
Jiabing Yang ◽  
Jianxun Shu
Keyword(s):  
Titanium Alloy ◽  
Dynamic Recrystallization ◽  
Constitutive Modeling ◽  
Hot Deformation

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.

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