Hot Deformation Behavior and Microstructure Evolution of Extruded 6069 Al Alloy under Tension

2014 ◽  
Vol 670-671 ◽  
pp. 33-36
Author(s):  
Horng Yu Wu ◽  
Ming Chieh Lin ◽  
Feng Jun Zhu ◽  
Cheng Tao Wu ◽  
Ching Hao Liao ◽  
...  
Keyword(s):  
Dynamic Recovery ◽  
Flow Behavior ◽  
True Strain ◽  
Peak Stress ◽  
Tensile Tests ◽  
Al Alloy ◽  
Strain Rates ◽  
Flow Curves ◽  
Softening Mechanism ◽  
Dynamic Softening

The flow behavior and associated microstructural changes of wrought 6069 Al alloy deformed in tension were analyzed in this work. Tensile tests were conducted on an extruded tube with a thickness of 1.6 mm in the temperature range of 300–500 oC, with initial strain rates from 0.001 to 0.1 s-1. The true stress–true strain curves exhibited a peak stress at a critical strain. The overall level of the flow curve increased when the strain rate was increased and/or the temperature was decreased. The flow curves exhibited a typical flow behavior with dynamic softening and showed that the softening degree after reaching the peak stress was dependent on the deformation conditions. This could be related to the softening mechanism. The main softening mechanism of the alloy was dynamic recovery (DRV) at low temperatures; dynamic recrystallization (DRX) occurred as deformed at high temperatures.

A Mathematical Description for the Stress-Strain Behavior of Annealed 2 1/4 Cr-1 Mo Steel

1976 ◽  
Vol 98 (2) ◽  
pp. 118-125 ◽  
Author(s):  
R. L. Klueh ◽  
T. L. Hebble
Keyword(s):  
Mathematical Description ◽  
Flow Behavior ◽  
True Strain ◽  
Empirical Relationship ◽  
Tensile Tests ◽  
Strain Rates ◽  
Strain Behavior ◽  
Test Conditions ◽  
Wide Range ◽  
Strain Data

We have conducted a detailed series of tensile tests on one heat of annealed 2 1/4 Cr-1 Mo steel over the range 25 to 593°C (75 to 1100°F) and at nominal strain rates of 0.4, 0.04, 0.004, and 0.0004/min. To determine an empirical relationship to represent the flow behavior, we fitted the true-stress true-strain data from these tests to several proposed models. The models fit were those proposed by Hollomon, Ludwik, Ludwigson, and Voce. From a comparison of the standard error of estimate, the Voce equation was concluded to be the best mathematical description of the data under most test conditions and the best single representation over the wide range of test conditions.

Flow Stress Behavior and Deformation Characteristics of Ti-22Al-25Nb Alloys at Elevated Temperature

2005 ◽  
Vol 475-479 ◽  
pp. 825-828
Author(s):  
Xiao Bo Liang ◽  
Shi Qiong Li ◽  
Yun Jun Cheng ◽  
Jian Wei Zhang
Keyword(s):  
Strain Rate ◽  
Dynamic Recovery ◽  
Orthorhombic Phase ◽  
Strain Rates ◽  
Beta Transus ◽  
Compression Tests ◽  
Flow Curves ◽  
Temperature Range ◽  
Softening Mechanism ◽  
Yield Phenomena

The characteristics of deformation of an orthorhombic phase based alloy, Ti-22Al-25Nb (at%), have been studied by hot compression tests in the temperature range of 940-1150°C with the strain rates of 0.01s-1 and 0.1s-1. A flow curves typically controlled by dynamic recovery were observed in the temperature range of 1090-1150 °C for the strain rate of 0.01s-1 , while discontinuous yield phenomena was found for the strain rate of 0.1s-1. The dynamic recovery can be identified by the microstructure characteristics of the deformation specimens. At 1060°C, the temperature of beta transus, the flow curves and microstructure exhibited the same deformation charateristics as that above the beta transus. At the subtransus temperature, a long period of flow softening followed by the steady-state flow can be observed. During the hot deformation, the hard phases α2 and O elongated, subboundary produced followed by cusp formation in the elongated α2 and O phases, the equiaxed morphology phases occurred by B2 phase penetrating along the subboundaries. The softening mechanism was discussed.

