What Happens to the Fatigue Limit of Bearing Steel Without Nonmetallic Inclusions? : Fatigue Strength of Electron Beam Remelted Super Clean Bearing Steel

Murakami, Y.; Toriyama, Toshiyuki; Tsubota, Kazuichi; Furumura, Kyozaburo

doi:10.1520/stp12122s

Cited by 20 publications

(11 citation statements)

References 9 publications

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“…Few results are given in the specialized literature on this topic 1 . According to our own observations and those of Murakami et al ., 8 fatigue crack initiation in the gigacycle regime seems to occur essentially inside the sample and not at the surface as is observed for shorter lives.…”

Section: Discussionmentioning

confidence: 48%

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There is no infinite fatigue life in metallic materials

Bathias¹

1999

Fatigue Fract Eng Mat Struct

453

194

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Generally, the shape of the S–N curve beyond 107 cycles is unknown except in some statistical approaches, and this is also true for the fatigue limit. In the case of a statistical approach, the standard deviation applied to the average fatigue limit is certainly not the best way to reduce the risk of rupture in fatigue. Only the exploration of the life range between 106 and 1010 cycles will create a safer basis for modelling. Today, some piezoelectric fatigue machines are very reliable, capable of producing 1010 cycles in less than 1 week. We based our research on accelerated fatigue tests which were performed at 20 kHz in the gigacyclic fatigue regime in order to study several typical alloys from the aeronautical and space industries.

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Section: Discussionmentioning

confidence: 48%

“…Figure 11 presents an example of the N18 alloy. In this respect, the Murakami model 8 is a good approach to predict fatigue strength as depending on the inclusion size in the gigacycle regime 9 …”

Section: Discussionmentioning

confidence: 99%

There is no infinite fatigue life in metallic materials

Bathias¹

1999

Fatigue Fract Eng Mat Struct

453

194

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“…Murakami et al 33 . conducted rotary bending fatigue tests on a bearing steel produced by a special melting method.…”

Section: S–n Curvesmentioning

confidence: 99%

On the mechanism of fatigue failure in the superlong life regime (N>10⁷ cycles). Part 1: influence of hydrogen trapped by inclusions

Murakami

Nomoto

Ueda

2000

Fatigue Fract Eng Mat Struct

265

152

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The fracture surfaces of specimens of a heat‐treated hard steel, namely Cr–Mo steel SCM435, which failed in the regime of N = 105 to 5 × 108 cycles, were investigated by optical microscopy and scanning electron microscopy (SEM). Specimens having a longer fatigue life had a particular morphology beside the inclusion at the fracture origin. The particular morphology looked optically dark when observed by an optical microscope and it was named the optically dark area (ODA). The ODA looks a rough area when observed by SEM and atomic force microscope (AFM). The relative size of the ODA to the size of the inclusion at the fracture origin increases with increase in fatigue life. Thus, the ODA is considered to have a crucial role in the mechanism of superlong fatigue failure. It has been assumed that the ODA is made by the cyclic fatigue stress and the synergetic effect of the hydrogen which is trapped by the inclusion at the fracture origin. To verify this hypothesis, in addition to conventionally heat‐treated specimens (specimen QT, i.e. quenched and tempered), specimens annealed at 300 °C in a vacuum (specimen VA) and the specimens quenched in a vacuum (specimen VQ) were prepared to remove the hydrogen trapped by inclusions. The specimens VA and VQ, had a much smaller ODA than the specimen QT. Some other evidence of the influence of hydrogen on superlong fatigue failure are also presented. Thus, it is concluded that the hydrogen trapped by inclusions is a crucial factor which causes the superlong fatigue failure of high strength steels.

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“…This effect of inclusions on the fatigue limit is in fact generally accepted [49], [50]. Murakami et al observed that the fatigue limit of bearing steel tended to increase as the size of inclusions decreased over the years due to better steelmaking practices [51]. For 13%Cr-4%Ni steels, silicon and aluminum complex oxides are found in different proportion and sizes.…”

Section: 5mentioning

confidence: 90%

The effect of materials properties on the reliability of hydraulic turbine runners

Thibault

Gagnon

Godin

2015

International Journal of Fluid Machinery and Systems

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The failure of hydraulic turbine runners is a rare event. So in order to assess the reliability of these components one cannot rely solely on the number of observed failures in a given population. However, as there is a limited number of degradation mechanisms involved, it is possible to use physically-based reliability models. Such models are often more complicated but are able to account for physical parameters in the degradation process. They can therefore help provide solutions to improve reliability. With such models, the effect of materials properties on runner reliability can be highlighted. This paper presents a brief review of the Kitagawa-Takahashi diagram which links the damage tolerance approach, based on fracture mechanics, to the stress or strainlife approaches. Using simplified response spectra based on runner stress measurements, we will show how fatigue reliability is sensitive to materials fatigue properties, namely fatigue crack propagation behaviour and fatigue limit obtained on S-N curves. Furthermore, we will review the influence of the main microstructural features observed in 13%Cr-4%Ni stainless steels commonly used for runner manufacturing. The goal is ultimately to identify the most influential microstructural features and to quantify their effect on fatigue reliability of runners.

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What Happens to the Fatigue Limit of Bearing Steel Without Nonmetallic Inclusions? : Fatigue Strength of Electron Beam Remelted Super Clean Bearing Steel

Cited by 20 publications

References 9 publications

There is no infinite fatigue life in metallic materials

There is no infinite fatigue life in metallic materials

On the mechanism of fatigue failure in the superlong life regime (N>10⁷ cycles). Part 1: influence of hydrogen trapped by inclusions

The effect of materials properties on the reliability of hydraulic turbine runners

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What Happens to the Fatigue Limit of Bearing Steel Without Nonmetallic Inclusions? : Fatigue Strength of Electron Beam Remelted Super Clean Bearing Steel

Cited by 20 publications

References 9 publications

There is no infinite fatigue life in metallic materials

There is no infinite fatigue life in metallic materials

On the mechanism of fatigue failure in the superlong life regime (N>107 cycles). Part 1: influence of hydrogen trapped by inclusions

The effect of materials properties on the reliability of hydraulic turbine runners

Contact Info

Product

Resources

About

On the mechanism of fatigue failure in the superlong life regime (N>10⁷ cycles). Part 1: influence of hydrogen trapped by inclusions