Interaction effect of adjacent small defects on the fatigue limit of a medium carbon steel

Åman, Mari; Okazaki, Saburo; Matsunaga, Hisao; Marquis, Gary; Remes, Heikki

doi:10.1111/ffe.12482

Cited by 25 publications

(17 citation statements)

References 40 publications

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“…It has been reported that for various metallic materials, the fatigue limit as a crack‐growth threshold can accurately be predicted by the

\sqrt{area}

parameter model . This model states that Δ Κ th at a stress ratio of −1 depends on the size of the initial crack or defect and the hardness of the material, expressed by the following equation:

normalΔ Κ_{th} = 3.3 \times 10^{- 3} ((), italicHV + 120) {(\sqrt{area})}^{1 / 3} .

The unit is MPa

\sqrt{m}

for Δ Κ th .…”

Section: Resultsmentioning

confidence: 99%

Effect of defects on the fatigue limit of Ni‐based superalloy 718 with different grain sizes

Kevinsanny

Okazaki

Takakuwa

et al. 2019

Fatigue Fract Eng Mat Struct

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Tension‐compression fatigue tests were performed on two types of Ni‐based superalloy 718 with different microstructures in which small artificial defects of various sizes and shapes were introduced. The susceptibility of the fatigue strength to the defects varied significantly with the microstructure morphology, ie, a smaller grain size made the alloy more susceptible to defects. The fatigue limit as a small‐crack threshold was successfully predicted using the area parameter model. The evaluation of the fatigue limit was classified into the following three stages depending on the defect size: (a) harmless defect regime, (b) small‐crack regime, and (c) large‐crack regime. Such a classification enabled comprehensive evaluation of the fatigue limit in a wide range of defect size, considering (a) defect size over a range of small crack to large crack and (b) characteristics of matrix represented by grain size and hardness.

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“…It has been reported that for various metallic materials, the fatigue limit as a crack‐growth threshold can accurately be predicted by the

\sqrt{area}

parameter model . This model states that Δ Κ th at a stress ratio of −1 depends on the size of the initial crack or defect and the hardness of the material, expressed by the following equation:

normalΔ Κ_{th} = 3.3 \times 10^{- 3} ((), italicHV + 120) {(\sqrt{area})}^{1 / 3} .

The unit is MPa

\sqrt{m}

for Δ Κ th .…”

Section: Resultsmentioning

confidence: 99%

Effect of defects on the fatigue limit of Ni‐based superalloy 718 with different grain sizes

Kevinsanny

Okazaki

Takakuwa

et al. 2019

Fatigue Fract Eng Mat Struct

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“…This characteristic debonding behavior of MnS inclusions was independently confirmed by Maciejewski [13]. Åman et al [14] investigated the effects of interacting microstructural defects on the fatigue limit for a medium carbon steel. The investigations showed the fundamental influence of the underlying microstructure on the fatigue crack nucleation and short crack behavior.…”

Section: Introductionmentioning

confidence: 69%

“…Furthermore, they concluded that the largest microstructural defect determines the fatigue limit. Based on the experimental works [9][10][11][12][13][14], it is possible to extract the following key points: (a) the investigated martensitic steels SAE 4150 and SAE 4140 show fatigue crack nucleation on free surfaces as well as at oxidic and sulfidic inclusions with varying sizes, shapes and orientations to loading axis, (b) the MnS inclusions reveal a complex delamination behavior in case of transversal loading and (c) the lower bound of fatigue properties is controlled by the maximum size of non-metallic inclusions within the high stressed volumes [15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Micromechanical Modeling of Fatigue Crack Nucleation around Non-Metallic Inclusions in Martensitic High-Strength Steels

Schäfer

Sonnweber-Ribic

Hassan

et al. 2019

Metals

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Martensitic high-strength steels are prone to exhibit premature fatigue failure due to fatigue crack nucleation at non-metallic inclusions and other microstructural defects. This study investigates the fatigue crack nucleation behavior of the martensitic steel SAE 4150 at different microstructural defects by means of micromechanical simulations. Inclusion statistics based on experimental data serve as a reference for the identification of failure-relevant inclusions and defects for the material of interest. A comprehensive numerical design of experiment was performed to systematically assess the influencing parameters of the microstructural defects with respect to their fatigue crack nucleation potential. In particular, the effects of defect type, inclusion–matrix interface configuration, defect size, defect shape and defect alignment to loading axis on fatigue damage behavior were studied and discussed in detail. To account for the evolution of residual stresses around inclusions due to previous heat treatments of the material, an elasto-plastic extension of the micromechanical model is proposed. The non-local Fatemi–Socie parameter was used in this study to quantify the fatigue crack nucleation potential. The numerical results of the study exhibit a loading level-dependent damage potential of the different inclusion–matrix configurations and a fundamental influence of the alignment of specific defect types to the loading axis. These results illustrate that the micromechanical model can quantitatively evaluate the different defects, which can make a valuable contribution to the comparison of different material grades in the future.

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“…This equation is widely used for the prediction of the fatigue limit of numerous metallic materials with small defects and cracks. [30][31][32][33][34][35][36][37] It is worth noting that the model has been proven to give an accurate forecast of the fatigue limit of the Ti-6Al-4V alloy with small defects and cracks of diverse sizes and dimensions. [38,39] In the prior study by the author et al, the local R value was calculated according to the residual stress distribution in Equation 2, thereby enabling the successful prediction of the fatigue limit of an FOD specimen.…”

Section: Discussionmentioning

confidence: 99%

Effect of impact velocity and impact angle on residual stress fields caused by foreign object damage

Matsunaga

2020

Strain

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In order to study the residual stress induced by foreign object damage (FOD), the distribution of residual stress caused by the impact of a hard spherical body was measured via the sin2ψ technique, using synchrotron X‐ray. A steel sphere was impacted onto a flat surface of a Ti‐6Al‐4V alloy from an angle of either 90° or 45°, at a velocity of 180 m/s. The same sphere was also quasi‐statically pressed into the surface. In the cases of right‐angled impact and quasi‐static indentation, a compressive residual stress was extensively distributed inside the generated crater. No remarkable difference in residual stress distribution was noted between the dynamic case and the quasi‐static case. However, at an impact angle of 45°, a tensile residual stress that is more detrimental to fatigue strength was widely distributed inside the crater. Outside of the craters, tensile stress was generally observed in all cases.

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Interaction effect of adjacent small defects on the fatigue limit of a medium carbon steel

Cited by 25 publications

References 40 publications

Effect of defects on the fatigue limit of Ni‐based superalloy 718 with different grain sizes

Effect of defects on the fatigue limit of Ni‐based superalloy 718 with different grain sizes

Micromechanical Modeling of Fatigue Crack Nucleation around Non-Metallic Inclusions in Martensitic High-Strength Steels

Effect of impact velocity and impact angle on residual stress fields caused by foreign object damage

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