Microstructural analysis on boundary sliding and its accommodation mode during superplastic deformation of Ti–6Al–4V alloy

Kim, J.S.; Lee, Y.T.; Park, C.G.; Lee, C.S.

doi:10.1016/s0921-5093(98)01157-5

Cited by 122 publications

(41 citation statements)

References 24 publications

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“…The superplastic behavior of metals has been used to form complex shaped lightweight engineering components, especially for aerospace applications (Mabuchi and Higashi, 1999). The dominant deformation mechanism for this type of plastic deformation is grain rotation and grain boundary sliding (Kim et al, 1999). Such relative displacement of grains is accommodated by the distribution of matter within the mantle adjacent to grain boundaries (Ridley, 1989;Pilling, 1985).…”

Section: Damage Due To Superplastic Void Growthmentioning

confidence: 99%

A Review on Damage Mechanisms, Models and Calibration Methods under Various Deformation Conditions

Lin

Liu

Dean

2005

International Journal of Damage Mechanics

144

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The development of microdamage under the deformation conditions of high temperature creep, cold metal forming, superplastic forming, and hot metal forming has been reviewed and discussed, and typical constitutive equations developed to model the individual damage mechanisms are summarized. Based on the microstructural analysis of the key damage features for metallic materials under a wide range of deformation conditions, a set of schematic diagrams is designed to illustrate the major types of damage mechanisms. This helps researchers and engineers to understand the major cause of failure of materials under different deformation conditions and to select simple and appropriate mechanism-based damage equations to predict the damage evolution. Further discussions are carried out on the dominant damage mechanisms in hot metal forming conditions and it is concluded that the dominant damage mechanism can be 'grain boundary (creeptype) damage' or 'plasticity-induced (ductile) damage' depending on the material microstructure and deformation rate. In the case of grain boundary damage in hot forming, the shape of microdefects is different from those in high temperature creep and superplastic forming although all of those result in intergranular failure of materials. Furthermore, damage calibration techniques for different conditions of plastic deformation are summarized and discussed.KEY WORDS: damage mechanisms, damage calibrations, creep and viscoplasticity, cold and hot metal forming.

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Section: Damage Due To Superplastic Void Growthmentioning

confidence: 99%

A Review on Damage Mechanisms, Models and Calibration Methods under Various Deformation Conditions

Lin

Liu

Dean

2005

International Journal of Damage Mechanics

144

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“…Therefore, α phase should be the dominating phase during deformation ≤800°C, and the main superplastic deformation mechanism should be related to α/α GBS at 800°C in this study. It was reported that for the two-phase Ti-6Al-4V alloy, α/β phase boundary sliding (PBS) shows a smaller sliding resistance than GBS during superplastic deformation [25], and thus α/α GBS and α/β PBS should concurrently dominate the superplastic deformation in this study. It agrees with the inference from Fig.…”

Section: Resultsmentioning

confidence: 78%

Achieving superior low temperature and high strain rate superplasticity in submerged friction stir welded Ti-6AI-4V alloy

Zhang

Zeng

et al. 2017

Sci. China Mater.

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The superplastic forming of Ti alloy welds has great application prospects in producing integrated components. However, the nugget zone (NZ) of the Ti alloy welds, produced by fusion welding or conventional friction stir welding (FSW), consists of lamellar microstructure, which exhibits either low superplasticity or high superplastic temperautre and low strain rate. As a result, the NZ plays a leading role in hindering the superplastic forming of the whole welds. In this study, submerged friction stir welding (SFSW) was conducted in Ti-6Al-4V alloy for the first time, and a defectfree weld with the NZ consisting of a strip microstructure was obtained. The NZ exhibited a low-temperature superplasticity at 600°C, which was the lowest superplastic temperature ever reported in the Ti alloy welds. Besides, at 800°C, the NZ showed high strain rate (3×10 −2 s −1 ) superplasticity and a largest elongation of 615% at 1×10 −3 s −1 . Compared to conventional FSW joints, the NZ of SFSW joint exhibited a much lower flow stress and a decrease in optimal superplastic temperature by 100°C. This is mainly attributed to the easy globularization of the strip microstructure, enhancing the ability of grain/phase boundary sliding.

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“…The initial unrelaxed configuration is achieved by distributing the special density of dislocations randomly, as the with high local dislocation density and a soft grain regions with low dislocation density [35][36] . From Fig.…”

Section: The Effect Of Grain Size On Microscopic Deformation Fieldmentioning

confidence: 99%

Evolution of surface grain structure and mechanical properties in orthogonal cutting of titanium alloy

Bai

Tong

et al. 2016

J. Mater. Res.

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Abstract:In this study, a mesoscale dislocation simulation method was developed to study the orthogonal cutting of Titanium alloy. The evolution of the surface grain structure and its effects on the mechanical properties was studied using two-dimensional climb assisted dislocation dynamic technology. The motions of edge dislocations in an elastic matrix such as dislocation nucleation, lock, interaction with obstacles and grain boundaries, and annihilation were tracked. The results showed that the machined surface has a graded microstructure composed of ultrafine grains. A grain refinement process was observed in micro-cutting of titanium alloy. The process can be described as follows: (i) the development of dislocation lines in original grains, (ii) the formation of dense dislocation bands, (iii) the transformation of dislocation bands into subgrain boundaries, and (iv) the continuous dynamic recrystallization in subgrain boundaries. The fine-grains formed in this process bring appreciable scale effect and a mass of dislocations pile up in the grain boundary and persistent slip band (PSB). In particular, the flow stress and hardening rate was reduced by dislocation climb. However, this effect is significantly weakened when grain size was less than 1.65 µm. In addition, a Hall-Petch type relation is predicted depending on the amount of slips, the dislocation density, the grain arrangement and the range of grain sizes to which a Hall-Petch expression is fit. The numerical results obtained were compared with experimental data gathered from literature and a satisfied agreement was found.

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Microstructural analysis on boundary sliding and its accommodation mode during superplastic deformation of Ti–6Al–4V alloy

Cited by 122 publications

References 24 publications

A Review on Damage Mechanisms, Models and Calibration Methods under Various Deformation Conditions

A Review on Damage Mechanisms, Models and Calibration Methods under Various Deformation Conditions

Achieving superior low temperature and high strain rate superplasticity in submerged friction stir welded Ti-6AI-4V alloy

Evolution of surface grain structure and mechanical properties in orthogonal cutting of titanium alloy

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