Research on Hot Deformation Behaviors of 6061 Al Alloy

2021 ◽  
Vol 1032 ◽  
pp. 141-146
Author(s):  
Xiao Yuan Zhang ◽  
Rui Wang ◽  
Xiao Guo Wang
Keyword(s):  
Flow Stress ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Deformation Temperature ◽  
Flow Behavior ◽  
Al Alloy ◽  
Thermal Excitation ◽  
Softening Mechanism ◽  
Dynamic Softening ◽  
6061 Al Alloy

In this paper, the high temperature flow behaviors of 6061 Al alloy was studied by thermal compression experiments. The effects of temperature, strain rate and strain on the microstructure evolution and flow behavior of the alloy were investigated by experiments. The results show that the flow stress of the alloy increases with the increase of strain rate and it decreases with the increase of deformation temperature. The flow curve reaches the dynamic equilibrium under the interaction of work hardening and dynamic softening mechanism. The uprising deformation temperature promotes thermal excitation dynamic recrystallization of deformed microstructure. With the increase of strain, the microstructure of the alloy is transformed from equiaxed crystal morphology to fibrous structure and strain-induced dynamic recrystallization occurs. As strain rate increases, the action time of dynamic softening mechanism for the studied alloy is reduced, resulting in the fraction of dynamic recrystallized structure is reduced and the flow stress increases.

Construction of Flow Stress Constitutive Equation for 3Cr1Mo0.25V Steel

2012 ◽  
Vol 567 ◽  
pp. 244-249
Author(s):  
Yu Hua Zhang ◽  
Guang Yu Tan ◽  
Shu Cai Yang
Keyword(s):  
Flow Stress ◽  
Constitutive Equation ◽  
Dynamic Recovery ◽  
Rate Variation ◽  
Strain Rates ◽  
Compression Tests ◽  
Temperature Range ◽  
Softening Mechanism ◽  
Dynamic Softening ◽  
Increasing Temperature

The flow stress change of 3Cr1Mo0.25V steel was researched in this paper through hot compression tests performed in a temperature range from 800 to 900oC and with a strain rate variation from 0.01 to 10s-1. Flow stress constitutive equation was constructed according to true stress-strain curves of 3Cr1Mo0.25V steel. Results indicate that the dynamic recovery is the dynamic softening mechanism of 3Cr1Mo0.25V steel. The flow stress increases with increasing strain rates and decreases with increasing temperature. The rheological behavior of 3Cr1Mo0.25V steel can be characterized by the parameter of Zener-Hollomon in a high temperature range. As for 3Cr1Mo0.25V steel, the activation energy of Q evaluated by the linear regression is about 142.9 kJ/mol.

scholarly journals Dynamic Softening Mechanisms and Microstructure Evolution of TB18 Titanium Alloy during Uniaxial Hot Deformation

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 789
Author(s):  
Qiang Fu ◽  
Wuhua Yuan ◽  
Wei Xiang
Keyword(s):  
Titanium Alloy ◽  
Dynamic Recovery ◽  
True Strain ◽  
Hot Workability ◽  
Compression Tests ◽  
Phase Zone ◽  
Β Phase ◽  
Stability And Instability ◽  
Dynamic Softening ◽  
Transus Temperature

