Acceleration of Superlong Fatigue Failure by Hydrogen Trapped by Inclusions and Elimination of Conventional Fatigue Limit

Murakami, Yukitaka; Konishi, Hironobu; Takai, Kenichi; Murakami, Yasuo

doi:10.2355/tetsutohagane1955.86.11_777

Cited by 34 publications

(33 citation statements)

References 23 publications

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“… 10–13 It has been pointed out for the first time by Murakami et al . 4–7 that fatigue failure after ultralong life fatigue (i.e. beyond N = 10 7 cycles) is presumed to be influenced by hydrogen trapped by inclusions.…”

Section: Materials Specimen and Experimental Methodsmentioning

confidence: 99%

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Mechanism of fatigue failure in ultralong life regime

Murakami

Yokoyama²,

Nagata

2002

Fatigue Fract Eng Mat Struct

244

177

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The fatigue fracture surfaces of specimens of heat treated hard steels which failed in the regime of N = 105 to 5 × 108 cycles, were investigated by optical microscopy and SEM. Specimens having a longer fatigue life had a particular morphology beside the inclusion at the fracture origin. The particular morphology looked optically dark and in the previous paper it was named the Optically Dark Area, ODA. The roughness inside ODA is larger than outside ODA. 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 ultra long life fatigue failure. Direct evidences of existence of hydrogen at the inclusion at fracture origin are presented. It is presumed that the ODA is made by the cyclic stress coupled with the hydrogen which is trapped by the inclusion at the fracture origin. To verify the influence of hydrogen, specimens containing different levels of hydrogen were prepared by different heat treatments. The results obtained by fatigue tests of these specimens suggest that the hydrogen trapped by inclusions is a crucial factor which causes the ultra long fatigue failure of high strength steels. Aspects of the double S–N curve are also discussed in terms of experimental methods, specimen size and statistical distribution of inclusions sizes.

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Section: Materials Specimen and Experimental Methodsmentioning

confidence: 99%

“…Miller and O'Donnell 3 and Murakami, Nomoto and Ueda 4 discussed several possible factors which may cause fatigue failure in the regime of N > 10 7 cycles. The effect of internal hydrogen trapped by non‐metallic inclusions on high cycle fatigue was first indicated by Murakami et al 4–7 . Murakami et al.…”

Section: Introductionmentioning

confidence: 95%

Mechanism of fatigue failure in ultralong life regime

Murakami

Yokoyama²,

Nagata

2002

Fatigue Fract Eng Mat Struct

244

177

View full text Add to dashboard Cite

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“…Murakami et al 11,[15][16][17] showed that the high cycle fatigue strength is affected by the size of inclusions and hydrogen trapped around inclusions during heat treatment. Murakami and Nagata 11,[15][16][17] showed that the tension-compression fatigue limit of a high strength steel is declined remarkably by hydrogen-charging.…”

Section: Initiation Of Fatigue Crack At An Inclusion Pro-mentioning

confidence: 99%

“…Murakami and Nagata 11,[15][16][17] showed that the tension-compression fatigue limit of a high strength steel is declined remarkably by hydrogen-charging. They concluded that the reason is the effect of diffusible hydrogen, which diffuses freely in the matrix.…”

Section: Initiation Of Fatigue Crack At An Inclusion Pro-mentioning

confidence: 99%

Influence of Hydrogen on Fatigue Property of Suspension Spring Steel with Artificial Corrosion Pit after Multi-step Shot Peening

et al. 2015

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In order to reduce the weight of the suspension springs by increasing the strength level of the steels used, improvement of the corrosion fatigue property is the most important issue. This study investigated, the effect of residual stress, artificial corrosion pit depth and diffusible hydrogen on rotary bending fatigue properties of specimens after double shot and triple shot peening. The following conclusions were obtained:(1) Fatigue limits of specimens having the artificial corrosion pit of 250 μm depth with and without the charged hydrogen are improved remarkably by the triple shot peening.(2) Fish-eye fatigue fracture with an inclusion as the fatigue crack initiation site occurs frequently due to the charged hydrogen.(3) A good relationship between fatigue limit after shot peening and compressive residual stress at the bottom of the artificial corrosion pit is obtained regardless of the depth of the artificial corrosion pit.KEY WORDS: high strength low alloy steel; corrosion fatigue; shot peening; residual stress; hydrogen; fish-eye fatigue fracture.

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“…Our approach is drawn primarily from the studies of hydrogen-assisted fatigue-crack growth described in refs. [34][35][36][37][38][39][40].…”

Section: Introductionmentioning

confidence: 99%