scholarly journals Hot Gas Pressure Forming of Ti-55 High Temperature Titanium Alloy Tubular Component

Materials ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 4636
Author(s):  
Kehuan Wang ◽  
Chenyu Shi ◽  
Shiqiang Zhu ◽  
Yongming Wang ◽  
Jintao Shi ◽  
...  
Keyword(s):  
Titanium Alloy ◽  
High Temperature ◽  
Tensile Deformation ◽  
Electron Backscatter Diffraction ◽  
Thickness Distribution ◽  
Tensile Tests ◽  
Gas Pressure ◽  
Uniaxial Tensile ◽  
Hot Gas ◽  
Tubular Component

In this paper, hot gas pressure forming (HGPF) of Ti-55 high temperature titanium alloy was studied. The hot deformation behavior was studied by uniaxial tensile tests at temperatures ranging from 750 to 900 °C with strain rates ranging from 0.001 to 0.05 s−1, and the microstructure evolution during tensile tests was characterized by electron backscatter diffraction. Finite element (FE) simulation of HGPF was carried out to study the effect of axial feeding on thickness distribution. Forming tests were performed to validate this process for Ti-55 alloy. Results show that when the temperature was higher than 750 °C, the elongation was large enough for HGPF of Ti-55 alloy. Dynamic recrystallization (DRX) occurred during the tensile deformation, which could refine the microstructure. The thickness uniformity of the formed part could be improved by increasing feeding length. The maximum thinning ratio decreased from 27.7% to 11.5% with the feeding length increasing from 0 to 20 mm. A qualified Ti-55 alloy component was successfully formed at 850 °C, the microstructure was slightly refined after forming, and the average post-form yield strength and peak strength were increased by 8.7% and 6.9%, respectively. Pre-heat treatment at 950 °C before HGPF could obtain Ti-55 alloy tubular component with bimodal microstructure and further improve the post-form strength.

scholarly journals A Study on Uniaxial Tensile Deformation Behavior of Superelastic Titanium Alloy

2020 ◽  
Vol 58 (3) ◽  
pp. 162-168
Author(s):  
Hye-Jin Jeong ◽  
Viet Tien Luu ◽  
Yong-Ha Jeong ◽  
Sung-Tae Hong ◽  
Heung Nam Han
Keyword(s):  
Titanium Alloy ◽  
Tensile Deformation ◽  
Electron Backscatter Diffraction ◽  
Early Stage ◽  
Beta Phase ◽  
Mechanical Twinning ◽  
Martensite Phase ◽  
Deformation Mechanisms ◽  
Dislocation Slip ◽  
Uniaxial Tensile

A superelastic titanium alloy was subjected to uniaxial tensile deformation at room temperature. The microstructural evolution and deformation mechanisms of the superelastic titanium alloy were investigated by electron backscatter diffraction (EBSD) and X-ray diffraction (XRD). Multiple deformation mechanisms including stress-induced martensitic transformation (SIMT), dislocation slip, {332}<113> and {112}<111> mechanical twinning were identified with the increase in uniaxial strain. In the early stage of deformation, a SIMT from the bcc beta phase to orthorhombic martensite phase dominantly occurred. As the deformation proceeded, the phase fraction of the remained martensite which did not return to beta phase obviously increased due to dislocation slip and mechanical twinning. The kernel average misorientation (KAM) value obtained from EBSD data gradually increased with increasing the deformation, indicating that the dislocation evolution was produced by slip. This was well matched with the trend in the full width at half maximum (FWHM) value of the peak profile obtained from XRD data. In addition, the fraction of the {332}<113> twin was lower than that of the {112}<111> twin in the initial specimen. However, the {332}<113> twin rapidly increased compared to the {112}<111> twin as deformation increased. Therefore, it is confirmed that {332}<113> twinning and dislocation slip were the dominant mechanisms during plastic deformation.

scholarly journals A Flow Stress Model of 300M Steel for Isothermal Tension

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 252
Author(s):  
Rongchuang Chen ◽  
Shiyang Zhang ◽  
Xianlong Liu ◽  
Fei Feng
Keyword(s):  
Flow Stress ◽  
Constitutive Model ◽  
Tensile Deformation ◽  
Flow Behavior ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Model Parameters ◽  
Average Deviation ◽  
Cross Sectional ◽  
300M Steel