In this study, isothermal compression tests of TB18 titanium alloy were conducted using a Gleeble 3800 thermomechanical simulator for temperatures ranging from 650 to 880 °C and strain rates ranging from 0.001 to 10 s−1, with a constant height reduction of 60%, to investigate the dynamic softening mechanisms and hot workability of TB18 alloy. The results showed that the flow stress significantly decreased with an increasing deformation temperature and decreasing strain rate, which was affected by the competition between work hardening and dynamic softening. The hyperbolic sine Arrhenius-type constitutive equation was established, and the deformation activation energy was calculated to be 303.91 kJ·mol−1 in the (α + β) phase zone and 212.813 kJ·mol−1 in the β phase zone. The processing map constructed at a true strain of 0.9 exhibited stability and instability regions under the tested deformation conditions. The microstructure characteristics demonstrated that in the stability region, the dominant restoration and flow-softening mechanisms were the dynamic recovery of β phase and dynamic globularization of α grains below transus temperature, as well as the dynamic recovery and continuous dynamic recrystallization of β grains above transus temperature. In the instability region, the dynamic softening mechanism was flow localization in the form of a shear band and a deformation band caused by adiabatic heating.

Constitutive Modeling for Elevated Temperature Flow Behavior of ZHMn34-2-2-1 Manganese Brass

2017 ◽  
Vol 872 ◽  
pp. 30-37
Author(s):  
Meng Han Wang ◽  
Kang Wei ◽  
Xiao Juan Li
Keyword(s):  
Constitutive Model ◽  
Strain Rate ◽  
Flow Behavior ◽  
Peak Stress ◽  
Strain Rates ◽  
Hollomon Parameter ◽  
Prediction Ability ◽  
Absolute Relative Error ◽  
Deformation Behaviors ◽  
State Stress

The hot compressive deformation behaviors of ZHMn34-2-2-1 manganese brass are investigated on Thermecmastor-Z thermal simulator over wide processing domain of temperatures (923K-1073K) and strain rates (0.01s-1-10s-1). The true stress-strain curves exhibit a single peak stress, after which the stress monotonously decreases until a steady state stress occurs, indicating a typical dynamic recrystallization. A revised constitutive model coupling flow stress with strain, strain rate and deformation temperature is established with the material constants expressed by polynomial fitting of strain. Moreover, better prediction ability of the constitutive model is achieved by implementation of a simple approach for modified the Zener-Hollomon parameter considering the compensation of strain rate and temperature increment. By comparing the predicted and experimented values, the correlation coefficient and mean absolute relative error are 0.997 and 2.363%, respectively. The quantitative statistical results indicate that the proposed constitutive model can precisely characterize the hot deformation behavior of ZHMn34-2-2-1 manganese brass.

Effect of Hot Deformation Parameters on Flow Behavior and Microstructure of Ti-6Al-4V-0.2O Alloy

2017 ◽  
Vol 898 ◽  
pp. 137-143
Author(s):  
Lin Xiang ◽  
Bin Tang ◽  
Hong Chao Kou ◽  
Jie Shao ◽  
Jin Shan Li
Keyword(s):  
Strain Rate ◽  
Hot Deformation ◽  
Deformation Temperature ◽  
Dynamic Recovery ◽  
Volume Fraction ◽  
Flow Behavior ◽  
Strain Rates ◽  
Compression Tests ◽  
Height Reduction ◽  
Deformation Parameters

Isothermal compression tests were conducted to investigate the effect of hot deformation parameters on flow behavior and microstructure of Ti-6Al-4V-0.2O alloy. The experimental results show that the strain rate and height reduction have little effect on the volume fraction of primary α at a deformation temperature of 860 ̊C. At a deformation temperature of 940 ̊C, the volume fraction of primary α at a high strain rate (10s-1) is about 10% less than that at low strain rates (0.01s-1~1s-1). It may be one of the reasons for the significantly discontinuous yielding phenomenon. Another reason is that the dislocation density decreased suddenly due to the dynamic recovery. With the increasing strain rate and the decreasing deformation temperature, the volume fraction of irregular secondary α increases and lamellar secondary α decreases. And with height reduction increasing, the irregular secondary α increases firstly and then tends to be steady because of dynamic recovery and recrystallization.

