Flotation of graphite influences expansion and contraction of the cast iron during eutectic solidification and thus also interferes with seal feeding. Irregular distribution of the graphite results in inconsistent properties …
Graphite flotation in ductile iron castings by T. N. Blackman, 1988, American Foundrymen's Society edition, in English
1. Introduction1.1. Chunky graphite. Spheroidal graphite cast iron (SGI), also known as ductile iron exhibits favorable ductility over other cast irons due to nodular graphite precipitations; however, in heavy section ductile iron castings or in whole SGI castings with higher alloying content, graphite degeneration can be observed, which is …
High silicon contents (between 3.2 and 4.2%) in the as-cast state are viewed as an opportunity to replace ferritic-pearlitic grades, avoiding potential hardness …
On the other hand, the appearance of some graphite degeneration such as chunky graphite has also been related to high silicon contents in ductile irons [4][5] [6] [7]. As for the mechanical ...
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 …
The degeneration and floatation of graphite are mainly attributed to prolonged local solidification time [5]. Nucleation of inoculated ductile iron begins during the liquid phase with main growth ...
irons with lamellar graphite), causing incomplete trans-formation into ausferrite and therefore inferior ductility in the range A 4 = 0.5–1.5%. The increasing carbon solubility in the austenite with increasing temperature (see line S–E in Fig. 1) can for ductile irons having graphite spheroids as carbon reservoirs
The article various reviews factors, such as microstructure, composition, and section effect, affecting the mechanical properties of ductile iron. It discusses the hardness properties, tensile properties, shear and torsional properties, damping capacity, compressive properties, fatigue properties, and fracture toughness of ductile iron.
Pan et al. [1] showed that. amounts of 0.01 wt.% Pb and higher lead to a graphite degeneration, namely type D or coral. graphite for high cooling rates and spiky graphite or irregular graphite in ...
The conventionally measured hardness of graphitic irons is influenced by the graphite, especially in gray iron. Martensite micro hardness may be as high as 66 HRC, but measures as low as 54 HRC conventionally in gray iron (58 HRC in ductile). The critical temperature of iron is influenced (raised) by silicon content, not by carbon content.
A study of the occurrence of graphite flotation as a function of carbon content in a ductile iron of base composition 2.50%Si, 0.16%Mn, 0.20%Mo, 0.50%Cu and the effect of its presence on the …
A ductile cast iron alloy was used in the experiments, containing 1.94 ± 0.02 wt.% Si for stabilisation of the graphite and 0.075 ± 0.005 wt.% Mg to enable the formation of graphite nodules. The overall composition is given in Table 1 .
The classification of grades inside a material family should be based on the properties required by design procedures. This paper proposes a reclassification of spheroidal graphite ferritic pearlitic and ausferritic (ADI) ductile cast irons grades based on yield strength (YS), strength ratio (SR) UTS/YS and elongation at fracture (EF). In …
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. ... Graphite floatation This is caused when large, low density graphite nodules are formed during the solidification of thick section or otherwise slow cooling castings ...
Ductile cast irons (DCIs) are of increasing importance in the renewable energy and transportation sectors. The distribution and morphology of the graphite …
Microstructure of gray and ductile irons consists with graphite particles and the iron matrix which can be considered as a composite structure. Therefore, variation of graphite morphology and fraction over the volume of a casting can be considered as an FGM. ... This is known as the graphite flotation commonly occurred in the …
Ductile iron is a special type of cast iron having properties comparable to steel. Also known as ductile cast iron, spheroidal graphite iron, spheroidal graphite cast iron, nodular cast iron, or SG iron, Ductile iron is an alloy of iron and carbon in graphite form. In the year 1943, ductile iron was first developed by Keith Millis in the ...
The three presented microstructural highlights on solid-state transformation of graphite, namely secondary graphite formation in ductile cast irons, graphite formation in high silicon medium carbon steels, and void formation during dissolution of graphite, …
Metallographic techniques for ductile irons are similar to those for other cast irons but more difficult than for steels, because graphite retention is a challenging task. This article presents recommended procedures to prepare ductile irons. It discusses three contemporary approaches for preparing ductile cast iron specimens with a wide range ...
However, for heavy section ductile iron castings, the mass fraction range of carbon equivalent should be reduced to 4.3-4.4%, otherwise, graphite floating will occur. If the heavy section ductile iron is cooled by metal mold, the carbon equivalent will be increased to 4.6-4.7%, and graphite will not float.
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...
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 …
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 …
This paper considers the most important quality factors in processing spheroidal graphite cast iron; namely, primary grains and graphite nodules in thin-walled ductile iron castings (TWDI). In the …
Typically, cast irons are made with uniform graphite morphology and distribution across the microstructure of castings. This research explored the possibility …
The present paper evaluates the graphite nodularity in 4.5%Si, commercial ductile cast iron (0.035%Mg res, 4.5%Si, 4.7%CE, Px = 2.3, K = 1.48), and un-inoculated conditions, solidified in thin wall …
Carbon flotation in ductile iron is caused when the foundry allows the Carbon Equilivant to exceed the ability of the magnesium to suppress graphite …
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 …
The equivalent carbon of the spheroidal graphite cast irons is convenient to be slightly hypereutectic—4.3–4.8% C—to improve the castability, and making possible the moulding of complex geometry parts. Carbon common percentages, between 3.5 and 3.8% C, emerge higher than in non-alloyed grey cast irons.
MeltLabGuy (Materials) 6 Jan 10 15:20. 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 magnesium 0.030 to 0.035%.
This paper considers the most important quality factors in processing spheroidal graphite cast iron; namely, primary grains and graphite nodules in thin-walled ductile iron castings (TWDI). In the present study, the effect of grain refinement (by means of Ti, Nb and Zr) and of the holding time after spheroidization and inoculation on …
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. ... Graphite floatation This is caused when large, low density graphite nodules are formed during the solidification of thick section or otherwise slow cooling castings ...
