scholarly journals Phase transformation and evolution of dislocation structure in the β phase of Ti-17 alloy during hot deformation

2020 ◽  
Vol 321 ◽  
pp. 13006
Author(s):  
K. Yamanaka ◽  
M. Mori ◽  
H. Matsumoto ◽  
A. Chiba
Keyword(s):  
Phase Transformation ◽  
Hot Deformation ◽  
Dynamic Recovery ◽  
Flow Behavior ◽  
True Strain ◽  
Recovery Process ◽  
Deformation Condition ◽  
Compression Tests ◽  
Β Phase ◽  
Dynamic Phase

The hot deformation behavior and microstructural evolution of Ti–5Al–2Sn–2Zr–4Mo–4Cr (Ti-17) alloy in the β-phase field were examined. Hot compression tests were conducted at temperatures ranging from 700 and 1100 °C and strain rates ranging from 10-3 to 1 s-1. The obtained true stress–true strain curves exhibited steady-state flow behavior at temperatures above the β-transus temperature (Tβ ~ 890 °C). The microstructural observations suggested that the dynamic recovery process represents a dominant mechanism for the β-phase of the alloy. In contrast, the flow softening was identified at 700 °C at a strain rate of 10–3 s–1. The formation of fine acicular α microstructures was noticed in such a deformation condition, indicating that dynamic phase transformation can occur in the metastable β-phase during hot deformation. Such a dynamic phase transformation also occurred preferentially at the initial β-grain boundaries as well as sub-boundaries that created within the βmatrix via dynamic recovery. The β-processing conditions were also examined by constructing processing maps based on the dynamic materials model (DMM).

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.

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.

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.

The Constitutive Model for High Temperature Flow Behavior of SiC/6168Al Composite

2015 ◽  
Vol 1089 ◽  
pp. 37-41
Author(s):  
Jiang Wang ◽  
Sheng Li Guo ◽  
Sheng Pu Liu ◽  
Cheng Liu ◽  
Qi Fei Zheng
Keyword(s):  
Constitutive Model ◽  
Hot Deformation ◽  
Flow Behavior ◽  
Type Equation ◽  
Strain Rate Range ◽  
Compression Tests ◽  
Stress Strain ◽  
Hollomon Parameter ◽  
Proposed Model ◽  
Relationship Of

The hot deformation behavior of SiC/6168Al composite was studied by means of hot compression tests in the temperature range of 300-450 °C and strain rate range of 0.01-10 s-1. The constitutive model was developed to predict the stress-strain curves of this composite during hot deformation. This model was established by considering the effect of the strain on material constants calculated by using the Zenter-Hollomon parameter in the hyperbolic Arrhenius-type equation. It was found that the relationship of n, α, Q, lnA and ε could be expressed by a five-order polynomial. The stress-strain curves obtained by this model showed a good agreement with experimental results. The proposed model can accurately describe the hot flow behavior of SiC/6168Al composite, and can be used to numerically analyze the hot forming processes.

Constitutive Equation for 3104 Alloy at High Temperatures in Consideration of Strain

2016 ◽  
Vol 35 (6) ◽  
pp. 599-605 ◽  
Author(s):  
Fuqiang Zhen ◽  
Jianlin Sun ◽  
Jian Li
Keyword(s):  
Hot Deformation ◽  
Flow Behavior ◽  
Temperature Correction ◽  
Strain Rates ◽  
Compression Tests ◽  
Hot Deformation Behavior ◽  
Element Analysis ◽  
Hollomon Parameter ◽  
The Finite Element Analysis ◽  
Effects Of Temperature

AbstractThe flow behavior of 3104 aluminum alloy was investigated at temperatures ranging from 250°C to 500°C, and strain rates from 0.01 to 10 s−1 by isothermal compression tests. The true stress–strain curves were obtained from the measured load–stroke data and then modified by friction and temperature correction. The effects of temperature and strain rate on hot deformation behavior were represented by Zener–Hollomon parameter including Arrhenius term. Additionally, the influence of strain was incorporated considering the effect of strain on material constants. The derived constitution equation was applied to the finite element analysis of hot compression. The results show that the simulated force is consistent with the measured one. Consequently, the developed constitution equation is valid and feasible for numerical simulation in hot deformation process of 3104 alloy.

