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As discussed earlier for metamorphic graphite, helical growth can lead to the formation of holes in the middle of graphite aggregates. This is illustrated in Fig. 11-b for the case of chunky graphite. Growth through the foliated dendrites mechanism is also shown in Fig. 11-c for a different region of the chunky graphite.
have appeared during bulk eutectic reaction.Furthermore, it becomes visible that chunky graphite as well as exploded graphite in the SG -PbCe alloy are located in areas first solidified (Figs. 3 ...
out by the later finding that chunky graphite grows interconnected.29 2. Liu et al.30 proposed a helical growth mechanism where chunky graphite is composed by a series …
exploded or chunky graphite could appear. It has been con-firmed in Reference 39 that Ce can basically compensate the. detrimental effect of Pb on the graphite morphology. Indi-
Chunky graphite (CHG) is a well-known phenomenon which occurs in heavy section spheroidal graphite iron (SGI) castings or SGI castings with higher alloying content. Chunky graphite results in a decrease of mechanical properties, in particular a decrease in elongation. Despite numerous studies, the root cause of the CHG formation remains ...
While the specialists almost unanimously claim that avoidance of chunky graphite in heavy sections cannot yet be rated a hundred percent process safe, 2,6,7,[13][14] [15] [16][17][18][19][20] a ...
A: Chunky graphite is an abnormal form of graphite commonly associated with heavy-section ductile iron casting(s), i.e., areas having a section thickness greater than 50 mm. These "last-to-solidify" sections of a casting are the most susceptible to this form of degenerative graphite, including the area located under a riser as this feed ...
This paper investigates the effects of silicon content above 3 wt% and different cooling rates on the graphite morphology and the mechanical properties of ductile cast iron. To research and determine these effects, three grades of high-silicon ductile iron were cast with silicon content of 3 wt%, 3.5 wt% and 4.5 wt%. In order to investigate the …
Microstructure shows variation in the graphite structure from nodular to chunky and at some locations exploded graphite. The Carbon Equivalent is 4.783% which indicates towards hyper-eutectic side, this is one of the strong reasons for the formation of chunky and exploded graphite.
Chunky graphite morphology negatively affect the mechanical properties of cast iron due to undercooling and presence of trace elements. Sertucha et al. showed the eutectic undercooling versus growth rate for chunky graphite (CHG) and nodular graphite (spheroidal) in a recent publication. From this figure it is seen that chunky graphite …
1 Chunky Graphite in Low and High Silicon Spheroidal Graphite Cast Irons–Occurrence, Control and Effect on Mechanical Properties Jon Sertucha 1,*, Garikoitz Artola 1, Urko de La Torre 1 and Jacques Lacaze 2,* 1 Azterlan, Basque Research Technological Alliance, Aliendalde Auzunea 6, 48200 Durango, Spain; [email protected] (G.A.); …
indications of exploded graphite can be observed. The graphite nodule count amounts to 156 mm-2. The microstructure in Figure 4b shows, besides almost per-fectly formed graphite spheroids, lamellar outgrowths from the graphite spheroids as well as intergranular flake gra-phite. This is a typical form of graphite degeneration
Chunky graphite (CHG) is certainly one of the most deleterious graphite degeneracy in ductile cast irons used in manufacturing heavy-section parts. This defect normally appears on cut or machined ...
Chunky graphite (CHG) is a well-known phenomenon which occurs in heavy section spheroidal graphite iron (SGI) castings or SGI castings with higher alloying …
In the first group are chunky graphite (CHG) and exploded graphite (EG) whereby EG is an intermediate between regular nodular graphite and CHG. 7, 8 Intercellular lamellar graphite (ILG ...
