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 ...
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 …
As part of a study devoted to the effect of trace elements on graphite degeneracy, near-eutectic ductile iron melts were prepared to which minute amounts of lead and of both lead and cerium were added. The melts were cast into an insulated Y4 mould, giving a solidification time of about 1 hour and a cooling time to room …
Graphite Morphology in Cast Irons - Volume 34. ... spheroidal, exploded, etc. is depicted in various microstructures. In addition, the relationship between certain compounds (e.g., titanium carbo-nitride, etc.) and graphite growth is demonstrated and discussed. ... Review ductile iron: fifty years of continuous development. Canadian ...
An analytical review of data on general-purpose grayed cast iron with different forms of graphite (lamellar, vermicular, globular, flaked) is presented. Grades of cast iron, their compositions, special features of structure of the graphite, and properties of gray, high-strength and malleable irons are described. The data on the kinds of iron …
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 ...
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 ...
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 ...
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 …
This article discusses the common grades of ductile iron that differ primarily by the matrix structure that contains the spherical graphite. The grades of ductile iron designated by their tensile properties in the specification ASTM A536 are presented in a table.
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 …
Ductile cast irons are materials having strength, impact toughness and ductility comparable to those of many grades of steel while exceeding by far those of standard gray irons. ... Exploded graphite is normally found in thicker section castings with slow cooling rates or at very high carbon equivalent levels. Figure 6: Sample with exploded ...
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 ...
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 …
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
exploded graphite in ductile iron. The Carbon Equivalent result determined by thermal analysis is different from the CE value derived from ... Figure 2: In hypereutectic irons, the heat released by primary austenite results in a thermal plateau at Point A. Thereafter, the onset of the eutectic solidification of graphite ...
Using literature data on iron melts, an expression of the surface tension of cast iron melts as a function of temperature and composition was obtained. Its predictions were satisfactorily compared with reported experimental results. Then, an analysis of experimental information of sessile drop experiments with cast iron melts onto graphite …
A Possible Mechanism for the Formation of Exploded Graphite in Nodular Cast Irons. Roxana Gerghu, Lena Magnusson Åberg, J. Lacaze. Published 1 May 2014. …
The three presented microstructural highlights on solid-state transformation of graphite, namely secondary graphite formation in ductile cast irons, graphite …
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 ...
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 …
Addition of the appropriate amounts of the nodularizing compounds is of extreme importance, since excessive magnesium and cerium contents, for example, …
In hypereutectic nodular cast irons, primary precipitation of graphite may lead to graphite flotation in thick section castings. …
The production of high quality ductile cast iron requires different and complex inoculants. Besides iron and silicon, they also contain alloying elements such as zirconium, strontium, barium, calcium and rare earth metals. The addition of these elements reduces carbide solidification and increases the number of eutectic cells, which improves the …
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 ...
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 ...
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 …
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 …
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 …
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 ...
Spheroidal graphite cast irons (SGCIs) have been widely used in automotive and energy industries requiring excellent mechanical strength and wear …
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 …
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.
The precipitation of ultrafine graphite nodules improved strength and plasticity of ductile iron, which was mainly because ultrafine graphite nodules refined …