The influence of building direction on the fatigue crack propagation behavior of Ti6Al4V alloy produced by selective laser melting

Xu, Zhaowen; Liu, A.; Wang, X.S.

doi:10.1016/j.msea.2019.138409

Cited by 65 publications

(39 citation statements)

References 21 publications

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“…Nevertheless, a possible control of the surface properties depending on the process optimization has yet to be fully described. One of the most recently studied parameters to analyze the outcomes of additive technologies on the final properties of metal samples is the building strategy [54][55][56][57][58][59]. Differently from the other parameters of the printing process that are often previously optimized and set according to the material, the equipment, and the selected application, the building direction is an investigable, editable, and optimizable constraint that has been demonstrated to affect different features of as-built metal specimens.…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, SLM samples have been produced with different building orientations to determine how the tensile, fatigue, and general anisotropies of their mechanical properties can be affected by this parameter [57][58][59]. This paper aimed to introduce a critical comparison between Ti6Al4V samples fabricated by SLM and EBM at different building angles.…”

Section: Introductionmentioning

confidence: 99%

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Selective Laser Melting and Electron Beam Melting of Ti6Al4V for Orthopedic Applications: A Comparative Study on the Applied Building Direction

et al. 2020

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The 3D printing process offers several advantages to the medical industry by producing complex and bespoke devices that accurately reproduce customized patient geometries. Despite the recent developments that strongly enhanced the dominance of additive manufacturing (AM) techniques over conventional methods, processes need to be continually optimized and controlled to obtain implants that can fulfill all the requirements of the surgical procedure and the anatomical district of interest. The best outcomes of an implant derive from optimal compromise and balance between a good interaction with the surrounding tissue through cell attachment and reduced inflammatory response mainly caused by a weak interface with the native tissue or bacteria colonization of the implant surface. For these reasons, the chemical, morphological, and mechanical properties of a device need to be designed in order to assure the best performances considering the in vivo environment components. In particular, complex 3D geometries can be produced with high dimensional accuracy but inadequate surface properties due to the layer manufacturing process that always entails the use of post-processing techniques to improve the surface quality, increasing the lead times of the whole process despite the reduction of the supply chain. The goal of this work was to provide a comparison between Ti6Al4V samples fabricated by selective laser melting (SLM) and electron beam melting (EBM) with different building directions in relation to the building plate. The results highlighted the influence of the process technique on osteoblast attachment and mineralization compared with the building orientation that showed a limited effect in promoting a proper osseointegration over a long-term period.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Selective Laser Melting and Electron Beam Melting of Ti6Al4V for Orthopedic Applications: A Comparative Study on the Applied Building Direction

et al. 2020

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“…The microstructure heterogeneity, which includes the presence of large columnar grains, strong solidification texture, and continuous GB-α, is considered causing this mechanical property anisotropy. In AMed Ti-64, the columnar prior β grains have the long axes aligned with the fabrication direction and short axes perpendicular to the build direction, and the strain incompatibility between the columnar prior β grains could result in the crack preferentially initiating at grain boundaries [40,41,44]. Furthermore, the boundaries of the columnar prior β grains are decorated with GB-α.…”

Section: Discussionmentioning

confidence: 99%

“…In the horizontal sample of SLMed Ti-6Al-4V treated at 850 • C for 2 h, continuous grain boundary α phase could be identified at the fracture surface (Figure 11a). Continuous GB-α was known to nucleate cracks and serve as a potential crack pathway under tensile loading [41,42]. Furthermore, the presence of continuous GB-α was correlated with the columnar prior β grain, and the long axes of the prior β grain which were decorated with continuous GB-α phase are subjected to tension axis in the horizontal sample [19].…”

Section: Fracture Surface Characterizationmentioning

confidence: 99%

Effects of Post Heat Treatments on Microstructures and Mechanical Properties of Selective Laser Melted Ti6Al4V Alloy

Liu

et al. 2021

Metals

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The unique thermal history of selective laser melting (SLM) can lead to high residual stress and a non-equilibrium state in as-fabricated titanium alloy components and hinders their extensive use. Post heat treatment, as a classical and effective way, could transform non-equilibrium α’ martensite and achieves desirable mechanical performance in SLMed Ti alloys. In this study, we aimed to establish the correlation between the microstructure and mechanical performances of SLMed Ti6Al4V (Ti-64) by using different heat treatment processes. The columnar prior β grain morphology and grain boundary α phase (GB-α) after different heat treatment processes were characterized, with their influences on the tensile property anisotropy fully investigated. Scanning electron microscope (SEM) observation of the fracture surface and its cross-sectional analysis found that the tensile properties, especially the ductility, were affected by the GB-α along the β grain boundary. Furthermore, the discontinuous ratio of GB-α was firstly proposed to quantitatively predict the anisotropic ductility in SLMed Ti-64. This study provides a step forward for achieving the mechanical property manipulation of SLMed Ti-64 parts.

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“…10. In these cases, it was assumed that cracks initiated from the microstructure, most probably from α laths or colonies as report in the literature [14,27,28] for similar alloys.…”

Section: Fatigue Damage Mechanismsmentioning

confidence: 99%

High-cycle fatigue behavior of a laser powder bed fusion additive manufactured Ti-6Al-4V titanium: Effect of pores and tested volume size

Pessard

Lavialle

Laheurte

et al. 2021

International Journal of Fatigue

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This work is focused on the effect of natural defect on the fatigue resistance of a laser powder bed fusion additively manufactured Ti-6Al-4V titanium. To reveal the fatigue strength variability and its sensitivity to the defect size, push-pull fatigue tests have been undertaken on specimens with different sizes of highly loaded volume of material. In order to easily vary the size of the highly loaded volume, specimens containing different numbers of surface hemispherical shape holes of 600 µm in diameter have been tested. This method also allowed to test small volume which triggered crack initiation from microstructural features.The fatigue damage mechanisms observed and the average natural defect size measured on the failure surfaces depend on the size of the highly stressed region. A higher fatigue strength is observed for smaller stressed volumes and defect free regions. To reduce the impact lack-offusion on fatigue and increase the probability of triggering crack initiation from a microstructural feature, the specimens were built in the horizontal direction. For specimens where fatigue cracks initiated at natural discontinuities, the results reported in a Kitagawa-Takahashi diagram revealed a critical defect size ( √ area) in the range of 30 µm. In addition, a probabilistic approach based on the weakest link theory is proposed. The model describes a probabilistic Kitagawa-Takahashi diagram accounting for the size of both the highly stressed volume and the natural defect.

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The influence of building direction on the fatigue crack propagation behavior of Ti6Al4V alloy produced by selective laser melting

Cited by 65 publications

References 21 publications

Selective Laser Melting and Electron Beam Melting of Ti6Al4V for Orthopedic Applications: A Comparative Study on the Applied Building Direction

Selective Laser Melting and Electron Beam Melting of Ti6Al4V for Orthopedic Applications: A Comparative Study on the Applied Building Direction

Effects of Post Heat Treatments on Microstructures and Mechanical Properties of Selective Laser Melted Ti6Al4V Alloy

High-cycle fatigue behavior of a laser powder bed fusion additive manufactured Ti-6Al-4V titanium: Effect of pores and tested volume size

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