Superplasticity in Fine Grain Ti-6Al-4V Alloy: Mechanical Behavior and Microstructural Evolution

Despax, Laurie; Vidal, Vanessa; Delagnes, Denis; Dehmas, Moukrane; Geyer, Morgane; Matsumoto, Hiroaki; Velay, Vincent

doi:10.4028/www.scientific.net/ddf.385.137

Cited by 4 publications

(3 citation statements)

References 15 publications

(23 reference statements)

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“…Results from the constant strain rate tests and the stable necking free flow observed allows us to suggest that microstructure evolution was the main reason for the difference in strain hardening behaviour. The strain hardening was observed as a result of dynamic grain growth, which is in agreement with [42,43,44,45,46]. The main suggested reason for the softening is as a result of continuous dynamic recrystallization [47].…”

Section: Discussionsupporting

confidence: 74%

Superplasticity of Ti-6Al-4V Titanium Alloy: Microstructure Evolution and Constitutive Modelling

et al. 2019

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Determining a desirable strain rate-temperature range for superplasticity and elongation-to-failure are critical concerns during the prediction of superplastic forming processes in α + β titanium-based alloys. This paper studies the superplastic deformation behaviour and related microstructural evolution of conventionally processed sheets of Ti-6Al-4V alloy in a strain rate range of 10–5–10–2 s–1 and a temperature range of 750–900 °C. Thermo-Calc calculation and microstructural analysis of the as-annealed samples were done in order to determine the α/β ratio and the grain size of the phases prior to the superplastic deformation. The strain rate ranges, which corresponds to the superplastic behaviour with strain rate sensitivity index m ˃ 0.3, are identified by step-by-step decreasing strain rate tests for various temperatures. Results of the uniaxial isothermal tensile tests at a constant strain rate range of 3 × 10−4–3 × 10−3 s−1 and a temperature range of 800–900 °C are presented and discussed. The experimental stress-strain data are utilized to construct constitutive models, with the purpose of predicting the flow stress behaviour of this alloy. The cross-validation approach is used to examine the predictability of the constructed models. The models exhibit excellent approximation and predictability of the flow behaviour of the studied alloy. Strain-induced changes in the grain structure are investigated by scanning electron microscopy and electron backscattered diffraction. Particular attention is paid to the comparison between the deformation behaviour and the microstructural evolution at 825 °C and 875 °C. Maximum elongation-to-failure of 635% and low residual cavitation were observed after a strain of 1.8 at 1 × 10−3 s−1 and 825 °C. This temperature provides 23 ± 4% β phase and a highly stable grain structure of both phases. The optimum deformation temperature obtained for the studied alloy is 825 °C, which is considered a comparatively low deformation temperature for the studied Ti-6Al-4V alloy.

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Section: Discussionsupporting

confidence: 74%

Superplasticity of Ti-6Al-4V Titanium Alloy: Microstructure Evolution and Constitutive Modelling

et al. 2019

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“…Owing to its industrial importance, superplasticity of titanium alloys is a well-developed phenomenon [29][30][31][32][33][34][35]. Ti-6Al-4V is widely studied alloy that exhibits an equiaxed recrystallized structure before superplastic deformation [10,36,37].…”

Section: Introductionmentioning

confidence: 99%

Initial microstructure influence on Ti–Al–Mo–V alloy's superplastic deformation behavior and deformation mechanisms

Mosleh

Котов

Vidal

et al. 2021

Materials Science and Engineering: A

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Superplastic forming is an effective way to manufacture complex-shaped parts of titanium-based alloys. This paper studies the influence of the initial microstructure and its strain-induced evolution on superplastic deformation behavior and the formability of a titanium-based alloy. Two types of Ti-Al-V-Mo alloy samples having a different fraction of recrystallized grains before the start of the superplastic deformation were studied. The deformation behavior, including strain hardening and strain rate sensitivity of the flow stress, was analyzed in a temperature range of 775°C to 900°C and a strain rate range of 10 -5 to 10 -2 s -1 . Strain-induced changes of the microstructure within the bulk of the samples and on the surface of the pre-polished samples were studied during superplastic deformation with a constant strain rate. The dynamic recrystallization and dynamic grain growth in the volume of the samples and the multiple slip bands on the samples' surface were revealed after superplastic deformation. The grain structure evolution and slip bands localization depended on the samples' initial microstructure. The results showed that the samples with an increased fraction of recrystallized grains exhibited better superplasticity and higher quality of the formed parts with a more uniform thickness distribution across the section than the samples with a lower initial recrystallized fraction.

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“…The most of theoretical and experimental studies of superplastic properties and deformation behaviour in the superplastic conditions were carried out on Ti-6Al-4V alloy. The main reason is that Ti-6Al-4V alloy is a widely used commercially available superplastic alloy [14,23,[32][33][34][35][36][24][25][26][27][28][29][30][31]. For various application titanium-based alloys of another chemical compositions are also required and their deformation behaviour and microstructural evolution in superplastic state should be studied.…”

Section: Introductionmentioning

confidence: 99%

Microstructure Evolution of Ti-Al-Mo-V Titanium Alloy During the Superplastic Forming with FES Estimated Strain Rates Across the Formed Parts at Constant Gas Pressure

Mosleh

Котов

Медведева

et al. 2020

SSP

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This paper studies the influence of the strain rate during the superplastic forming on the microstructure evolution of Ti-4Al-3Mo-1V titanium alloy. The finite elements simulation (FES) of the superplastic forming process at a temperature of 875 °C, which considered to be the optimum forming temperature of this alloy, and at a constant uniform gas pressure of 0.4, 0.7, and 1 MPa were performed. The strain rate response across the formed part via FES at each applied gas pressure was analyzed. The superplastic forming using the same forming condition of the FES, applied gas pressure and forming time, was performed via lab forming machine. In initial state before forming, the studied alloy exhibits a mixture of lamellar and equiaxed grain structure. The microstructure evolution after the superplastic forming process for each applied gas pressure was investigated. It was observed that the lamellar microstructure significantly affects the superplastic forming process and the uniformity of the thickness profile after forming.

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Superplasticity in Fine Grain Ti-6Al-4V Alloy: Mechanical Behavior and Microstructural Evolution

Cited by 4 publications

References 15 publications

Superplasticity of Ti-6Al-4V Titanium Alloy: Microstructure Evolution and Constitutive Modelling

Superplasticity of Ti-6Al-4V Titanium Alloy: Microstructure Evolution and Constitutive Modelling

Initial microstructure influence on Ti–Al–Mo–V alloy's superplastic deformation behavior and deformation mechanisms

Microstructure Evolution of Ti-Al-Mo-V Titanium Alloy During the Superplastic Forming with FES Estimated Strain Rates Across the Formed Parts at Constant Gas Pressure

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