To investigate the effect of hot working parameters on the flow behavior of 300M steel under tension, hot uniaxial tensile tests were implemented under different temperatures (950 °C, 1000 °C, 1050 °C, 1100 °C, 1150 °C) and strain rates (0.01 s−1, 0.1 s−1, 1 s−1, 10 s−1). Compared with uniaxial compression, the tensile flow stress was 29.1% higher because dynamic recrystallization softening was less sufficient in the tensile stress state. The ultimate elongation of 300M steel increased with the decrease of temperature and the increase of strain rate. To eliminate the influence of sample necking on stress-strain relationship, both the stress and the strain were calibrated using the cross-sectional area of the neck zone. A constitutive model for tensile deformation was established based on the modified Arrhenius model, in which the model parameters (n, α, Q, ln(A)) were described as a function of strain. The average deviation was 6.81 MPa (6.23%), showing good accuracy of the constitutive model.

scholarly journals An Experimental Study of the Tension-Compression Asymmetry of Extruded Ti-6.5Al-2Zr-1Mo-1V under Quasi-Static Conditions at High Temperature

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1299
Author(s):  
Chen Zhang ◽  
Dongsheng Li ◽  
Xiaoqiang Li ◽  
Yong Li
Keyword(s):  
High Temperature ◽  
Strain Hardening ◽  
Yield Stress ◽  
Mechanical Response ◽  
Tensile Deformation ◽  
Uniaxial Tensile ◽  
Tensile Direction ◽  
Stress Asymmetry ◽  
Static Conditions ◽  
Tension Compression Asymmetry

The tension-compression asymmetry (TCA) behavior of an extruded titanium alloy at high temperatures has been investigated experimentally in this study. Uniaxial tensile and compressive tests were conducted from 923 to 1023 K with various strain rates under quasi-static conditions. The corresponding yield stress and asymmetric strain hardening behavior were obtained and analyzed. In addition, the microstructure at different temperatures and stress states indicates that the extruded TA15 profile exhibits a significant yield stress asymmetry at different testing temperatures. The flow stress and yield stress during tension are greater than compression. The yield stress asymmetry decreases with the increase in temperature. The alloy also exhibits TCA behavior on the strain hardening rate. Its mechanical response during compression is more sensitive than tension. A dynamic recrystallization phenomenon is observed instead of twin generated in tension and compression under high-temperature quasi-static conditions. The grains are elongated along the tensile direction and deformed by about 45° along the compressive load axis. Finally, the TCA of Ti-6.5Al-2Zr-1Mo-1V (TA15) alloy is due to slip displacement. The tensile deformation activates basal <a>, prismatic <a> and pyramidal <c + a> slip modes, while the compressive deformation activates only prismatic <a> and pyramidal <c + a> slip modes.

Deformation Structures in a Duplex Stainless Steel

2018 ◽  
Vol 941 ◽  
pp. 176-181 ◽  
Author(s):  
Karin Yvell ◽  
Göran Engberg
Keyword(s):  
Electron Backscatter Diffraction ◽  
Texture Evolution ◽  
True Strain ◽  
Strain Curve ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Deformation Structure ◽  
Pole Figures ◽  
Two Phases ◽  
Backscatter Diffraction

The evolution of the deformation structure with strain has been studied using electron backscatter diffraction (EBSD). Samples from interrupted uniaxial tensile tests and from a cyclic tension/compression test were investigated. The evolution of low angle boundaries (LABs) was studied using boundary maps and by measuring the LAB density. From calculations of local misorientations, smaller orientation changes in the substructure can be illustrated. The different orientations developed with strain within a grain, due to operation of different slip systems in different parts of the grain, were studied using a misorientation profile showing substantial orientation changes after a true strain of 0.24. The texture evolution with increasing strain was followed by using inverse pole figures (IPFs). The observed substructure development in the ferritic and austenitic phases could be successfully correlated with the stress-strain curve from a tensile test. LABs were first observed in the different phases when the strain hardening rate changed in appearance indicating that cross slip started to operate as a significant dislocation recovery mechanism. The evolution of the deformation structure is concluded to occur in a similar manner in the austenitic and ferritic phases but with different texture evolution for the two phases.

