The importance of melt chemistry on graphite shape is well known, and the effect of impurities or alloying elements on the change from spheroidal to chunky graphite at given growth conditions is ...

Although the chunky graphite degeneration superficially seems to be well known, its metallurgical background is still controversially discussed, appropriate field-tested nondestructive tools for ...

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 of clustered, sector-shaped graphite segments. Branching is ascribed to microsegregation of certain elements like cerium and others. Chunky graphite is characterized as a ...

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 iron …

The difference between graphitic steel and ferritic ductile iron is the size and amount of graphite nodules, 5 µm versus 20–50 µm in size and 2 vol.% versus 10 vol.% of graphite. However, size seems to be a minor factor in machinability. Katayama and Toda reported equal machinability for dispersions of 5 µm or 10 µm.

Exploded graphite, mainly due to an excess of rare earth additions, Fig. 1; Chunky graphite, due to an excess of rare earth additions, Fig. 2; Compacted graphite, mainly due to low residual ...

chunky graphite,2,3 the special importance of destructive ... exploded or chunky graphite (CHG).21 This illustrates the complexity of graphite crystallization and growth in iron melts. Con-

Chunky graphite negatively affects the room temperature mechanical properties, though much more in the case of low silicon spheroidal graphite cast irons than in high silicon …

According to [12–14], the 3.5% Si ductile iron showed good nodularity. In contrast, with increasing silicon content to 4.5%, significant graphite degeneracy occurred, with the …

Antimony is used in ductile cast iron melts to avoid graphite degenerations like exploded graphite and chunky graphite. However, the effect of Sb in the melt on the crystallization of ductile cast … Expand. 8. PDF. Save. Recent Developments in Understanding Nucleation and Crystallization of Spheroidal Graphite in Iron-Carbon-Silicon Alloys.

Abstract: Chunky graphite appears easily in heavy-section spheroidal graphite cast irons and is known to a ect their mechanical properties. A dedicated experiment has been developed to study the ... [24] and theorized for the case of exploded graphite [25]. Finally, using the fact that chunky graphite precipitates during coupled …

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 ...

Fig. 2. Pattern of Casting. Melting was realised in the medium-frequency inductive furnace with the acidic lining with the volume of 10 ton. As the charge used was the steel scrap (SVa), pig iron ...

Understanding spheroidal graphite growth in cast irons is a long standing problem for which several mechanisms have been proposed. During the last decade, observations using transmission electron microscopy added new information about the stacking of graphite layers, leading eventually to propose other mechanisms than …

Pb containing sample graphite spheroids as well as intergranular lamellar graphite have been found. At the same location of the casting containing both Pb and Ce, exploded as …

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-b and 3-d), whereas the intergranular flake graphite in the SG-Pb alloy can be found in the last to freeze regions (Figs. 3-a and 3-c). Also, in sample SG-Pb, lamellar outgrowths from graphite ...

Antimony is used in ductile cast iron melts to avoid gra-phite degenerations like exploded graphite and chunky graphite. However, the effect of Sb in the melt on the crystallization of ductile cast iron is still unknown, there-fore the aim of our investigations. The current study pre-sents thermodynamic calculations showing that at the ...

Using GD-OES (Glow Discharge Optical Emission Spectroscopy) investigation of macro segregation was made, comparing nodular and chunky graphite areas within the same 200 mm cubic block. Measurements were made in up to six positions located 10, 20, 30, 45, 60 and 90 mm from the cast surface. The analyzed positions are indicated in Figure 1.

Exploded graphite, mainly due to an excess of rare earth additions, Fig. 1; Chunky graphite, due to an excess of rare earth additions, Fig. 2; Compacted graphite, mainly due to low residual ...

Graphite Nodularity (NG3), calculated with the ISO 945-4-2019 [DI] formula, but replacing RSF with SSF, Sphericity Graphite Shape Factor, has an intermediary position. ... (spiky graphite), exploded …

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 decreases the mechanical properties. Chunky-graphite formation is primarily caused by a reduction in the cooling rate and melt composition.

Antimony is used in ductile cast iron melts to avoid graphite degenerations like exploded graphite and chunky graphite. However, the effect of Sb in the melt on the crystallization of ductile cast iron is still unknown, therefore the aim of our investigations. The current study presents thermodynamic calculations showing that at the beginning of the eutectic …

Abstract and Figures. Antimony is used in ductile cast iron melts to avoid graphite degenerations like exploded graphite and chunky graphite. However, the effect of Sb in the melt on the ...

The followings were confirmed in this study. (1) Exploded graphite appears when RE contents are above 0.02 mass%. (2) Chunky graphite does not appear when the Sb/RE ratio is above 0.7. The cause of the chunky graphite appearance will be studied next. 21 refs., 5 figs., 4 tabs.

Type IV: Predominant in compacted graphite iron, evaluated by the percentage of Types I and II observed. Type V: Spiky graphite form occasionally seen in ductile iron with Types I and II. Type VI: Exploded nodule graphite form occasionally seen in ductile iron with Types I and II. Type VII: Flake graphite form usually seen in gray …

In the thermal centre of the Pb containing sample graphite spheroids as well as intergranular lamellar graphite have been found. At the same location of the casting containing both Pb and Ce, exploded as well as chunky graphite could be observed, while the formation of intergranular lamellar graphite has been suppressed.

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 ...

Chunky graphite has been a phenomena encountered and studied since the invention of ductile iron in 1948. Still chunky is confused or mixed with other graphite forms such as …

Antimony is used in ductile cast iron melts to avoid gra-phite degenerations like exploded graphite and chunky graphite. However, the effect of Sb in the melt on the crystallization of ductile ...