Effect of vacuum pressure on small crack propagation in Ti-6Al-4V

Yoshinaka, Fumiyoshi; Xue, Gaoge; Fujimura, Nao; Nakamura, Takashi

doi:10.1016/j.ijfatigue.2020.105961

Cited by 9 publications

(7 citation statements)

References 38 publications

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“…This local crack growth rate is two orders of magnitude higher than the maximum value of the macroscopic one which has been determined from µCT data. This observation matches with the results from [54] who measures a value of 1.4 × 10 −7 m striation spacing when Δ𝐾 = 18 MPa √ m for a crack under air environment in the same alloy cycled at 𝑅 = 0.1. A possible explanation for this apparently high crack growth rate in the facets is that the crack in the flat facets could stay arrested during several cycles (between 10 and 100) before propagating again.…”

Section: Fracture Surface Analysissupporting

confidence: 90%

Environment effect on internal fatigue crack propagation studied with in-situ X-ray microtomography

Hébrard¹,

Buffière²,

Palin‐Luc³

et al. 2023

Materials Science and Engineering: A

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Section: Fracture Surface Analysissupporting

confidence: 90%

Environment effect on internal fatigue crack propagation studied with in-situ X-ray microtomography

Hébrard¹,

Buffière²,

Palin‐Luc³

et al. 2023

Materials Science and Engineering: A

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“…Previous studies on Ti‐6Al‐4V indicated that internal cracks are similar to the cracks in a vacuum in terms of fractography and crack propagation rate 25,26 . The fracture surface topography exhibited a granular feature with rounded edges in both the internal cracks and cracks in a vacuum.…”

Section: Discussionmentioning

confidence: 83%

“…Previous studies on Ti-6Al-4V indicated that internal cracks are similar to the cracks in a vacuum in terms of fractography and crack propagation rate. 25,26 The fracture surface topography exhibited a granular feature with rounded edges in both the internal cracks and cracks in a vacuum. Meanwhile, the crack propagation rate of internal cracks was plotted in the range of 10 À13 to 10 À11 m/ cycle, which is in good agreement with that of the cracks in a vacuum.…”

Section: Discussionmentioning

confidence: 99%

Detection of small internal fatigue cracks in Ti‐6Al‐4V via synchrotron radiation nanocomputed tomography

Xue

Tomoda

Nakamura

et al. 2022

Fatigue Fract Eng Mat Struct

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Two types of synchrotron radiation computed tomography (SR‐CT)—projection CT (micro‐CT) and phase‐contrast imaging CT (nano‐CT)—were used to observe internal fatigue cracks in (α + β) Ti‐6Al‐4V alloy. Micro‐CT detected cracks in the specimen at ~1 μm spatial resolution, and the nano‐CT provided magnified images at ~200 nm spatial resolution. The crack initiation sites were clarified as the α‐phase for both the surface and internal cracks; however, their opening behaviors differed. A sharp crack tip was observed in the surface crack, and the crack tip opening displacement (CTOD) increased with an increase in the applied load. By contrast, a blunted crack tip, similar to that of a crack in a vacuum, was observed for the internal crack, and its CTOD remained almost constant regardless of the applied load. These phenomena are likely to explain the different behaviors of surface and internal cracks, particularly the slower growth rate of internal cracks, which leads to a longer fatigue life in the very high cycle fatigue regime.

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“…The experiment entailed fatigue tests and SR‐CT repeatedly conducted at SPring‐8. The obtained crack growth rate of internal cracks was extremely slow, less than 10 −10 m/cycle, which was attributed to the effect of the vacuum environment inside the internal cracks 31 …”

Section: Introductionmentioning

confidence: 96%

“…The obtained crack growth rate of internal cracks was extremely slow, less than 10 À10 m/cycle, which was attributed to the effect of the vacuum environment inside the internal cracks. 31 In our previous work, 29,30 we studied internal crack growth. Regarding crack initiation, the relationship between the number of cracks and the number of cycles was investigated.…”

Section: Introductionmentioning

confidence: 99%

Characterization of internal fatigue crack initiation in Ti‐6Al‐4V alloy via synchrotron radiation X‐ray computed tomography

Yoshinaka

Nakamura

Oguma

et al. 2023

Fatigue Fract Eng Mat Struct

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The initiation of internal fatigue cracks in very high cycle fatigue of Ti‐6Al‐4V alloy was investigated using synchrotron radiation X‐ray computed tomography (SR‐CT). Micro‐CT detected 28 cracks that were distributed across the examined volume of Ф1.8 × L 2.5 mm. No apparent correlation was observed between the spatial distribution, initial lengths, and initiation lives of cracks. The crack growth rate of the facet‐sized crack varied widely; some cracks propagated rapidly, whereas no crack growth was observed for other cracks over a specific period of time after detection. Using nano‐CT, the several grain‐sized internal cracks and their microstructures were clearly and nondestructively visualized. In the field of view, many primary α phases were detected; however, no other cracks were observed. The multiple facet initiation site, which is commonly observed for titanium alloys, might not be due to the concurrently initiated facets but may be caused by the small crack growth accompanied by facet formation.

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Effect of vacuum pressure on small crack propagation in Ti-6Al-4V

Cited by 9 publications

References 38 publications

Environment effect on internal fatigue crack propagation studied with in-situ X-ray microtomography

Environment effect on internal fatigue crack propagation studied with in-situ X-ray microtomography

Detection of small internal fatigue cracks in Ti‐6Al‐4V via synchrotron radiation nanocomputed tomography

Characterization of internal fatigue crack initiation in Ti‐6Al‐4V alloy via synchrotron radiation X‐ray computed tomography

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