Effect of Pulse Current on Mechanical Behavior of High Temperature Titanium Alloy Ti55

2021 ◽  
Vol 1035 ◽  
pp. 25-31
Author(s):  
Hai Feng Wan ◽  
Ai Jun Xu ◽  
Yun Long Huang ◽  
Ze Jun Tang
Keyword(s):  
Titanium Alloy ◽  
High Temperature ◽  
Tensile Properties ◽  
Pulse Current ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Electrical Parameters ◽  
Dislocation Movement ◽  
High Pulse ◽  
Material Forming

The effects of pulse current on the tensile properties of high temperature titanium alloy Ti55 were investigated by pulse current assisted uniaxial tensile test under different electrical parameters. It was found that with the increase of peak current and pulse width, the tensile properties of Ti55 are significantly improved. At the same time, the pulsation effect of current on the mechanical properties of Ti55 was investigated. The results show that the tensile displacement of low pulsation group was higher, while the elongation of high pulsation group was higher. In order to explore the mechanism of pulsation effect of current, EBSD was adopted. The results indicated that high pulse current can significantly promote the dislocation movement and recrystallization. In addition, some macrozones was found in low pulsation group, which indicated that high pulsation current was more suitable for material forming than low pulsation current.

Development of a Low Cost Process for Manufacturing of Ti-MMC by Roll-Diffusion-Bonding

2010 ◽  
Vol 638-642 ◽  
pp. 991-996 ◽  
Author(s):  
Claudio Testani ◽  
F. Ferraro
Keyword(s):  
Titanium Alloy ◽  
High Temperature ◽  
Diffusion Bonding ◽  
Pilot Plant ◽  
Low Cost ◽  
Thermal Spraying ◽  
Tensile Tests ◽  
Matrix Composites ◽  
Alloy Matrix ◽  
Metallographic Examination

Titanium-alloy matrix composites (TMC) are nowadays one of the material class with the highest specific resistance from room temperature up to 800° C. Centro Sviluppo Materiali SpA (CSM) efforts have been focused on the developing of an innovative solution to reduce the process costs. The new approach consists in an experimental “diffusion bonding” plant for co-rolling at high temperature sheets of titanium alloy and silicon carbide monofilaments fabrics. The result is a process cost reduction of about 40% respect to HIP process. The experimental pilot plant has been proposed for patent with n° 2006A000261 on may 2006. This paper describes the pilot plant and the process results. The metallographic examination on products shows full bonded samples (100 mm wide and 1500 mm long) obtained in a work field that is at least 100 times faster than that of HIP. High temperature tensile tests have been carried on Roll Diffusion Bonded specimens and the results are reported in comparison with those obtained by Isostatic Pressing (HIP) and Thermal- Spraying (TS) processes on the same composite.

scholarly journals Evolution of mechanical properties of Ti6242S alloy after oxidation in air at 560°C: influence of solid salts deposits

2020 ◽  
Vol 321 ◽  
pp. 04029
Author(s):  
Ioana POPA ◽  
Maxime BERTHAUD ◽  
Clément CISZAK ◽  
Jean-Michel BROSSARD ◽  
Daniel MONCEAU ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Titanium Alloy ◽  
High Temperature ◽  
Outer Part ◽  
Tensile Tests ◽  
Corrosion Mechanism ◽  
Good Oxidation Resistance ◽  
Aerospace Applications ◽  
Solid Deposit ◽  
Oxidation In Air

Titanium alloys are widely used in aerospace applications due to their good ratio of weight versus mechanical properties. When exposed to air at 560°C, Ti6242S titanium alloy presents very good oxidation resistance: a very thin oxide layer forms at its surface and oxygen dissolution inside the metallic material is rather limited. However, in real functioning conditions of the plane, near seas or oceans, the atmosphere contains NaCl, that can crystallise at the surface of hot parts. An active corrosion mechanism is established in these conditions, with catastrophic effect on the material behaviour at high temperature: very thick and brittle oxide scales and very important damaging of the metal outer part. Another issue is the formation of Na2SO4 specie by reaction of NaCl with kerosene combustion gases (SO2/SO3), leading to mixed NaCl/Na2SO4 deposits. The effect of exposure conditions on the mechanical properties of titanium alloy Ti6242S was evaluated through tensile tests performed on the raw alloy and after oxidation in air at 560°C of the specimens: without any deposit, with NaCl solid deposit, with NaCl/Na2SO4 solid deposit. The evolution of mechanical properties was interpreted in connexion with the microstructural modifications that occur during the high temperature ageing.

