Analysis of high flow stress and microstructural evolution of TC6 titanium alloy during isothermal forging

2004 ◽  
Vol 20 (10) ◽  
pp. 1257-1260 ◽  
Author(s):  
A.-M. Xiong ◽  
M.-Q. Li ◽  
W.-C. Huang ◽  
S.-H. Chen ◽  
H. Lin
Keyword(s):  
Titanium Alloy ◽  
Flow Stress ◽  
Microstructural Evolution ◽  
High Flow ◽  
Isothermal Forging ◽  
High Flow Stress

Hot Stamping of Titanium Alloy Sheets into U Shape with Concave Bottom and Joggle Using Resistance Heating

2016 ◽  
Vol 716 ◽  
pp. 915-922 ◽  
Author(s):  
Tomoyoshi Maeno ◽  
Yuya Yamashita ◽  
Ken-Ichiro Mori
Keyword(s):  
Titanium Alloy ◽  
Flow Stress ◽  
Partial Resistance ◽  
Hot Stamping ◽  
Alloy Sheet ◽  
High Flow ◽  
Resistance Heating ◽  
High Flow Stress ◽  
Reduction In Area

The hot stamping of α+β titanium alloy sheet into U shape with concave bottom using resistance heating were performed. Since both edges of the sheet in contact with a pair of electrodes were not heated, cracks occurred around the corners of the bottom due to the partially high flow stress. The cracks were prevented by slitting both edges before resistance heating because of the elongation of the edges. In addition, the hot stamping of titanium alloy sheet into joggle using partial resistance heating were performed. The distortion of sheet was reduced by reduction in area of resistance heating

Prediction of Flow Stress Anisotropy and Tension Compression Asymmetry of Hot Rolled AZ31B Mg Alloy

2014 ◽  
Vol 911 ◽  
pp. 178-184 ◽  
Author(s):  
Majid Al-Maharbi ◽  
Ibrahim Karaman
Keyword(s):  
Flow Stress ◽  
Mechanical Response ◽  
High Flow ◽  
Mg Alloy ◽  
Stress Anisotropy ◽  
Self Consistent ◽  
Tension And Compression ◽  
High Flow Stress ◽  
Hot Rolled ◽  
Tension Compression Asymmetry

The mechanical response of a hot rolled polycrystalline AZ31B Mg plate along its two directions is predicted using a visco-plastic self-consistent (VPSC) model coupled with a dislocation-based hardening scheme. The hardening response along the in-plane and through thickness directions of the plate was successfully predicted in tension and compression. The high flow stress anisotropy and tension/compression asymmetry of the alloy is attributed mainly to the directionality of the tensile twinning. The high hardening rate after twinning is also predicted successfully using the above mentioned hardening scheme.

scholarly journals Plasticity of Cu nanoparticles: Dislocation-dendrite-induced strain hardening and a limit for displacive plasticity

2013 ◽  
Vol 4 ◽  
pp. 173-179 ◽  
Author(s):  
Antti Tolvanen ◽  
Karsten Albe
Keyword(s):  
Molecular Dynamics ◽  
Flow Stress ◽  
Solid State ◽  
Force Field ◽  
Strain Hardening ◽  
High Flow ◽  
Cu Nanoparticles ◽  
Partial Dislocations ◽  
High Flow Stress ◽  
Dynamics Simulations

The plastic behaviour of individual Cu crystallites under nanoextrusion is studied by molecular dynamics simulations. Single-crystal Cu fcc nanoparticles are embedded in a spherical force field mimicking the effect of a contracting carbon shell, inducing pressure on the system in the range of gigapascals. The material is extruded from a hole of 1.1–1.6 nm radius under athermal conditions. Simultaneous nucleation of partial dislocations at the extrusion orifice leads to the formation of dislocation dendrites in the particle causing strain hardening and high flow stress of the material. As the extrusion orifice radius is reduced below 1.3 Å we observe a transition from displacive plasticity to solid-state amorphisation.

scholarly journals Microstructural Evolution and Refinement Mechanism of a Beta–Gamma TiAl-Based Alloy during Multidirectional Isothermal Forging

Materials ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 2496 ◽  
Author(s):  
Kai Zhu ◽  
Shoujiang Qu ◽  
Aihan Feng ◽  
Jingli Sun ◽  
Jun Shen
Keyword(s):  
Dynamic Recrystallization ◽  
Microstructural Evolution ◽  
Lamellar Microstructure ◽  
Phase Region ◽  
Second Step ◽  
Electron Backscattered Diffraction ◽  
Isothermal Forging ◽  
Continuous Dynamic Recrystallization ◽  
Mixture Phase ◽  
Refinement Mechanism

