Effects of Crack Size, Stress Ratio and Hydrogen on the Near Threshold Fatigue Crack Propagation of High Strength Steel

Yanagihara, Kazutoshi; Ohyanagi, Satoshi; Kubota, Masanobu; Sakae, Chu; Kondo, Yoshiyuki

doi:10.2472/jsms.54.1237

Cited by 9 publications

(4 citation statements)

References 4 publications

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“…The width of the slits was 30 µm. Kondo et al showed that the ∆K th of high-strength steel with a crack length larger than 400 µm could be regarded as the ∆K(L) th [31]. Thus, the 400-µm deep slit simulated a large defect for deriving ∆K(L) th .…”

Section: Materials Usedmentioning

confidence: 99%

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Prediction of Fatigue Limit of Spring Steel Considering Surface Defect Size and Stress Ratio

Ishii

Takahashi

2021

Metals

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Surface defects decrease the fatigue limit of metals. In this study, the effects of surface defects on the fatigue limit of high-strength spring steel specimens were investigated. Several equations to predict the fatigue limit of specimens with surface defects were evaluated. Specimens with a semicircular slit with depths ranging from 30 to 400 µm were prepared. The Vickers hardness of the specimen was approximately 470 HV. Bending fatigue tests were performed at stress ratios ranging from −2 to 0.4. The fatigue test results showed that the fatigue limit decreased with an increase in the slit depth. Moreover, the maximum defect size that resulted in a decrease in the fatigue limit was dependent on the stress ratio. On comparing the predicted fatigue limits with the experimental results, it was confirmed that the predictions made based on the modified El-Haddad model were in good agreement with the experimentally obtained data. Thus, this model can be used to evaluate the fatigue limit of high-strength steels containing small surface defects with different stress ratios.

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Section: Materials Usedmentioning

confidence: 99%

“…The ultimate tensile strength (σ UTS ) and 0.2% offset yield strength (σ 0.2 ) of SUP9A after the heat treatment were 1580 and 1170 MPa, respectively. than 400 µm could be regarded as the Δ ( ) [31]. Thus, the 400-µm deep slit simulated a large defect for deriving ∆ ( ) .…”

Section: Materials Usedmentioning

confidence: 99%

Prediction of Fatigue Limit of Spring Steel Considering Surface Defect Size and Stress Ratio

Ishii

Takahashi

2021

Metals

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“…While the former can diffuse at room temperature and contributes to hydrogen embrittlement under static loading, the latter does not influence the static strength because of high binding energy between hydrogen and its trap site (5) . Under cyclic loading, diffusible hydrogen decreases the fatigue strength such as the fatigue limit (7) and the threshold stress intensity factor (8) . However, the influence of irreversible hydrogen on the fatigue strength in steels has not been clarified so far.…”

Section: Introductionmentioning

confidence: 99%

Influence of Irreversible Hydrogen on the Fatigue Strength in Cold Drawn High Strength Steel

Minoshima

Nakatani

Sugeta

et al. 2008

JMMP

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Slow strain rate tensile (SSRT) tests and fatigue tests were conducted to investigate the influence of irreversible hydrogen on the quasi static SSRT strength and fatigue strength for cold drawn eutectoid steels which were cathodically hydrogen charged. Internal hydrogen states were changed as follows: (a) virgin sample, (b) the sample that contained both diffusible and irreversible hydrogen, and (c) the one that contained only irreversible hydrogen. The SSRT strength properties of only irreversible hydrogen contained sample were the same as that of virgin sample, whereas those of the sample having both diffusible and irreversible hydrogen were smaller than the others. This indicates that only the diffusible hydrogen caused hydrogen embrittlement under the quasi-static loading. Contrary to this, the fatigue strength of the sample having both diffusible and irreversible hydrogen was lower than that of virgin sample. However, the influence of irreversible hydrogen on the fatigue strength was unclear since S-N curves had a large scatter. This is due to the fact that the fatigue crack was initiated at internal inclusion. Therefore, the fatigue strength was discussed based on the stress intensity factor, ∆K inc , calculated from stress and inclusion size. ∆K inc giving the same N f decreased in the order of virgin sample, irreversible hydrogen charged sample and the sample having diffusible and irreversible hydrogen, indicating irreversible hydrogen caused the fatigue strength degradation.

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“…The described investigation with local resolution of dislocation dynamics bounded to crystal plasticity reflects on wear or tribological contact. For example, Kubota et al [9] addressed the issue of fretting fatigue in austenitic stainless steel system by concluding the significant life decrease that was caused by hydrogen interaction. Such results combined with basic inherent mechanics become more understandable and can shade light on structural integrity phenomena.…”

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confidence: 98%

Near surface modification affected by hydrogen interaction: Global supplemented by local approach

Katz

Tymiak

2008

Strength Mater

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Effects of Crack Size, Stress Ratio and Hydrogen on the Near Threshold Fatigue Crack Propagation of High Strength Steel

Cited by 9 publications

References 4 publications

Prediction of Fatigue Limit of Spring Steel Considering Surface Defect Size and Stress Ratio

Prediction of Fatigue Limit of Spring Steel Considering Surface Defect Size and Stress Ratio

Influence of Irreversible Hydrogen on the Fatigue Strength in Cold Drawn High Strength Steel

Near surface modification affected by hydrogen interaction: Global supplemented by local approach

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