TEM Observations of Dislocation Emission at Grain Boundaries in Response to Uniaxial (Tensile) Straining

1981 ◽  
Vol 39 ◽  
pp. 296-297
Author(s):  
L.E. Murr
Keyword(s):  
Grain Boundaries ◽  
Tensile Deformation ◽  
Tensile Tests ◽  
Convincing Evidence ◽  
304 Stainless Steel ◽  
Uniaxial Tensile ◽  
Dislocation Emission ◽  
Quantitative Studies ◽  
Transmission Electron

Although it now seems to be generally recognized that grain boundaries and other interfaces are sources for dislocations, there are only scant few observations which tend to show convincing evidence for this. Murr earlier suggested that dislocation pile-ups in deformed metals and alloys (especially of low stacking-fault free energy) were primarily dislocation emission profiles, and more recent quantitative studies tend to unambiguously confirm this for uniaxial tensile deformation. Some of these features are illustrated in Fig. 1(a) and (b) which show a systematic increase in the number of dislocation profiles associated with grain boundary ledges at increasing tensile strains; observed in a Hitachi H.U. 200 F transmission electron microscope.The results shown in Fig. 1(a) and (b) were obtained as part of a systematic study of dislocation emission following the straining of 304 stainless steel sheet samples in separate, conventional tensile tests. Consequently these observations, while qualitatively and even quantitatively convincing, lack the force of direct, in-situ observations.

Degradation Mechanisms of Underfills Subjected to Isothermal Long-Term Aging From 150°C to 200°C

2020 ◽  
Author(s):  
Pradeep Lall ◽  
Yunli Zhang ◽  
Haotian Wu ◽  
Ed Davis ◽  
Jeff Suhling
Keyword(s):  
High Temperature ◽  
Tensile Tests ◽  
Optical Microscope ◽  
Mechanical Tests ◽  
Uniaxial Tensile ◽  
Cross Section Area ◽  
Section Area ◽  
Before And After ◽  
Damage Tolerant ◽  
High Temperature Operation

Abstract FCBGAs are finding applications in automotive underhood environments where they may be subjected to sustained temperatures of 125–200°C for sustained periods during operation. While, FCGBAs have been previously used in consumer applications where operating temperatures typically range in 55–85°C, relatively little is known on methods to design damage-tolerant packages in automotive underhood environments. There is insufficient information on plastic encapsulated electronic components capable of surviving high temperatures for long periods (&gt; 100,000 hours). In this paper, four different types of underfills has been cured and aged. Mechanical tests have been performed on all the four types of underfills too understand the degradation in properties under extended high temperature operation. Uniaxial tensile tests are conducted to study the elastic modulus, ultimate tensile strength and percentage elongation of the underfills. After uniaxial tensile tests, Optical Microscope, SEM and EDS are applied to study the microstructure behaviors of the cross-section area of the underfills. The experimental results are compared before and after aging tests, including pristine, 30 days, 60 days, 90days, 120 days and 240 days. The research focuses on microstructure-property-processing-performance relationships, building the relation between the microstructure evolution and macro-mechanical properties. Reliability physics of high temperature degradation of packaging material is studied.

Superplasticity in CP-Titanium Alloys

2007 ◽  
Vol 551-552 ◽  
pp. 373-378 ◽  
Author(s):  
X.J. Zhu ◽  
Ming Jen Tan ◽  
K.M. Liew
Keyword(s):  
High Temperature ◽  
Grain Growth ◽  
Initial Strain Rate ◽  
Tensile Tests ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Uniaxial Tensile ◽  
Step Method ◽  
Commercially Pure ◽  
Effects Of Temperature

In this work, studies were carried out to investigate the superplasticity of a commercially pure (CP) titanium alloy during high temperature deformation. Uniaxial tensile tests were carried out at 600, 750 and 800°C with an initial strain rate from 10-1s-1 to 10-4s-1. It was found that the alloy do not show good superplasticity due fast grain growth at high temperature and cavity. The effects of temperature on the grain growth and cavity phenomena as well as the dynamic recrystallization of the alloy were studied and a ‘two-step-method’ was introduced to increase the superplasticity of the alloy.

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