The role of anisotropy in the response of the titanium alloy Ti–6Al–4V to shock loading

Millett, J. C. F.; Whiteman, G.; Bourne, N. K.; Gray, George T.

doi:10.1063/1.2991164

Cited by 39 publications

(8 citation statements)

References 31 publications

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“…Experimental observations on rolled [1,3,4] and extruded [5] engineering alloys show that crystallographic and morphological textures can induce strongly anisotropic damage growth and fracture behavior. Texture has also been found to result in anisotropic spallation of low-symmetry metals under shock loading [6,7]. Most available theories of dilatational viscoplasticity, however, make use of the simplifying assumption that the matrix material is homogeneous and isotropic, and are therefore unable to capture texture effects.…”

Section: Introductionmentioning

confidence: 97%

Dilatational viscoplasticity of polycrystalline solids with intergranular cavities

Lebensohn

Idiart

Castañeda

et al. 2011

Philosophical Magazine

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We propose constitutive models for polycrystalline aggregates with intergranular cavities and test them against full-field numerical simulations. Such conditions are prevalent in many engineering applications and failure of metallic components (e.g. HIPing and other forming processes, spallation under dynamic loading conditions, etc.), where the dilatational effects associated with the presence of cavities must be accounted for, and standard polycrystalline models for incompressible plasticity are not appropriate. On the other hand, it is not clear that the use of porous plasticity models with isotropic matrix behavior is relevant, particularly, when large deformations can lead to significant texture evolution and therefore to strong matrix anisotropy. Of course, finite strains can also lead to significant changes in the porosity and pore shape, resulting in additional anisotropy development. In this work, we make use of 'variational linearcomparison' homogenization methods to develop constitutive models simultaneously accounting for texture of the matrix, porosity and average pore shape and orientation. The predictions of the models are compared with full-field numerical simulations based on fast Fourier transforms to study the influence of different microstructural features (e.g. overall porosity, texture of the matrix phase, single-crystal anisotropy, etc.) and type of loading (triaxiality) on the dilatational viscoplastic behavior of voided polycrystals. The results are also compared with the predictions of isotropic-matrix porous plasticity models to assess the effect of the possible matrix anisotropy in textured samples.

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Section: Introductionmentioning

confidence: 97%

Dilatational viscoplasticity of polycrystalline solids with intergranular cavities

Lebensohn

Idiart

Castañeda

et al. 2011

Philosophical Magazine

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“…Millett et al [67] studied the effects of crystallographic texture on the shock response of Ti6Al-4V by loading material with a strong texture in the longitudinal and radial directions. No variation in the equation of state was found between the two conditions, but it was shown that the shear strength (again, by using embedded manganin gauges in sectioned targets) was lower in the radial direction which was attributed to the orientation of the HCP unit cell relative to the loading direction.…”

Section: (A) Shock Response Of Titaniummentioning

confidence: 99%

The shock and spall response of three industrially important hexagonal close-packed metals: magnesium, titanium and zirconium

Hazell

Appleby-Thomas

Wielewski

et al. 2014

Phil. Trans. R. Soc. A.

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Magnesium, titanium and zirconium and their alloys are extensively used in industrial and military applications where they would be subjected to extreme environments of high stress and strain-rate loading. Their hexagonal close-packed (HCP) crystal lattice structures present interesting challenges for optimizing their mechanical response under such loading conditions. In this paper, we review how these materials respond to shock loading via plate-impact experiments. We also discuss the relationship between a heterogeneous and anisotropic microstructure, typical of HCP materials, and the directional dependency of the elastic limit and, in some cases, the strength prior to failure.

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“…The load-displacement responses of the high-purity Ti tested in shear differ substantially consistent with the large differences in the yield stresses of high-purity Ti [71] previously documented in the literature between in-plane and through-thickness orientations. The high-purity Ti displays a significant difference in its shear response between the TT and IP directions consistent with the strong basal texture of the material [72], making the TT direction the higher flow stress direction. Shear loading in both the TT and IP directions for the high-purity Ti displayed significant strain hardening, more than a factor of 2 increase in load carrying capacity after yield, with the hardening rate higher in the TT sample, as indicated in Fig.…”

Section: Mechanical Response Of the Materialsmentioning

confidence: 69%

Investigation of the shear response and geometrically necessary dislocation densities in shear localization in high-purity titanium

Zhu

Livescu

Harrington

et al. 2017

International Journal of Plasticity

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The influence of microstructural anisotropy on shear response of high-purity titanium was studied using the compact forced-simple-shear specimen (CFSS) loaded under quasi-static loading conditions. Postmortem characterization reveals significant difference in shear response of different directions in the same material due to material crystallographic texture anisotropy. Shear bands are narrower in specimens in which the shear zone is aligned along the direction with a strong {0001} basal texture. Twinning was identified as an active mechanism to accommodate strains in the shear region in both orientations. This study confirms the applicability of the CFSS design for the investigation of differences in the shear response of materials as a function of process-induced crystallographic texture. A detailed, systematic approach to quantifying shear band evolution by evaluating geometrically necessary dislocations (GND) associated with crystallographic anisotropy is presented. The results show that: i) line average GND density profiles, for Ti samples that possess a uniform equiaxed-grain structure, but with strong crystallographic anisotropy, exhibit significant differences in GND density close to the shear band center; ii) GND profiles decrease steadily away from the shear band as the plastic strain diminishes, in agreement with Ashby's theory of work hardening, where the higher GND density in the through-thickness (TT) orientation, leads to a higher flow stress in the shear band compared with inplane (IP) samples; iii) the anisotropy in deformation response is derived from initial crystallographic texture of the materials, where GND density of both and type slip are higher adjacent to the shear band in the through-thickness sample oriented away from easy slip, corresponding to higher energy absorption; and iv) the increase in grain average GND density was determined to have strong correlation to an increase in the Euler Φ angle of the grain average orientation, indicating an increased misorientation angle evolution from slip to slip.

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The role of anisotropy in the response of the titanium alloy Ti–6Al–4V to shock loading

Cited by 39 publications

References 31 publications

Dilatational viscoplasticity of polycrystalline solids with intergranular cavities

Dilatational viscoplasticity of polycrystalline solids with intergranular cavities

The shock and spall response of three industrially important hexagonal close-packed metals: magnesium, titanium and zirconium

Investigation of the shear response and geometrically necessary dislocation densities in shear localization in high-purity titanium

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