Factors determining room temperature mechanical properties of bimodal microstructures in Ti-6Al-4V alloy

Ye, Chong; Bhattacharjee, Tilak; Park, Myeong-heom; Shibata, Akinobu; Tsuji, Nobuhiro

doi:10.1016/j.msea.2018.06.019

Cited by 77 publications

(8 citation statements)

References 16 publications

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“…β is softer than α p due to lower concentrations of solute Al in β [ 30 ], thus β should bear more significant deformation than the α p phase at the same stress, while due to the more numerous slip systems and greater deformation coordination in BCC β, parallel, deep SBs may be less likely to form in the β phase when the strain is relatively small ( Figure 6 and Figure 7 ). Caused by the different deformation behaviors between α p and β, stress concentration at the interface gradually increases with increasing strain, finally generating microcracks.…”

Section: Discussionmentioning

confidence: 99%

In Situ Observation of the Tensile Deformation and Fracture Behavior of Ti–5Al–5Mo–5V–1Cr–1Fe Alloy with Different Microstructures

Pan

Liu

et al. 2021

Materials

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The plastic deformation processes and fracture behavior of a Ti–5Al–5Mo–5V–1Cr–1Fe alloy with bimodal and lamellar microstructures were studied by room-temperature tensile tests with in situ scanning electron microscopy (SEM) observations. The results indicate that a bimodal microstructure has a lower strength but higher ductility than a lamellar microstructure. For the bimodal microstructure, parallel, deep slip bands (SBs) are first noticed in the primary α (αp) phase lying at an angle of about 45° to the direction of the applied tension, while they are first observed in the coarse lath α (αL) phase or its interface at grain boundaries (GBs) for the lamellar microstructure. The β matrix undergoes larger plastic deformation than the αL phase in the bimodal microstructure before fracture. Microcracks are prone to nucleate at the αp/β interface and interconnect, finally causing the fracture of the bimodal microstructure. The plastic deformation is mainly restricted to within the coarse αL phase at GBs, which promotes the formation of microcracks and the intergranular fracture of the lamellar microstructure.

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Section: Discussionmentioning

confidence: 99%

In Situ Observation of the Tensile Deformation and Fracture Behavior of Ti–5Al–5Mo–5V–1Cr–1Fe Alloy with Different Microstructures

Pan

Liu

et al. 2021

Materials

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“…The origin of these improved mechanical properties is usually attributed to the fact that dislocation gliding inside the α-grains was blocked at the interfaces between them and the transformed β-areas, i.e., the β-areas with a finer morphology acted as a strengthening component for the mechanical properties of the bimodal microstructure [39]. On the other hand, recent studies argued that plastic strain can localize preferentially within the transformed β-areas, and then propagate into the surrounding α-grains [40]. Strain gradients from the interface to the interior of α-grains were supposed to increase the number of geometrically necessary dislocations near the interface, which contribute to the enhanced work-hardening rate of the bimodal microstructure.…”

Section: Discussionmentioning

confidence: 99%

Recovery of Scratch Grooves in Ti-6Al-4V Alloy Caused by Reversible Phase Transformations

Шугуров

Панин

Дмитриев

et al. 2020

Metals

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The deformation behaviors of Ti-6Al-4V alloy samples with lamellar and bimodal microstructures under scratch testing were studied experimentally and using molecular dynamics simulation. It was found that the scratch depth in the sample with a bimodal microstructure was twice as shallow as that measured in the sample with a lamellar microstructure. This effect is attributed to the higher hardness of the sample with a bimodal microstructure and the larger amount of elastic recovery of scratch grooves in this sample. On the basis of the results of molecular dynamics simulation, a mechanism was proposed, which associates the recovery of the scratch grooves with the inhomogeneous vanadium distribution in the β-areas. The calculations showed that at a vanadium content typical for Ti-6Al-4V alloy, both the body-centered cubic (BCC) and hexagonal close-packed (HCP) structures can be more energetically favorable depending on the atomic volume. Therefore, compressive or tensile stresses induced by the indenter could facilitate β→α and α→β phase transformations, respectively, in the vanadium-depleted domains of the β-areas, which contribute to the recovery of the Ti-6Al-4V alloy subjected to scratching.

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“…Elemental partitioning, tailored through carefully designed thermal treatments, was recently demonstrated to significantly influence the strength and local deformation. [123,124] It is however difficult to decouple solid solution effects and microstructural scale effects that change simultaneously with annealing treatment. An example of annealing treatment effects on the relative strength of equiaxed a and transformed b in Ti-6Al-4V is shown in Figure 18.…”

Section: Slip Activity In Relation To Microstructure and Compositionmentioning

confidence: 99%

Microplasticity at Room Temperature in α/β Titanium Alloys

Hémery

Villechaise

Banerjee

2020

Metall Mater Trans A

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The current understanding of room temperature microplasticity in a/b titanium alloys is reviewed with a special emphasis on dual-phase engineering alloys. As the interplay between microstructure and deformation mechanisms governs both the microscale and macroscale mechanical response, a brief description of the main features of a/b microstructures is first provided. Elastic and plastic deformation in individual phases is then described. The complex interactions that govern the effect of grain boundaries, phase interfaces and microtexture on deformation behaviour are reviewed. Crystal plasticity simulations have evolved over the past decade as a key technique to obtain a mechanistic understanding of the deformation of Ti alloys. Micromechanical aspects are emphasized with a discussion of input parameters required to achieve realistic constitutive modeling. As microplasticity is especially relevant in cyclic loading such as experienced in-service by components, the current understanding of the relation of this regime with fatigue and dwell-fatigue behavior is briefly summarized in the final section.

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Factors determining room temperature mechanical properties of bimodal microstructures in Ti-6Al-4V alloy

Cited by 77 publications

References 16 publications

In Situ Observation of the Tensile Deformation and Fracture Behavior of Ti–5Al–5Mo–5V–1Cr–1Fe Alloy with Different Microstructures

In Situ Observation of the Tensile Deformation and Fracture Behavior of Ti–5Al–5Mo–5V–1Cr–1Fe Alloy with Different Microstructures

Recovery of Scratch Grooves in Ti-6Al-4V Alloy Caused by Reversible Phase Transformations

Microplasticity at Room Temperature in α/β Titanium Alloys

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