Fatigue crack non-propagation assisted by nitrogen-enhanced dislocation planarity in austenitic stainless steels

Habib, Kishan; Koyama, Motomichi; Tsuchiyama, Toshihiro; Noguchi, Hiroshi

doi:10.1016/j.ijfatigue.2017.07.019

Cited by 14 publications

(5 citation statements)

References 36 publications

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“…In fact, as demonstrated later, the high fatigue limit of the Fe-25Cr-1N steel originates from the occurrence of non-propagating fatigue cracks. Therefore, as similarly reported in a previous work [7], the reason for the higher fatigue life associated with the crack propagation resistance is expected to arise from the enhancement of the dislocation planarity due to Cr-N solute interactions. As mentioned in the introduction, we attempted to provide microstructural image-based evidences for the contribution of the dislocation planarity to the crack resistance using ECCI coupled with the replica technique.…”

Section: Resultssupporting

confidence: 67%

“…The dislocation planarity has been recognized to be controlled by a reduction in the stacking fault energy [4,5] and formation of a Cr-N atomistic interaction in austenitic steels [6]. In particular, our previous study revealed that the dislocation planarity associated with the Cr-N interaction positively enhances the crack resistance [7]. However, the nature of the effects of the crack tip dislocation on the crack resistance has not been clarified yet.…”

Section: Introductionmentioning

confidence: 98%

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Visualization of dislocations through electron channeling contrast imaging at fatigue crack tip, interacting with pre-existing dislocations

Habib

Koyama

Tsuchiyama

et al. 2017

Materials Research Letters

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The dislocation pattern at the tip of a non-propagating fatigue crack in an Fe-25Cr-1N steel (mass%) was characterized by electron channeling contrast imaging. Planar dislocation arrays on two different slip planes were observed at the crack tip. Each planar dislocation array acts as a barrier to the motion of the other planar dislocations on different slip planes, contributing to the enhancement of the resistance to the crack propagation. IMPACT STATEMENT This paper employs 'electron-channeling-contrast-imaging (ECCI) in scanning electron microscope' technique to visualize fatigue crack tip dislocations in high nitrogen steel, and it showed highly planar dislocations interacting with pre-existing dislocations assisting non-propagating fatigue crack.

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Section: Resultssupporting

confidence: 67%

Section: Introductionmentioning

confidence: 98%

Visualization of dislocations through electron channeling contrast imaging at fatigue crack tip, interacting with pre-existing dislocations

Habib

Koyama

Tsuchiyama

et al. 2017

Materials Research Letters

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“…In addition, uncertain problems remain regarding small crack growth. Mode II type crack growth associated with damage (lattice defect) accumulation is one remaining unknown, but has frequently been observed in various types of metal including steel and titanium alloy (Habib et al 2017;Maenosono et al 2018Maenosono et al , 2019 ). The ease of Mode II crack growth affects the crack roughness (crack growth path), and discontinuous crack growth, and highly disturbs the mechanical laws of fatigue crack growth.…”

Section: Discussionmentioning

confidence: 99%

Microstructural Crack Tip Plasticity Controlling Small Fatigue Crack Growth

Koyama

Nishikawa

Tsuzaki

2022

The Plaston Concept

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In this chapter, we present a metallurgical–mechanical mechanism-based strategy for the design of fatigue-resistant metals. Specifically, we elucidate the importance of the metallurgical microstructure in a mechanical singular field (crack tip). The fatigue crack growth resistance is controlled through the crack tip “plasticity”, and the effect of the associated microstructure becomes significant when the crack is “small (or short)”. More importantly, the resistance to small crack growth determines a major portion of fatigue life and strength. Therefore, the microstructural crack tip plasticity is a key breakthrough to the development of fatigue-resistant metals. As successful examples of this concept, we introduce the effects of grain refinement, martensitic transformation, strain aging, dislocation planarity enhancement, and microstructure heterogeneity on small fatigue crack growths.

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“…The resulting images look similar as the micrographs from dark-field imaging in transmission electron microscopy (TEM). This technique has shown its capability in studying HE related deformation information in a variety of materials with satisfying results [25,[45][46][47][48][49]. The theoretical and practical details of the ECCI technique can be found in Ref [50].…”

Section: Characterizationmentioning

confidence: 98%

Hydrogen-enhanced fatigue crack growth behaviors in a ferritic Fe-3wt%Si steel studied by fractography and dislocation structure analysis

Wan

Alvaro

Olden

et al. 2019

International Journal of Hydrogen Energy

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The effect of hydrogen (H) on the fatigue behavior is of significant importance for metallic structures. In this study, the hydrogen-enhanced fatigue crack growth rate (FCGR) tests on in-situ electrochemically H-charged ferritic Fe-3wt%Si steel with coarse grain size were conducted. Results showed strong difference between the H-charged and the non-charged conditions (reference test in laboratory air) and were in good agreement with the results from literature. With H-charging, the fracture morphology changed from transgranular (TG) type to "quasi-cleavage" ("QC"), with a different fraction depending on the loading frequency. With the help of electron channeling contrast imaging (ECCI) inside a scanning electron microscope (SEM), a relatively large area in the failed bulk specimen could be easily observed with high-resolution down to dislocation level. In this work, the dislocation sub-structure immediately under the fracture surfaces were investigated by ECCI to depict the difference in the plasticity evolution during fatigue crack growth (FCG). Based on the analysis, the H-enhanced FCG mechanisms were discussed.

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Fatigue crack non-propagation assisted by nitrogen-enhanced dislocation planarity in austenitic stainless steels

Cited by 14 publications

References 36 publications

Visualization of dislocations through electron channeling contrast imaging at fatigue crack tip, interacting with pre-existing dislocations

Visualization of dislocations through electron channeling contrast imaging at fatigue crack tip, interacting with pre-existing dislocations

Microstructural Crack Tip Plasticity Controlling Small Fatigue Crack Growth

Hydrogen-enhanced fatigue crack growth behaviors in a ferritic Fe-3wt%Si steel studied by fractography and dislocation structure analysis

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