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On the Morphology Variation of Graphite in Ductile Cast Iron …

2.1 Melting and Sample Preparation. In this research, experimental ductile iron with a specific chemical composition (as shown in Table 1) was produced using an induction furnace, following the guidelines of ASTM E351 [].The melt was prepared based on ASTM A536 [] for SG40 cast iron, and FeSiMg alloy was introduced into the molten metal at a temperature of …

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Nucleation and growth of graphite particles in ductile cast iron

There are several theories to explain the nucleation and growth mechanism of graphite in cast iron, and certain researchers propose that the magnesium added through the …

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Graphite Floatation In Ductile Irons

On the Morphology Variation of Graphite in Ductile Cast … 2.1 Melting and Sample Preparation. In this research, experimental ductile iron with a specific chemical composition (as shown in Table 1) was produced using an induction furnace, following the guidelines of ASTM E351 [].The melt was prepared based on ASTM A536 [] for SG40 cast iron, and FeSiMg alloy was introduced …

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Promising energy-storage applications by flotation of graphite …

Graphite ore is a mineral exclusively composed of sp 2 hybridized carbon atoms with p-electrons, found in metamorphic and igneous rocks [1], a good conductor of heat and electricity [2], [3] with high regular stiffness and strength. Note that graphite (plumbago) can maintain its hardness and strength at a temperature of up to 3600 °C [4].Its layers structure …

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Morphologies of Some Graphites in Ductile Cast Irons

Spheroidal and vermicular graphite were observed in the ductile cast iron with spheroidizing treatment. Flake graphite was observed in the same cast iron without the spheroidizing treatment. The spheroidal graphite had a three-fold internal structure, with an amorphous-like central region, annual rings of a layered intermediate region, and an outer

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Offsetting shrinkage in Ductile Iron ver 2

Graphite is a hexagonal-closepack form of carbon that can grow in both the liquid and solid forms of iron. In theory, in irons above the eutectic composition of carbon, the graphite first nucleates in the liquid, and then continues to grow in the solid. In irons below the eutectic composition, the graphite does not start

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(PDF) Shrinkage in Ductile Cast Irons: Effects Explored

As a matter of fact, hypereutectic cast irons are commonly employed with however some limitations in case of heavy-section castings where some graphite flotation should be avoided. The results obtained in the present work show an optimal composition for minimising shrinkage that corresponds to slightly hypereutectic alloys.

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Microstructural Characterization of Graphite Spheroids in Ductile …

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 〈a〉 direction and stack on each other with their c axis aligned with the radial direction. These …

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A Review of Dendritic Austenite in Cast Irons

It was early suggested that the spheroidal graphite of ductile irons grows predominantly outside of the coupled zone. 3 It has later been proposed that ductile irons do not have a coupled zone; 51 however, this is disputed by observations of chunky graphite in slowly cooled ductile irons, featuring finer graphite morphologies growing coupled ...

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Solidification, Macrostructure and Shrinkage Formation of Ductile …

This manuscript summarizes recent investigation of the authors into the solidification and shrinkage defect formation of ductile and compacted graphite cast irons. The study makes use of the DAAS (direct austempering after solidification) technique, developed earlier by some of the authors, to reveal the solidification grains. In addition, color metallography is used to reveal …

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EFFECT OF INOCULATION ON THE FORMATION OF …

Chunky graphite is one of the most deleterious graphite degenerations in thick-walled ductile-iron castings. This defect normally appears in the thermal center of a casting and dramatically …

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nodular ductile iron

The advantage of austempering is that it results in ductile irons with twice the tensile strength for the same toughness. Compacted graphite (CG) irons have a graphite shape intermediate between spheroidal and flake. Typically, compacted graphite looks like type IV graphite.

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Graphite Flotation

Carbon flotation in ductile iron is caused when the foundry allows the Carbon Equilivant to exceed the ability of the magnesium to suppress graphite formation in the liquid. My experience suggests that limit is about 4.55 - 4.60 with moderate levels of …

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EFFECT OF INOCULATION ON THE FORMATION OF …

Chunky graphite, CHG, is one of the most deleterious graphite degenerations in thick-walled ductile-iron cast-ings. CHG normally appears in the thermal center of large castings, and decreases the mechanical properties, in particular the tensile and fatigue strength and elonga-tion. Local, cell-type accumulations of compact graphite

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Review of Microstructural Features of Chunky Graphite in …

2013 Keith Millis Symposium on Ductile Cast Iron Review of Microstructural Features of Chunky Graphite. in Ductile Cast Irons. J. Lacaze CIRIMAT, Université de Toulouse, Toulouse, France