Hot Deformation Studies of a Low Carbon Steel Containing V

2013 ◽  
Vol 554-557 ◽  
pp. 1224-1231 ◽  
Author(s):  
Cecilia Poletti ◽  
Martina Dikovits ◽  
Javier Ruete
Keyword(s):  
Strain Rate ◽  
Hot Deformation ◽  
Flow Instability ◽  
True Strain ◽  
Low Carbon Steel ◽  
Dynamic Effect ◽  
Rate Sensitivity ◽  
Low Carbon ◽  
Compression Tests ◽  
Deformation Parameters

Low alloyed steels produced by continuous casting are thermomechanically treated to achieve final high mechanical properties, meaning a good combination of strength and toughness. The hot deformation mechanisms of a micro-alloyed steel containing up to 0.1wt% of V is studied by means of hot compression tests using a Gleeble®3800 device. Austenitization of samples is carried out at 1150°C during 2 minutes followed by cooling to the deformation temperature at 1Ks-1in the range of 750 – 1150°C. The studied strain rate range is from 0.01 to 80 s-1and the total true strain achieved is of 0.7. In situ water quenching is applied after the deformation to freeze the microstructure and avoid any post dynamic effect. The Ar3temperature is determined by dilatometry experiments to be 725°C for the used cooling rate. The stress values obtained from the compression tests are evaluated at different strains to determine the strain rate sensitivity and flow instability maps and thus, to predict the formability of the material in the range of studied deformation parameters. These maps are correlated to the microstructure at specific deformation parameters.

scholarly journals The Investigation on Flow Behavior of Powder Metallurgy Ti-10V-2Fe-3Al Alloy Using the Prasad Stability Criterion

2019 ◽  
Vol 50 (11) ◽  
pp. 5314-5323 ◽  
Author(s):  
Krystian Zyguła ◽  
Marek Wojtaszek ◽  
Oleksandr Lypchanskyi ◽  
Tomasz Śleboda ◽  
Grzegorz Korpała ◽  
...  
Keyword(s):  
Powder Metallurgy ◽  
Power Dissipation ◽  
Hot Deformation ◽  
High Efficiency ◽  
Flow Instability ◽  
Flow Behavior ◽  
Material Model ◽  
Instability Criterion ◽  
Processing Maps ◽  
Compression Tests

Abstract The hot deformation behavior of Ti-10V-2Fe-3Al alloy obtained by the powder metallurgy (PM) method was investigated. Material for the research was produced by blending of elemental powders followed by uniaxial hot pressing. Thermomechanical tests of Ti-10V-2Fe-3Al compacts were carried out to determinate the stress-strain relationships at the temperature range of 800 °C to 1000 °C and strain rate between 0.01 and 10 s−1. Based on the dynamic material model (DMM) theory, processing maps at constant strain value were developed using data obtained from hot compression tests. The processing maps were elaborated for the final strain value, which was 0.9, and with flow instability criterion domains applied to it. Two critical regions associated with the flow behavior of the investigated material were revealed. Microstructural changes during hot deformation at various temperatures and strain rates were discussed. The correlation between calculated efficiency of power dissipation, flow instability criterion, and microstructure evolution was determined. The presence of defects was confirmed in regions predicted by the instability maps. The microstructure of the investigated alloy, corresponding to the high efficiency of power dissipation characterized by the occurrence of dynamic recrystallization (DRX) phenomena, was also shown. Additionally, average hardness values in relation to variable process parameters were designated. Based on the conducted studies and analysis, processing windows for Ti-10V-2Fe-3Al alloy compacts were proposed.

Effect of β Annealing and near β Zone Hot Deformation on the Microstructure and Texture of TC18 Alloy

2016 ◽  
Vol 849 ◽  
pp. 226-231
Author(s):  
Yi Min Cui ◽  
Wei Wei Zheng ◽  
Feng Zhang ◽  
Ai Xue Sha
Keyword(s):  
Grain Boundary ◽  
Dynamic Recrystallization ◽  
Small Angle ◽  
Hot Deformation ◽  
Static Recrystallization ◽  
Dynamic Recovery ◽  
Fiber Texture ◽  
Dual Phase ◽  
Phase Zone ◽  
Β Phase

Forged TC18 alloy billets with strong <100> texture were selected to investigate the effects of β annealing and near β zone hot deformation on the microstructure and texture by means of optical microscopy, XRD and EBSD techniques. The results showed that the original <100> fiber texture can’t be eliminated through β annealing although completed static recrystallization happened during annealing. After deforming in near β phase zone, the microstructures were composed of elongated β grains. A lot of small angle boundaries were observed near the original β grain boundaries, indicating that dynamic recovery controlled the deformation. Dynamic recrystallization grains can only be seen at the original β grain boundary at the strain of 50%. <100>//TD and <111>//TD texture were generated during the near β zone hot deformation. Annealing at dual phase zone after hot deformation can effectively reduce the proportion of grains with <111> orientation, but the <100>//TD texture still existed.

