Effect of Stress Ratio on Subsurface Fatigue Crack Initiation Behavior of Beta-Type Titanium Alloy.

Shiozawa, Kazuaki; Kuroda, Yasushi; Nishino, Seiichi

doi:10.1299/kikaia.64.2528

Cited by 13 publications

(18 citation statements)

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“…Generally speaking, ordinary fatigue crack initiation occurs mostly on the specimen surface owing to slip deformation. However, fatigue failure can occur at small internal defects in subsurface zones of a material, especially high‐strength steels, case‐hardened steels and aged titanium alloys 10–21 . Subsurface crack initiation is dominant at low stress amplitudes and high numbers of cycles, whereas surface fatigue crack initiation occurs at high stress amplitudes and low cycles.…”

Section: Nomenclaturementioning

confidence: 99%

S–N curve characteristics and subsurface crack initiation behaviour in ultra‐long life fatigue of a high carbon‐chromium bearing steel

Shiozawa

Ishihara

2001

Fatigue Fract Eng Mat Struct

307

194

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The S–N curve obtained from cantilever‐type rotary bending fatigue tests using hour‐glass‐shaped specimens of high carbon‐chromium bearing steel clearly distinguished the fracture modes into two groups each having a different crack origin. One was governed by crystal slip on the specimen surface, which occurred in the region of short fatigue life and a high stress amplitude level. The other was governed by a non‐metallic inclusion at a subsurface level which occurred in the region of long fatigue life and low stress amplitude. The inclusion developed a fish‐eye fracture mode that was distributed over a wide range of stress amplitude not only below the fatigue limit defined as the threshold for fracture due to the surface slip mode but also above the fatigue limit. This remarkable shape of the S–N curve was different from the step‐wise one reported in previous literature and is characterized as a duplex S–N curve composed of two different S–N curves corresponding to the respective fracture modes. From detailed observations of the fracture surface and the fatigue crack origin, the mechanisms for the internal fracture mode and the characteristics of the S–N curve are discussed.

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Section: Nomenclaturementioning

confidence: 99%

S–N curve characteristics and subsurface crack initiation behaviour in ultra‐long life fatigue of a high carbon‐chromium bearing steel

Shiozawa

Ishihara

2001

Fatigue Fract Eng Mat Struct

307

194

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“…Subsurface fatigue crack initiation has been reported in several α/β titanium alloys 1 –6 and has also been found in β titanium alloys 7 –12 . As possible crack initiation sites, α phase, α/β interface, and defects such as voids or pores have been considered 1 ,.…”

Section: Introductionmentioning

confidence: 98%

“…In reality, no defects have been identified at the crack initiation site. Instead, in β titanium alloys, a flat facet was seen at the crack origins, 7 –9 , 11 , 12 this suggests that microstructure may be related to the subsurface crack initiation process.…”

Section: Introductionmentioning

confidence: 98%

“…in long‐life region around or above 10 7 cycles to failure, thus fatigue strength continues to decrease beyond that level 1 ,. 5 , 11 , 12 This is very important when designing machine parts or components, because the strength at 10 7 cycles, like the fatigue limit in ferrous metals, has no meaning as a reference design stress. The stress ratio also exerted a significant influence on the crack initiation behaviour and subsurface crack origins tended to occur increasingly as the stress ratio increases 4 ,.…”

Section: Introductionmentioning

confidence: 99%

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Subsurface fatigue crack initiation in beta titanium alloys

Tokaji

Ohya

Kariya

2000

Fatigue Fract Eng Mat Struct

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“…Generally speaking, ordinary fatigue crack initiation occurs mostly on the specimen surface because of slip deformation of crystals or some surface defect. However, fatigue failure does occur at small internal defects in subsurface zones of a material, especially high‐strength steels, case‐hardened steels and aged titanium alloys 10–22 . Subsurface crack initiation is dominant at low‐stress amplitudes and high number of cycles, whereas the surface fatigue crack initiation occurs at high‐stress amplitudes and low cycles.…”

Section: Introductionmentioning

confidence: 99%

Very high‐cycle fatigue behaviour of shot‐peened high‐carbon–chromium bearing steel

Shiozawa

2002

Fatigue Fract Eng Mat Struct

184

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Effect of shot‐peening on fatigue behaviour in the gigacycle regime was investigated in order to clarify the duplex S–N curve characteristics. Cantilever‐type rotary bending fatigue tests were performed in laboratory air at room temperature by using hourglass‐shaped specimens of high‐carbon–chromium bearing steel, JIS SUJ2. Fatigue crack initiation site changed from the surface of untreated specimen to the subsurface of the specimen because of hardening and compressive residual stress with shot‐peening in the region of high‐stress amplitude. On the other hand, no difference in fatigue life controlled by the subsurface crack initiation between untreated specimen and shot‐peening one was observed in high‐cycle region. It was suggested that the S–N curve corresponding to the internal fracture mode is inherent in the material, as compared with the S–N curve of surface fracture mode, which is affected by surface conditions, environmental conditions and so on. Subsurface crack initiation and propagation behaviour were discussed under the detailed measurement of crack initiation area and shape of the fish‐eye fracture surface.

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Effect of Stress Ratio on Subsurface Fatigue Crack Initiation Behavior of Beta-Type Titanium Alloy.

Cited by 13 publications

References 0 publications

S–N curve characteristics and subsurface crack initiation behaviour in ultra‐long life fatigue of a high carbon‐chromium bearing steel

S–N curve characteristics and subsurface crack initiation behaviour in ultra‐long life fatigue of a high carbon‐chromium bearing steel

Subsurface fatigue crack initiation in beta titanium alloys

Very high‐cycle fatigue behaviour of shot‐peened high‐carbon–chromium bearing steel

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