Multidirectional isothermal forging (MDIF) was used on a Ti-44Al-4Nb-1.5Cr-0.5Mo-0.2B (at. %) alloy to obtain a crack-free pancake. The microstructural evolution, such as dynamic recovery and recrystallization behavior, were investigated using electron backscattered diffraction and transmission electron microscopy methods. The MDIF broke down the initial near-lamellar microstructure and produced a refined and homogeneous duplex microstructure. γ grains were effectively refined from 3.6 μm to 1.6 μm after the second step of isothermal forging. The ultimate tensile strength at ambient temperature and the elongation at 800 °C increased significantly after isothermal forging. β/B2→α2 transition occurred during intermediate annealing, and α2 + γ→β/B2 transition occurred during the second step of isothermal forging. The refinement mechanism of the first-step isothermal forging process involved the conversion of the lamellar structure and discontinuous dynamic recrystallization (DDRX) of γ grains in the original mixture-phase region. The lamellar conversion included continuous dynamic recrystallization and DDRX of the γ laths and bugling of the γ phase. DDRX behavior of γ grains dominated the refinement mechanism of the second step of isothermal forging.

Microstructural Evolution in the TC17 Titanium Alloy Processed During Laser Stereo Forming

2021 ◽  
Vol 30 (4) ◽  
pp. 2967-2976
Author(s):  
Shan Liang ◽  
Jinghui Li ◽  
Qiang Zhang ◽  
Jing Chen
Keyword(s):  
Titanium Alloy ◽  
Microstructural Evolution

scholarly journals Hot Deformation Behavior and Processing Maps of a New Ti-6Al-2Nb-2Zr-0.4B Titanium Alloy

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2456
Author(s):  
Zhijun Yang ◽  
Weixin Yu ◽  
Shaoting Lang ◽  
Junyi Wei ◽  
Guanglong Wang ◽  
...  
Keyword(s):  
Titanium Alloy ◽  
Flow Stress ◽  
Constitutive Equation ◽  
Deformation Mechanism ◽  
Power Dissipation ◽  
Hot Deformation ◽  
Dissipation Rate ◽  
Dynamic Recovery ◽  
Processing Maps ◽  
Temperature Range

The hot deformation behaviors of a new Ti-6Al-2Nb-2Zr-0.4B titanium alloy in the strain rate range 0.01–10.0 s−1 and temperature range 850–1060 °C were evaluated using hot compressing testing on a Gleeble-3800 simulator at 60% of deformation degree. The flow stress characteristics of the alloy were analyzed according to the true stress–strain curve. The constitutive equation was established to describe the change of deformation temperature and flow stress with strain rate. The thermal deformation activation energy Q was equal to 551.7 kJ/mol. The constitutive equation was ε ˙=e54.41[sinh (0.01σ)]2.35exp(−551.7/RT). On the basis of the dynamic material model and the instability criterion, the processing maps were established at the strain of 0.5. The experimental results revealed that in the (α + β) region deformation, the power dissipation rate reached 53% in the range of 0.01–0.05 s−1 and temperature range of 920–980 °C, and the deformation mechanism was dynamic recovery. In the β region deformation, the power dissipation rate reached 48% in the range of 0.01–0.1 s−1 and temperature range of 1010–1040 °C, and the deformation mechanism involved dynamic recovery and dynamic recrystallization.

The Effect of Isothermal Forging Process Parameters on the Microstructure and the Properties of TA15 Near α Titanium Alloy

2007 ◽  
Vol 26-28 ◽  
pp. 367-371
Author(s):  
Hong Zhen Guo ◽  
Zhang Long Zhao ◽  
Bin Wang ◽  
Ze Kun Yao ◽  
Ying Ying Liu
Keyword(s):  
Titanium Alloy ◽  
High Temperature ◽  
Tensile Properties ◽  
Process Parameters ◽  
Spherical Shape ◽  
Deformation Degree ◽  
Isothermal Forging ◽  
Forging Process ◽  
Α Phase ◽  
Strip Shape

In this paper the effect of isothermal forging process parameters on the microstructure and the mechanical properties of TA15 titanium alloy was researched. The results of the tests indicate that, in the range of temperature of 850 °C~980 °C and deformation degree of 20%~60%, with the increase of temperature or deformation, as the reinforcement of deformation recrystallization, the primary α-phase tends to the spherical shape and secondary α-phase transforms from the acicular shape to fine and spherical shape with disperse distribution, which enhance the tensile properties at room and high temperature. With the increment of forging times, the spheroidization of primary α-phase aggrandizes and secondary α-phase transforms from spherical and acicular shape to wide strip shape, which decrease the tensile properties at room and high temperature. The preferable isothermal forging process parameters are temperature of 980 °C, deformation degree of 60%, and few forging times.

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