Hot Deformation Behaviors of SiCp/Al Composites

2014 ◽  
Vol 1058 ◽  
pp. 165-169 ◽  
Author(s):  
Shi Ming Hao ◽  
Jing Pei Xie
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Hot Deformation ◽  
True Strain ◽  
Constant Strain Rate ◽  
Hot Compression ◽  
Compression Tests ◽  
Sensitive Material ◽  
2024 Aluminum Alloy ◽  
Deformation Behaviors

The hot deformation behaviors of 30%SiCp/2024 aluminum alloy composites was studied by hot compression tests using Gleeble-1500 thermomechanical simulator at temperatures ranging from 350-500°C under strain rates of 0.01-10 s-1. The true stress-true strain curves were obtained in the tests. Constitutive equation and processing map were established. The results show that the flow stress decreases with the increase of deformation temperature at a constant strain rate, and increases with the increase of strain rate at constant temperature, indicating that composite is a positive strain rate sensitive material. The flow stress behavior of composite during hot compression deformation can be represented by a Zener-Hollomon parameter in the hyperbolic sine form. Its activation energy for hot deformation Q is 183.251 kJ/mol. The optimum hot working conditions for this material are suggested.

scholarly journals Constitutive Behavior of an AA4032 Piston Alloy with Cu and Er Additions upon High-Temperature Compressive Deformation

2019 ◽  
Vol 51 (1) ◽  
pp. 467-481
Author(s):  
Suwaree Chankitmunkong ◽  
Dmitry G. Eskin ◽  
Chaowalit Limmaneevichitr
Keyword(s):  
Activation Energy ◽  
Flow Stress ◽  
Strain Rate ◽  
Hot Deformation ◽  
Base Alloy ◽  
True Strain ◽  
Constitutive Behavior ◽  
Compression Tests ◽  
Primary Si ◽  
Constitutive Parameters

Abstract Aluminum piston alloys of the AA4032 type are produced by direct-chill (DC) casting and subsequent forging; therefore, it is important to understand their thermomechanical behavior. In recent years, it was shown that additions of Cu and Er could improve mechanical properties of these alloys at room and high temperatures. In this work, we studied the constitutive behavior of AA4032-type alloys with and without Cu and Er additions. The experimental true stress–true strain curves were obtained by compression tests under various temperatures [683 K to 723 K (410 °C to 450 °C)] and strain rates (0.01 to 10 s−1) to determine constitutive parameters [strain-rate sensitivity, activation energy, and Zener–Hollomon (Z) parameter] for the hot deformation behavior of AA4032-type piston alloys with and without additions of Cu and Er. The flow stress decreased with increasing deformation temperature and decreasing strain rate. The results also showed that increasing the Cu content increased the flow stress over the applied range of deformation conditions due to solid-solution strengthening and the formation of primary Si particles, which led to an increase in the activation energy during hot deformation. Moreover, the main microstructural damage in the AA4032 alloy with 3.5 pct Cu was predominantly due to the cracking of primary Si particles. Additions of 0.4 pct Er and 3.5 pct Cu lower the activation energy of deformation, Q, as compared to the base alloy and the alloy with 3.5 pct Cu. The microstructures in the deformed specimens consisted of subgrains, recrystallized grains, and fine eutectic phases. The alloys containing Er demonstrated more polygonized grains at a low strain rate than the alloys without Er, indicating that Er hindered recrystallization development. The peak stress of the AA4032 alloy with 3.5 pct Cu alloy was higher than for the base AA4032 alloy and for the AA4032 alloy with 3.5 pct Cu and 0.4 pct Er additions, which was attributed to the prevalence of the work-hardening mechanism over the softening mechanism.

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