Kinetics of Dynamic Recrystallization of 18 Ni Maraging Steels

2016 ◽  
Vol 850 ◽  
pp. 13-20 ◽  
Author(s):  
Ni Li ◽  
Fei Zhao ◽  
Huan Zhang ◽  
Yong Hai Ren
Keyword(s):  
Dynamic Recrystallization ◽  
Peak Stress ◽  
Strain Rates ◽  
Recrystallization Behavior ◽  
Compression Tests ◽  
Flow Curves ◽  
Maraging Steels ◽  
Dynamic Recrystallization Behavior ◽  
Characteristic Values ◽  
Kinetics Of

The dynamic recrystallization behavior of 18 Ni maraging steels was investigated by hot compression tests at temperatures ranging from 900 °C to 1100 °C and strain rates ranging from 0.001 to 1 s-1. Based on the flow curves from the tests, the effects of temperatures and strain rates on the dynamic recrystallization behavior were analyzed. The strain-hardening rates versus stress curves were used to determine to the critical strain, the peak stress (strain), the saturated stress and the steady stress. With the assistance of the process parameters, constitutive equations were obtained and the activation energy was determined to be 413544.96 J/mol. The dependence of the characteristic values on Zener-Hollomon was found. The dynamic recrystallization kinetics model of the tested steels was constructed and the validity was confirmed based on the experimental results.

scholarly journals Hot Deformation Behavior and Processing Maps of Fe-30Mn-0.11C Steel

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1940 ◽  
Author(s):  
Jianmei Kang ◽  
Yuhui Wang ◽  
Zhimeng Wang ◽  
Yiming Zhao ◽  
Yan Peng ◽  
...  
Keyword(s):  
Dynamic Recrystallization ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
True Strain ◽  
Peak Stress ◽  
Strain Rates ◽  
Processing Maps ◽  
Compression Tests ◽  
Hot Deformation Behavior ◽  
High Deformation

Hot deformation behavior of Fe-30Mn-0.11C steel was investigated. Hot compression tests were carried out at various temperatures ranging from 800 °C to 1200 °C and at different strain rates of 0.01 s−1 to 10 s−1. The constitutive equation based on peak stress was established. Hot processing maps at different strains and recrystallization diagrams were also established and analyzed. The results show that dynamic recrystallization easily occur at high deformation temperatures and low strain rates. Safe and unstable zones are determined at the true strain of 0.6 and 0.7, and the hot deformation process parameters of partial dynamic recrystallization of the tested steel are also obtained.

scholarly journals Thermomechanical response of Mg AZ31 at different levels of temperatures and strain rates

2019 ◽  
Vol 304 ◽  
pp. 01025
Author(s):  
Farid Abed ◽  
Wael Abuzaid ◽  
Yomna Morad
Keyword(s):  
True Strain ◽  
Weight Ratio ◽  
High Strength ◽  
Tensile Tests ◽  
Industrial Applications ◽  
Gauge Length ◽  
Image Correlation ◽  
Strain Rates ◽  
Localized Deformation ◽  
The Difference

Magnesium alloys’ mechanical behavior has received increasing attention because of its high strength to weight ratio making them ideal for various industrial applications, such as vehicle components, transportation and aerospace. The objective of this work is to closely investigate the thermo-mechanical properties of magnesium alloy AZ31 at different strain rates and temperatures. Tensile tests are conducted on a 30 mm gauge length MgAZ31 specimens at two quasi-static strain rates (1.11x10−3 s−1 and 0.28 s−1) at a range of temperatures between 25 ºC and 250 ºC. Digital Image Correlation (DIC) system was used to calculate the true strain and provide quantitative assessment of the localized deformation response at high levels of deformation. The stress-strain responses of MgAZ31 show that the yield stress as well as the ultimate stress decreases as temperature increases and strain rate decreases. Moreover, the difference between the yield and ultimate stresses at both strain rates increases rapidly as temperature increases. The material shows a significant increase in ductility as temperature increases while the modulus of elasticity remains independent of change in strain rates.

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