On the blocking effect of grain boundaries on small crystallographic fatigue crack growth

Zhang, Yan Hui; Edwards, L.

doi:10.1016/0921-5093(94)90363-8

Cited by 36 publications

(6 citation statements)

References 21 publications

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“…Several torsion cracks with a crack direction parallel to the orientation of the maximum shear stress are shown in Figure 13b. The cracks are inhibited by microstructural barriers, namely the orientation of the surrounding grains, which conforms to other researcher findings [2,7,13].…”

Section: Sem Observationssupporting

confidence: 91%

“…The fatigue life of the material is determined from the microstructure, grain conditions, and crystal orientation. Grain boundaries are an obstacle to microcracking [6,7,13]. The possibility of a microcrack continuing to propagate is determined, among other things, by the orientation of the surrounding crystals and grains.…”

Section: Crack Researchmentioning

confidence: 99%

“…To explain the crack propagation across this grain boundary, several models were developed. Zhang [13] stated that cracks prefer to propagate along slip systems with high Schmidt factors when transferring from one grain to another. The Schmidt factor is defined as the ratio of the resolved shear stress on a certain slip system to the applied stress.…”

Section: Introductionmentioning

confidence: 99%

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On the Influence of the Initial Shear Damage to the Cyclic Deformation and Damage Mechanism

Suhartono¹,

Kirman²,

Prawoto³

2022

Metals

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The accuracy and precision of lifetime predictions for cyclically loaded technical components are still lacking. One of the main reasons for the discrepancy between the calculated life time and experimental results is that it is not yet possible to create a model capable of describing the microstructural damage process that occurs in the tested material and to subsequently incorporate this model into the calculation. All of the presently available research results recognize that the growth of microcracks is significantly influenced by the microstructure of the material. In order to take into account the influence of the microstructure on the damage process, research on the very early fatigue damage is carried out. The results are obtained from tension and torsion fatigue testing. For this purpose, the surfaces of the tested specimens are carefully observed to discover and analyze microcracks, which are classified according to their orientation. Moreover, the mechanisms of crack initiation and propagation are major points of interest. Through a mix of mechanical and metallurgical points of view, calculations and multi-level FEA modeling are carried out to gain a better understanding of the properties of the phases. The simulation is based on continuum mechanics, which considers the positions and mechanical metallurgy, which account for each constituent character’s failure laws. It is concluded that both the experimental and computational approaches conform, showing that such an approach is indeed a necessity and should become a trend in the near future. Statistically, microcracks under tension modes are highest at 45° (approximately 30%), while under torsion they are highest at 0° (approximately 20%) with respect to the sample orientation. The influence of the microstructure is explained via the finite element analysis.

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Section: Sem Observationssupporting

confidence: 91%

Section: Crack Researchmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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On the Influence of the Initial Shear Damage to the Cyclic Deformation and Damage Mechanism

Suhartono¹,

Kirman²,

Prawoto³

2022

Metals

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“…9 In high cycle fatigue, the grain boundaries play a more crucial role in controlling the path and propagation rate of short cracks during the microstructure-sensitive stage. [9][10][11][12] It was recently reported that the propagation direction of fatigue cracks within the facet observed at the crack initiation site changes from inclined to horizontal due to the effect of grain boundaries in martensitic stainless steel. 13 As a result, the inclined crack path appears in numerous dispersed small regions with roughly equal sizes to the grain diameter, and it exhibited a relatively rough area around the crack initiation site.…”

Section: Introductionmentioning

confidence: 99%

Effect of microstructure and local stress on small crack initiation and propagation paths in coarse‐grained FeCrAl alloys

Zhan,

Liu,

Dai

et al. 2023

Fatigue Fract Eng Mat Struct

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This study investigated the high cycle fatigue crack initiation and propagation behaviors in coarse‐grained FeCrAl alloys, with a focus on the relationship between the path of small cracks and the local microstructure. The results show that the small cracks initiate along the {100} slip plane due to the synthetical influence of local microstructure and shear stress. The initiation zone forms inclined areas with layered fine‐grain areas caused by cyclic shear stress. Quantitative analysis of the stress intensity factor (SIF) indicates that in the realm of mixed‐mode loading, the SIF of Mode I takes the lead in determining the intensity of stress and strain fields at the crack tip. As the crack propagates further, the SIF steadily increases. Once it reaches a specific threshold, the propagation mode within a coarse grain shifts from Mode II to Mode I. Moreover, fatigue life increases with a tendency for decreased SIF during crack deflection.

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“…[1][2] [3]. It has been noted for example that the crack growth rate can be decreased when the crack approaches the grain boundary [3][4] and [5]. Also, short cracks tend to closely follow the slip plane.…”

Section: Introductionmentioning

confidence: 99%

The Influence of the Grain Structure Size on Microstructurally Short Cracks

Simonovski

Cizelj

2009

Journal of Engineering for Gas Turbines and Power

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The dominant processes in the initialization and propagation of microstructurally short cracks include microstructural features such as crystallographic orientations of grains, grain boundaries, inclusions, voids, material phases, etc. The influence of the microstructural features is expected to vanish with distance from the crack tip. Also, the influence of the nearby microstructural features is expected to be smaller for a long than for a small crack. Finally, a crack of sufficient length can be modeled using classical fracture mechanics methods. In this paper the approach to estimate the crack length with vanishing influence from the microstructural feature is proposed. To achieve this, a model containing a large number of randomly sized, shaped and oriented grains is employed. The random grain structure is modeled using a Voronoi tessellation. A series of cracks of lengths from about 1 to 7 grain lengths are inserted into the model, extending from a grain at the surface towards the interior of the model. The crack tip opening displacements (CTOD) are estimated and statistically analyzed for a series of random crystallographic orientation sets assigned to the grains adjacent to the crack. Anisotropic elasticity and crystal plasticity constitutive models are employed at the grain size scale.It is shown that the standard deviation of the crack tip opening displacement decreases from about 20% for a short surface crack embedded within a single grain to about 7 % for a surface crack extending through 7 grains. From the engineering point of view, a crack extending through less than about 10 grains sizes is therefore considered to strongly depend on the neighboring microstructural features.

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On the blocking effect of grain boundaries on small crystallographic fatigue crack growth

Cited by 36 publications

References 21 publications

On the Influence of the Initial Shear Damage to the Cyclic Deformation and Damage Mechanism

On the Influence of the Initial Shear Damage to the Cyclic Deformation and Damage Mechanism

Effect of microstructure and local stress on small crack initiation and propagation paths in coarse‐grained FeCrAl alloys

The Influence of the Grain Structure Size on Microstructurally Short Cracks

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