Revisiting the lamellar globularization behavior of a two-phase titanium alloy from the perspective of deformation modes

Wang, L.; Fan, Xiaoguang; Zhan, Mei; Jiang, Xin; Liang, Yongfeng; Zheng, H.J.; Liang, Weijie

doi:10.1016/j.jmatprotec.2020.116963

Cited by 19 publications

(4 citation statements)

References 36 publications

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“…As can be seen in Figures 6c and 8c, after deformation at 830 • C, material furnace-cooled or water-quenched after the β-annealing treatment exhibits the presence of equiaxed α grains within a transformed β matrix, which indicates that this temperature is just below the T βt . A similar behavior has been reported for titanium alloy TA15, in which the deformation above a critical globularization strain [39] at temperatures close to T βt influenced the volume fraction and aspect ratio of the α phase [40]. On the other hand, the sample that was air-cooled after the β annealing (Figure 7c) exhibits a microstructure consisting of a combination of elongated and equiaxed α grains in a transformed β matrix.…”

Section: Resultssupporting

confidence: 80%

Effect of Initial Microstructure on the Temperature Dependence of the Flow Stress and Deformation Microstructure under Uniaxial Compression of Ti-407

Barboza,

López,

Guajardo

et al. 2024

Metals

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In this study, the influence of initial microstructure and deformation temperature on the flow stress behavior and microstructural evolution of TIMETAL®407 (Ti-407) alloy are investigated. For this purpose, compression cylinders were β-annealed at 940 °C and then cooled to room temperature using furnace cooling, static air, and water quenching to promote three initial microstructures with different α lath thicknesses. The annealed cylinders were compressed isothermally in the range of 750 °C to 910 °C at a constant crosshead speed of 0.05 mm/s up to an engineering strain of −0.8. The resulting stress–strain curves are discussed in terms of the morphology and distribution of the α and β phases. It was found that flow stress is inversely proportional to deformation temperature for all initial microstructures. At the lowest temperatures, compressive yield strength was higher in water-quenched and air-cooled samples than in furnace-cooled specimens, suggesting that the acicular α-phase morphology obtained by rapid cooling could enhance mechanical strength by hindering dislocation motion. Two high-temperature flow regimes were determined based on the shape of the flow stress curves, indicating microstructural changes occurring during deformation. At higher temperatures, the effect of the initial microstructure is negligible as the primary α phase is transformed to the β phase at around 850 °C irrespective of the initial α-lath thickness.

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Section: Resultssupporting

confidence: 80%

Effect of Initial Microstructure on the Temperature Dependence of the Flow Stress and Deformation Microstructure under Uniaxial Compression of Ti-407

Barboza,

López,

Guajardo

et al. 2024

Metals

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“…(1) The peak stress and the amount of flow softening decreased with increases in defor- As mentioned above, the spheroidization behavior differs when the c-axis of the α lamellae tilt from the compression axis varies, which can lead to α spheroidization inhomogeneity. In recent years, researchers have proposed that spheroidization inhomogeneity can be improved by changing the strain path [43,45].…”

Section: Discussionmentioning

confidence: 99%

Dynamic Spheroidization Mechanism and Its Orientation Dependence of Ti-6Al-2Mo-2V-1Fe Alloy during Subtransus Hot Deformation

Ge,

Zhan,

et al. 2023

Materials

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The dynamic spheroidization mechanism and its orientation dependence in Ti-6Al-2Mo-2V-1Fe alloys during subtransus hot deformation were studied in this work. For this purpose, hot compression tests were carried out at temperatures of 780–880 °C, with strain rates of 0.001–0.1 s−1. Based on SEM, EBSD and TEM characterization, the results showed that the aspect ratio of the α phase decreased with increasing deformation temperatures and decreasing strain rates. At 880 °C/0.001 s−1, the aspect ratio of the α phase was the smallest at 2.05. The proportion of HAGBs decreased with increasing temperatures and strain rates, which was different from the trend of the spheroidization; this indicated that the formation of HAGBs was not necessary for the spheroidization process. Furthermore, the formation of the α/α interface was related to the evolution of dislocations and twin boundaries at high (880 °C) and low temperatures (780 °C), respectively. Moreover, the dependence of lamellar spheroidization on the crystallographic orientation tilt from the compression direction (θ) was clarified: when θ was between 45° and 60°, both the prism <a> slip and basal <a> slip systems were activated together, which was more favorable for spheroidization. This study could provide guidance for titanium alloy process designs and microstructure regulation.

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“…At light deformation, the α and β phases can rotate synergistically with keeping basic BOR. When the strain increases, the coordinated rotation between the α and β phase becomes difficult, and the correspondence of BOR is obviously deviated, as shown in Figure 5 f. Wang et al [ 29 ] reported the pole figures of the α and β phase under different strains in TA15 alloys, and the orientation relationship deviation of the two phases became larger when the strain increased. Meanwhile, the scattered (0001) α pole figure of α phase proves that more substructures are generated at a higher strain ( Figure 5 f).…”

Section: Resultsmentioning

confidence: 99%

Static Globularization Behavior and Artificial Neural Network Modeling during Post-Annealing of Wedge-Shaped Hot-Rolled Ti-55511 Alloy

Shi

Kong³

et al. 2023

Materials

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The globularization of the lamellar α phase by thermomechanical processing and subsequent annealing contributes to achieving the well-balanced strength and plasticity of titanium alloys. A high-throughput experimental method, wedge-shaped hot-rolling, was designed to obtain samples with gradient true strain distribution of 0~1.10. The samples with gradient strain distribution were annealed to obtain the gradient distribution of globularized α phase, which could rapidly assess the globularization fraction of α phase under different conditions. The static globularization behavior under various parameters was systematically studied. The applied prestrain provided the necessary driving force for static globularization during annealing. The substructure evolution and the boundary splitting occurred mainly at the early stage of annealing. The termination migration and the Ostwald ripening were dominant in the prolonged annealing. A backpropagation artificial neural network (BP-ANN) model for static globularization was developed, which coupled the factors of prestrain, annealing temperature, and annealing time. The average absolute relative errors (AARE) for the training and validation set are 3.17% and 3.22%, respectively. Further sensitivity analysis of the factors shows that the order of relative importance for static globularization is annealing temperature, prestrain and annealing time. The developed BP-ANN can precisely predict the static globularization kinetic curves without overfitting.

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Revisiting the lamellar globularization behavior of a two-phase titanium alloy from the perspective of deformation modes

Cited by 19 publications

References 36 publications

Effect of Initial Microstructure on the Temperature Dependence of the Flow Stress and Deformation Microstructure under Uniaxial Compression of Ti-407

Effect of Initial Microstructure on the Temperature Dependence of the Flow Stress and Deformation Microstructure under Uniaxial Compression of Ti-407

Dynamic Spheroidization Mechanism and Its Orientation Dependence of Ti-6Al-2Mo-2V-1Fe Alloy during Subtransus Hot Deformation

Static Globularization Behavior and Artificial Neural Network Modeling during Post-Annealing of Wedge-Shaped Hot-Rolled Ti-55511 Alloy

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