Abstract Use of rare earths, high silicon and carbon contents, and low cooling rates are reported as possible reasons for formation of chunky graphite in ductile iron castings. The understanding of this graphite degeneration is however limited, and the above conclusions are still controversial. To get further insight into this topic, ductile cast …
Ferritic spheroidal graphite cast iron (SGI) materials have a remarkable technical potential and economic impact in modern industry. …
chunky graphite but also lead to some spiky graphite when no rare earth is added. Chunky graphite negatively a ects the room temperature mechanical properties, though much more in the case of low silicon spheroidal graphite cast irons than in high silicon ones. Spiky graphite has been found to be much more detrimental and should thus be …
eutectic growth, which results in exploded or even chunky graphite. Possible reasons are long solidification times, high amounts of Si and the presence of Ce in the melt.1
That fewer and larger nodules are more prone to degenerate is well known, this has been recently evidenced by X-ray computerized tomography (4D-XCT) [24] and theorized for the case of exploded ...
The conical sectors may occupy the whole volume of the sphere forming a graphite spheroid, or only part of it like in exploded graphite. Chunky graphite can be the product of a succession of conical sectors growing on top of one another. Before concluding we need address one more issue. Many SEM pictures of SG iron exhibit a layer growth ...
lamellar graphite can be prevented, whereas by exceeding a critical amount of Ce exploded and chunky graphite will be formed [2]. There are different investigations about critical amounts of trace elements affecting graphite morphology in ductile cast iron as reviewed by Reynaud [3]. Buhr [2] reported that already small
Different mechanisms have been proposed for the formation of exploded graphite. Considering that nodularizers facilitate nucleation into basal planes with growth mainly occurring in the prismatic ...
A Review of Common Metallurgical Defects in Ductile Cast Iron – …. Ductile Cast Iron Causes and Cures C.M.Ecob Customer Services Manager, Elkem AS, Foundry Products Division Abstract …exploded and chunky graphite, … » Free online chat! Material, AutoCad and Fun: Common Defects in Ductile Cast Iron. Feb 12, 2009 · … an overview …
Shape stabilized phase change materials based on different support structures for thermal energy storage applications–A review. Veerakumar Chinnasamy, ... Honghyun Cho, in Energy, 2023. 2.3.2 Expanded graphite (EG). Expanded graphite is a layered structure of graphite with interlayer space. PCM can be filled in these interlayer spaces and pores, …
Regarding unclassified graphite morphologies like exploded, chunky or spiky graphite, the need to identify and quantify these was stressed by the survey participants. Visual Classification of Individual Graphite Particles. For each particle, the different assignments (graphite classes, degenerated graphite form or other) were …
inclusions while the larger cubes had chunky graphite. Chunky graphite morphology negatively affect the mechanical properties of cast iron due to undercooling and …
The spheroidal graphite present in the ductile iron assures the excellent mechanical properties, while the chunky graphite significantly reduces those properties of the ductile iron.
Etching. 3% Nital. Chunky graphite is a degenerate form of spheroidal graphite, so this casting should have been a spheroidal graphite casting (probably around GJS400). The appearance corresponds to an …
Chunky graphite appears easily in heavy-section spheroidal graphite cast irons and is known to affect their mechanical properties. A dedicated experiment has been developed to study the effect of the most important chemical variables reported to change the amount of chunky graphite, namely the content in silicon and in rare earths. Quite …
Silicon is one of the elements that tend toward chunky graphite formation. By comparing the effect of Si and Ni on chunky graphite in heavy castings (micro/macro analysis), it was found that higher Si has a strong influence on chunky graphite formation, especially in castings with a slow cooling rate, while Ni promotes chunky graphite only …
Chunky graphite is branched and interconnected as a network within eutectic cells and has been observed to form in thermal centres of heavy ductile cast iron sections during solidification. This research work proved that chunky graphite in the microstructure decreases the ultimate tensile strength, the elongation to fracture and fatigue life ...
Graphite formation in the solid state is both in ductile cast irons and in steels strongly promoted by high silicon contents above 3 wt.% Si. The matrix microstructure in austempered ductile iron can be further refined by secondary graphite if the austenitization, quench, and isothermal transformation into ausferrite are preceded by an austenitization …