Optical in situ investigations of overload effects during fatigue crack growth in nodular cast iron

Zybell, Lutz; Chaves, H.; Kuna, Meinhard; Mottitschka, T.; Pusch, G.; Biermann, Horst

doi:10.1016/j.engfracmech.2012.01.006

Cited by 19 publications

(9 citation statements)

References 24 publications

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“…On the microstructural level debonded graphite particles and secondary cracks were found in front of the crack tip. Later, Zybell et al [132] identified these effects as the start of ductile crack initiation, which are accompanied by the evolution of a large plastic zone, crack branching, and early stages of ductile crack growth. The same microstructural characteristics were found in pearlitic NCI, where multiple overloads resulted in a much more tortuous crack path than that of a normal fatigue crack [61].…”

Section: Fatigue Crack Growthmentioning

confidence: 98%

Micromechanisms of fracture in nodular cast iron: From experimental findings towards modeling strategies – A review

Hütter

Zybell

Kuna

2015

Engineering Fracture Mechanics

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Section: Fatigue Crack Growthmentioning

confidence: 98%

Micromechanisms of fracture in nodular cast iron: From experimental findings towards modeling strategies – A review

Hütter

Zybell

Kuna

2015

Engineering Fracture Mechanics

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“…102 The low strength associated with graphite particles makes them mechanically equivalent to defects or holes, 104 and the fatigue crack growth mechanism in cast iron changes due to the presence of chunky graphite. With spheroidal graphite morphology, cracks usually grow through the matrix trans-granularly passing around the graphite nodules and following the graphite-matrix interface 84,[105][106][107][108][109] (Figure 41). 74 In contrast, cracks penetrate into agglomerates of interconnected chunky graphite, thus tracking weak areas with high graphite concentration 92,93,102 (Figure 42).…”

Section: Fatigue Limit and Fatigue Crack Growth Ratementioning

confidence: 99%

Chunky Graphite in Ferritic Spheroidal Graphite Cast Iron: Formation, Prevention, Characterization, Impact on Properties: An Overview

Baer

2019

Inter Metalcast

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Ferritic spheroidal graphite cast iron (SGI) materials have a remarkable technical potential and economic impact in modern industry. These features are closely related to the question of how the cast materials can be produced without structural defects and graphite degenerations such as, for example, chunky graphite. Although the chunky graphite degeneration superficially seems to be well known, its metallurgical background is still controversially discussed, appropriate field-tested nondestructive tools for its quantification in castings are lacking, and the knowledge on its impact on material properties is fairly limited. Addressing this status, the article is providing a current overview on the subject. Existing theories on formation and growth mechanisms of chunky graphite are briefly reviewed. Furthermore, from a metallurgical point of view, causes for the appearance of chunky graphite as well as preventive measures are concisely summarized. Particular attention is paid to the morphology of chunky graphite and how it can be characterized by destructive and nondestructive techniques. Special emphasis was laid on providing a comprehensive overview on the impact of chunky graphite on strength, ductility, fatigue limit, fatigue crack growth rate as well as fracture toughness of ferritic SGI materials based on experimental data. Moreover, conclusions for the assessment of castings affected by chunky graphite are drawn.

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“…This can be attributed to the sudden increase in the number of fractured particle due to the damage produced by overloads, which facilitates the crack propagation. Zybell et al [46] and Hubner et al [47] ) in nodular cast iron and they attributed this behavior to the debonding of graphite particles from the matrix due to the damage produced by the overload. In our case, damage took place by fracture of SiC particles ahead of the crack tip at high K max (high R-ratio).…”

Section: à6â10mentioning

confidence: 99%

Fatigue crack growth in SiC particle reinforced Al alloy matrix composites at high and low R-ratios by in situ X-ray synchrotron tomography

Hruby

Singh

Williams

et al. 2014

International Journal of Fatigue

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a b s t r a c tMetal matrix composites (MMCs) offer high strength, high stiffness, low density, and good fatigue resistance, while maintaining cost an acceptable level. Fatigue resistance of MMCs depends on many aspects of composite microstructure. Fatigue crack growth behavior is particularly dependent on the reinforcement characteristics and matrix microstructure. The goal of this work is to obtain a fundamental understanding of fatigue crack growth behavior in SiC particle-reinforced 2080 Al alloy composites. 'In situ X-ray synchrotron tomography was performed on two samples at low (R = 0.1) and at high (R = 0.6) R-ratios. The resulting reconstructed images were used to obtain three-dimensional (3D) rendering of the particles and fatigue crack. Behaviors of the particles and crack, as well as their interaction, were analyzed and quantified. Four-dimensional (4D) visual representations were constructed to aid in the overall understanding of damage evolution.

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Optical in situ investigations of overload effects during fatigue crack growth in nodular cast iron

Cited by 19 publications

References 24 publications

Micromechanisms of fracture in nodular cast iron: From experimental findings towards modeling strategies – A review

Micromechanisms of fracture in nodular cast iron: From experimental findings towards modeling strategies – A review

Chunky Graphite in Ferritic Spheroidal Graphite Cast Iron: Formation, Prevention, Characterization, Impact on Properties: An Overview

Fatigue crack growth in SiC particle reinforced Al alloy matrix composites at high and low R-ratios by in situ X-ray synchrotron tomography

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