Morphological changes of graphite spheroids during heat treatment of ductile cast irons

Monchoux, Jean‐Philippe; Verdu, Catherine; Thollet, G.; Fougères, R.; Reynaud, A.

doi:10.1016/s1359-6454(01)00230-0

Cited by 33 publications

(40 citation statements)

References 9 publications

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“…Following research on graphene [22], it is suggested to call these individual plates structural base units (SBU). In the present observations, it was found they have a thickness between 10 and 100 nm, values which are similar to those reported by Miao et al [5] at 120 nm and Monchoux et al [20] at 100-1,000 nm for spheroidal graphite, but also by Double and Hellawell [13] at 100 nm for lamellar graphite.…”

Section: Resultssupporting

confidence: 92%

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Microstructural Characterization of Graphite Spheroids in Ductile Iron

Theuwissen

Lafont

Laffont

et al. 2012

Trans Indian Inst Met

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The present work brings new insights by transmission electron microscopy allowing disregarding or supporting some of the models proposed for spheroidal growth of graphite in cast irons. Nodules consist of sectors made of graphite plates elongated along a hai direction and stack on each other with their c axis aligned with the radial direction. These plates are the elementary units for spheroidal growth and a calculation supports the idea that new units continuously nucleate at the ledge between sectors.

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Section: Resultssupporting

confidence: 92%

“…2 shows a graphite nodule whose radius is about 10 lm. Within this nodule, dark areas are metallic particles containing Fe and Si as often observed [20]. The boundary between two sectors can be seen by the change in orientation of the contrast lines, e.g.…”

Section: Resultsmentioning

confidence: 63%

Microstructural Characterization of Graphite Spheroids in Ductile Iron

Theuwissen

Lafont

Laffont

et al. 2012

Trans Indian Inst Met

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“…The radial growth of the graphite conical crystals well seen in Figure 6 has been already observed using different microscopy techniques 14, 19, 26, 27. Here, for the first time it was possible to acquire high resolution images containing a nucleus in the center of the nodule.…”

Section: Resultsmentioning

confidence: 99%

Characterization of Graphite Crystal Structure and Growth Mechanisms Using FIB and 3D Image Analysis

et al. 2010

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Considering the significant influence of the morphology of graphite inclusions on the properties of cast iron it is important to understand the correlation between manufacturing parameters and resulting microstructure. In particular, understanding the effect of alloying elements and inoculants on the formation and growth mechanisms of the graphite particles provides the basis for exact tailoring of the microstructure and thus exact tailoring of effective properties of cast iron. Experimental observations of the three‐dimensional (3D) structure of graphite particles, high resolution chemical analysis of nuclei and other inclusions, as well as quantitative characterization of possible growth mechanisms have confirmed certain existing theoretical models for nodular and flake graphite and provided a comprehensive description of all intermediate morphologies. Precise analysis of the graphite's crystal structure based on target preparation of transmission electron microscope thin foils opens additional possibilities for estimating of the properties of different graphite types.

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“…As it is visible in Figure , the debonding revealed in the superficial layer of spheroid seemed to pass between small metallic particles embedded in a graphite spheroid (Figure a), and between insertions of the matrix visible on the bottom of the cavity remained after spheroid removing (Figure c). According to Dierickx et al () and Monchoux et al (), these small metal inclusions could be residuals of matrix, that were closed in spheroids near the G/M interface at the austenitization stage. On both complementary surfaces, this of the spheroid and that of the cavity, individual, branched graphene layers, partially separated from each other along the “c” direction, embedded between metal particles, have been revealed (Figure b, d).…”

Section: Resultsmentioning

confidence: 97%

“…Circumferential cracks (Figures ) usually appeared as a result of separation of individual shells inside graphite spheroid formed around the core during cooling and subsequent heat treatment, or through the carbon deposition at the G/M interface due to decreasing its solubility in solid solution (D'Agostino, Di Cocco, Fernandino, & Iacoviello, ; Iacoviello & Di Cocco, ). Another kind of superficial layer is formed due to a spheroid dissolution during the austenitization treatment (Figures ; Dierickx, Verdu, Reynaud, & Fougeres, ; Monchoux, Verdu, Thollet, Fougeres, & Reynaud, ). The path of the circumferential cracks usually observed in the examined spheroids was differentiated, especially in the ADI specimens after the heat treatment.…”

Section: Resultsmentioning

confidence: 99%

Microscopic approach to micromechanism of damage in spheroidal cast iron

Warmuzek

Polkowska

Gazda

2020

Microscopy Res & Technique

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In this work, the observations of the fracture surface after standard tensile tests of several kinds of spheroidal cast irons, ferritic and austempered ductile irons, have been carried out by means of scanning electron microscopy. The local crack path in the area of graphite (G)/matrix (M) interface has been analyzed as affected by a matrix phase composition and the austempering treatment parameters. The obtained results allowed identifying some determination factors for debonding mode at the G/M interface and their role in a final damage mechanism. Some microstructural details in the microregions composed of graphite and matrix showed that the G-M debonding mode in the separation area of the G/M interface seems to be controlled by macroscopic properties of the alloy and by the morphology of G/M interface. On the other hand, the internal destruction of graphite nodule has been mainly determined by a structure and anisotropy of graphite crystal lattice. K E Y W O R D S characterization, electron microscopy, fracture behavior, iron alloys

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Morphological changes of graphite spheroids during heat treatment of ductile cast irons

Cited by 33 publications

References 9 publications

Microstructural Characterization of Graphite Spheroids in Ductile Iron

Microstructural Characterization of Graphite Spheroids in Ductile Iron

Characterization of Graphite Crystal Structure and Growth Mechanisms Using FIB and 3D Image Analysis

Microscopic approach to micromechanism of damage in spheroidal cast iron

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