In the studies of Méndez et al., 38 it was also verified that cast irons with 5.21 wt% Si presented degenerated graphite, identified as chunky graphite by the authors. 7,15,[39][40][41] [42] [43 ...
phite degenerations like exploded graphite and chunky graphite. However, the effect of Sb in the melt on the ... avoid the formation of chunky graphite. Even in ductile cast irons without any Ce ...
Graphite structures formed during the cooling of molten cast irons and during their solidification were examined in alloys as a function of composition, treatment (magnesium and/or rare earths) and inoculation. The effect of cooling rate and solidification conditions on the morphology of the resultant graphite was investigated using a variety of techniques …
Graphite Flotation Potential causes; High carbon equivalent. Excess pouring temperature. Slow cooling rate in thicker sections. Insufficient inoculation. Exploded Graphite Chunky Graphite Spiky Graphite Cause;· Excess rare earth additions, particularly when high purity charges are used. Normally found in thick section castings or at higher ...
Low S grey irons and ductile irons treated with high RE FSM reduce effectiveness. CHOICE OF INOCULANTS - OUR ADVICE Grey iron Πladle -1 % Sr or 2% Ba. ... Exploded Graphite Nodules Stereoscan X320 Inoculated- 20 mins later Underinoculated ductile iron 100 etched. 55th Indian Foundry Congress 2007
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 ...
Flotation of hypereutectic nodules occurs in ductile irons having carbon equivalents greater than 4.5 as defined by the expression CE = C% + (Si% / 3) + (P% / 3). ... including "cauliflowered" and exploded nodules and chunky graphite. The undesirable forms become increasingly prevalent as the extent of flotation, section size and casting ...
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 since this feed ...
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
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 ...
interconnected particles, known as chunky graphite (CHG), spiky, exploded, and compacted graphite are ... While a great effort was spent in the past in order to characterize the traditional ductile irons with ferritic and/or pearlitic matrices, limited data is available in technical papers regarding the new generation ductile irons (SSF-DI) [14 ...
These cast irons could also include other unwanted graphite morphologies, such as degenerated form (spiky graphite), exploded graphite, chunky graphite, etc. In comparison to steel, while there is no …
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 ...
Spheroidal graphite cast irons (SGCIs) have been widely used in automotive and energy industries requiring excellent mechanical strength and wear …
Shrinkage porosity or volume deficiency in ductile iron castings manifests itself in many different physical shapes and sizes. The terminology used to describe the various forms of shrinkage confuses operating personnel when they try to solve the problems. There is also confusion as to the use of thermal analysis events in estimating …
Iron Types (page 1), Gray & Ductile Irons. Home > Iron Types (page 1), Gray & Ductile Irons. Cast Iron Grades. For most modern automotive and consumer applications, cast iron falls into 4 separate categories: ... Doru M., et.al, "The Metallurgy and Tensile Mechanical Properties of Thin Wall Spheroidal Graphite Irons", International Journal ...
The possible inoculation mechanisms in spheroidal graphite cast irons have been thoroughly reviewed by Skaland5 following previous work which proposed a three-step model where a core of sulfide gets surrounded by a oxide shell on top of which a complex XO·MgO·SiO oxide precipitates (Figure 1a), where X may be Al, Ca or Ba.6 The …
Keywords: ductile cast iron, antimony, graphite nucleation, graphite growth, auger electron spectroscopy Introduction During solidification of mostly thick-walled ductile iron castings, the graphite has a tendency to degenerate during eutectic growth, which results in exploded or even chunky graphite. Possible reasons are long solidification ...
Ferritic high-Si ductile cast irons replace an unstable mixed ferrite-pearlite matrix with a unique combination of high elongation, strength and hardness (ideal for automotive drive train components) and resistance to oxidation and corrosion at high temperatures (automotive exhaust and turbocharger systems). The present paper …
In hypereutectic nodular cast irons, primary precipitation of graphite may lead to graphite flotation in thick section castings. …
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 …
Exploded graphite (x200). Courtesy of Zanardi Fonderie S.p.A. from publication: Degenerated graphite nodules influence on fatigue crack paths in a ferritic ductile cast iron | ferritic to a ...
Graphite cast iron materials, such as gray cast irons, austempered ductile irons, and ductile irons, are classes of structural material that are being produced at an ever-increasing rate. They are generally considered among prospective construction materials because of their promising tensile properties, yield strength, thermal stability ...
It has been reported that exploded graphite develops after the primary spheroidal nodules have reached some tens of microns in diameter. In this contribution, a model for this transition is presented.
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 …
graphite) and 35–70% for min. 0.80 (minimum Form VI graphite). The SSF is more representative than the RSF for Si-alloyed ductile cast iron, so it is recommended to use a graphite nodularity ...
The effects of certain elements on the formation of graphite in ductile iron have been investigated using directional solidification. This is shown that they are carbide formers in that they increase the undercooling for the formation of graphite [4]. ... may result in the formation of carbides and exploded or degenerate graphite. The residual ...
The structure of ductile iron castings usually includes not only spheroidal graphite particles, but also other objectionable deviations from the highest compactness (Table 1), resulting from many different causes 2, 3, 4.Superficial layers on ductile iron castings can include different variants of graphite morphologies, from a mixture of …
The precipitation of ultrafine graphite nodules improved strength and plasticity of ductile iron, which was mainly because ultrafine graphite nodules refined …
It also resists brittle fracture due to its graphite nodules. Production of ductile iron involves adding carbon and other elements like silicon, sulfur, manganese, and magnesium during the smelting process. Magnesium plays a crucial role in forming spherical graphite nodules and reducing sulfur content, which makes the iron and steel more brittle.
A Possible Mechanism for the Formation of Exploded Graphite in Nodular Cast Irons. Roxana Gerghu, Lena Magnusson Åberg, J. Lacaze. Published 1 May 2014. …
High alloyed Si ferritic ductile irons can offer potential benefits because they combine high strength, ductility at room temperature, and low oxidation rate at high temperature. ... The results revealed that exploded graphite appeared when the content of rare earth elements (Ce, La added with nodulizer) was above 0.02%. A Sb/Re ratio …
The three presented microstructural highlights on solid-state transformation of graphite, namely secondary graphite formation in ductile cast irons, graphite …
Addition of the appropriate amounts of the nodularizing compounds is of extreme importance, since excessive magnesium and cerium contents, for example, …