Acquiring in situ Fatigue Crack Growth Curves by a Compliance Method for Micro Bending Beams to Reveal the Interaction of Fatigue Cracks with Grain Boundaries

Gruenewald, Patrick; Rauber, Jonas; Marx, Michael; Schaefer, Florian

doi:10.1016/j.prostr.2019.08.003

Cited by 8 publications

(4 citation statements)

References 19 publications

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“…The shown misorientations might not support that theory, which agrees with the findings of Gruenewald et al, who recently highlighted that is not suitable for detecting the crack growth resistance for stage-II fatigue cracks for cubic face centered. materials [28]. The detected not increased density of geometrical necessary dislocations (GND, Figure 11) might be not contractionary, due to the fact that the partition and contribution of statistical stored dislocations (SSD) might be enhanced due to the location of the MnS inclusions in the grains.…”

Section: Discussionmentioning

confidence: 95%

Performance-Related Characterization of Forming-Induced Initial Damage in 16MnCrS5 Steel under a Torsional Forward-Reverse Loading Path at LCF Regime

Moehring

Walther

2020

Materials

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Forming technology and in particular cold forward rod extrusion is one of the key manufacturing technologies with regard to the production of shafts. The selection of process parameters determines the global and local material properties. This particularly implies forming-induced initial damage in representation of pores. On this background, this study aims on describing the influence of these pores in the performance of the material 16MnCrS5 (DIN 1.7139, AISI/SAE 5115) under a torsional load path in the low cycle fatigue regime, which is highly relevant for shafts under operation conditions. For this purpose, the method of cyclic forward-reverse torsional testing was applied. Additionally, intermittent testing method and the characterization of the state of crack growth using selective electron microscopy analysis of the surface were combined. A first attempt was made to describe the influence of forming-induced initial damage on the fatigue performance and the crack growth mechanisms. The correlation of fatigue performance and initial damage was contiguous in the sense that the initial damage corresponds with a decrease of material performance. It was concluded that the focus of further investigations must be on small crack growth and the related material changes to identify the role of initial damage under cyclic loads.

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Section: Discussionmentioning

confidence: 95%

Performance-Related Characterization of Forming-Induced Initial Damage in 16MnCrS5 Steel under a Torsional Forward-Reverse Loading Path at LCF Regime

Moehring

Walther

2020

Materials

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“…Because the first one is decoupled from the obstacle interaction, we can use the crack growth curves from the single crystals and compare them with the grain boundary specimens. All bicrystalline specimens have a slope m short in the range of 9, whereas there were single crystalline specimens 20 with an m short of over 12. Taking a look at the crystal orientations, the grains where the cracks of the bicrystals initiated had a similar crystallographic orientation ( θ ~ 11°) with four slip systems having high and similar Schmid factors (<110> direction in beam axis), whereas the crystal orientation with the high slope had eight slip systems with a similar Schmid factor of the same magnitude as for the bicrystalline case (<100> direction in beam axis).…”

Section: Evaluation Of This Techniquementioning

confidence: 96%

“…The following chapter demonstrates the technique for two different grain boundary set‐ups. More examples of this method in use are presented in previous work 20 …”

Section: Application Example: Grain Boundariesmentioning

confidence: 99%

Fatigue crack growth in micro specimens as a tool to measure crack–microstructure interactions

Grünewald

Rauber

Marx

et al. 2020

Fatigue Fract Eng Mat Struct

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The process of short fatigue crack growth plays a significant role for the lifetime of materials in the high and very high cycle regimes. Fatigue crack growth is strongly influenced by interactions with microstructural obstacles, such as grain boundaries or phase boundaries, requiring a better understanding of these interactions to enhance the lifetime in these load regimes and improve lifetime calculations. Although it is possible to obtain crack growth rates from fatigue cracks in the lower micrometre range, further information like the exact position and type of the obstacle are mostly unavailable during the experiment. To overcome this issue, we propose a testing methodology of fatigue crack growth in micro specimens, which allows for an exact positioning of the crack relative to the obstacles and for monitoring the crack behaviour in a scanning electron microscope. The capabilities of this method are demonstrated for the interaction of fatigue cracks with grain boundaries.

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“…Nanomechanical testing approaches, such as micropillar compression, are well suited to access the quasi-static behavior of individual microstructural components [18][19][20]. However, only very few suitable techniques are yet available [21][22][23][24] for accessing their cyclic deformation behavior. A promising approach for local fatigue tests is the cyclic micropillar compression test, recently developed by Merle and Höppel [25].…”

Section: Introductionmentioning

confidence: 99%

Revealing the local fatigue behavior of bimodal copper laminates by micropillar fatigue tests

Krauß

Schieß

Göken

et al. 2020

Materials Science and Engineering: A

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Acquiring in situ Fatigue Crack Growth Curves by a Compliance Method for Micro Bending Beams to Reveal the Interaction of Fatigue Cracks with Grain Boundaries

Cited by 8 publications

References 19 publications

Performance-Related Characterization of Forming-Induced Initial Damage in 16MnCrS5 Steel under a Torsional Forward-Reverse Loading Path at LCF Regime

Performance-Related Characterization of Forming-Induced Initial Damage in 16MnCrS5 Steel under a Torsional Forward-Reverse Loading Path at LCF Regime

Fatigue crack growth in micro specimens as a tool to measure crack–microstructure interactions

Revealing the local fatigue behavior of bimodal copper laminates by micropillar fatigue tests

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