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[PDF] A Possible Mechanism for the Formation of Exploded Graphite …

In hypereutectic nodular cast irons, primary precipitation of graphite may lead to graphite flotation in thick section castings. Graphite degeneracy such as so-called exploded graphite is then often associated with this flotation phenomenon and it appears as precipitates where the nodular form is replaced by star-like or flower-like shape. It has been reported that exploded graphite …

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A Review of Common Metallurgical Defects in Ductile Cast Iron

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Formation of Ultrafine Graphite Nodules in Ductile Iron and its …

The evolution of ductile iron with martensitic matrix during annealing at 700 °C was studied in the present study. The results showed that the ultrafine graphite nodules with a count of 8500 nod/mm2 and an average diameter of about 1 µm were obtained in ductile iron through annealing treatment. The martensite in ductile iron was first decomposed into granular …

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Precipitation and evolution of nodular graphite during solidification

The quantity and morphology of spheroidal graphite have an important effect on the properties of ductile iron, and the characteristics of spheroidal graphite are determined by the solidification process. The aim of this work is to explore the precipitation and evolution of graphite nodules in hypoeutectic, eutectic, and hypereutectic ductile irons by thermal analysis, liquid …

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Graphite Floatation In Ductile Irons

The Roundness Graphite Shape Factor (RSF), which is considered (by the international standard ISO 945-4-2019) to characterize the representative graphite morphologies in cast irons (Figure 3 b), suggests a fall within the slightly irregular spheroidal graphite (Form V ISO 945), in the 4.5%Si ductile cast iron test.

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Chunky graphite formation in ductile cast irons: effect of …

Sertucha, Jon Chunky graphite formation in ductile cast irons: effect of silicon, carbon and rare earths . (2016) International Journal of Materials Research, vol. 107 (n° 11). pp. 1041-1050. ISSN 1862-5282 Any correspondence concerning this service should be sent to the repository

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Relationship between cooling rate and microsegregation in …

BOTTOM-CHILLED DIRECTIONALL Y SOLIDIFIED DUCTILE IRONS. W.S. Chang a, C.M. Lin a, b, * ... This study has been conducted to better understand the phenomenon of graphite flotation in cast irons. It ...

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Graphite flotation

Graphite flotation must not be mistaken for kish graphite (q. v.) occurring in flake graphite cast iron. Flotation of graphite influences expansion and contraction of the cast iron during eutectic solidification and thus also interferes with seal …

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ggg40

But frequenttly the range of equivalent carbon is 4,2 to 4,4% because the graphite flotation and to the casting soundness this relation is a good information ... I too was relating it to grey iron casting. Infact GG series is now grey iron and GGG is related to ductile irons. I have reproduced an extract in German giving mechanical properties ...

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A Review of Common Metallurgical Defects in Ductile Cast Iron …

Indeed, the ductile iron foundry, which truthfully claims not to have shrinkage concerns is the exception to the rule. Other common defects may be divided into two basic categories: -Those related to nodule shape and size, such as compacted graphite structures, exploded and chunky graphite, graphite floatation, spiky graphite and nodule alignment.

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Graphite Nodularity Evaluation in High-Si Ductile Cast Irons

The Roundness Graphite Shape Factor (RSF), which is considered (by the international standard ISO 945-4-2019) to characterize the representative graphite morphologies in cast irons (Figure 3b), suggests a fall within the slightly irregular spheroidal graphite (Form V ISO 945), in the 4.5%Si ductile cast iron test. For RSF < 0.7, it practically ...

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A Possible Mechanism for the Formation of Exploded …

In hypereutectic nodular cast irons, primary precipitation of graphite may lead to graphite flotation in thick section castings. Graphite degeneracy such as so-called exploded graphite is then often associated with this flotation phenomenon and …

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graphite floating of ductile cast iron

Because the density of graphite is lower than that of molten iron, the graphite floats to the upper part of the casting under the drive of magnesium vapor. The higher the carbon equivalent, the more serious the graphite floating …

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Formation mechanism of chunky graphite in heavy …

The nucleation and growth behaviour of chunky graphite in heavy section ductile cast irons was studied. The microstructure in the quenched samples during solidification was observed using optical ...

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3. Common Metallurgical Defects in DI

Ultraseed® inoculant is designed for pure Mg produced ductile iron, irons of low oxygen and sulphur levels and dead iron which has been held for extended periods of time. This inoculant will give high nodule counts in ductile iron which is normally difficult to inoculate and will help to prevent micro-shrinkage. Chunky Graphite Potential Causes:

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