Similar to ductile iron, compacted graphite iron is produced by adding magnesium to a desulfurized base iron. As shown in Figure 3, CGI is stable over a range of approximately 0.008% magnesium (Mg), which is approximately five times smaller than the commercially used Mg-range for ductile iron.
How strong is compacted graphite iron?
While not quite as strong as ductile iron, CGI is 75 percent stronger and up to 75 percent stiffer than gray iron. The thermal and damping characteristics of CGI are midway between ductile and gray iron.
What is compacted graphite cast iron used for?
Compacted Graphite Iron has been increasingly accepted as automotive manufacturing material, showing its efficiency for several components, as brake discs and brake drums, exhaust manifolds, engine heads and diesel engine blocks, traditionally manufactured from gray cast iron (Guesser and Guedes, 1977).
What is the effect of having larger graphite flakes in cast iron?
The strength of gray cast iron depends on the matrix in which graphite (free carbon) is embedded. The matrix can range from ferrite to pearlite and various combinations of the two phases. Large graphite flakes reduce the strength and ductility, so inoculants are used to promote fine flakes.
What is another name for compacted graphite?
vermicular graphite iron
Compacted graphite iron (CGI), also known as vermicular graphite iron (GJV, VG, JV or GGV from the German: “Gusseisen mit Vermiculargraphit”) especially in non-English speaking countries, is a metal which is gaining popularity in applications that require either greater strength, or lower weight than cast iron.
How do you make cast iron malleable?
Malleable iron is cast as white iron, the structure being a metastable carbide in a pearlitic matrix. Through an annealing heat treatment, the brittle structure as first cast is transformed into the malleable form.
What is SGI material?
SG Iron is also known as Ductile Cast Iron, Nodular Cast Iron, Spheroidal Graphite Iron and Spherulitic Cast Iron. This grade of Iron was developed over 60 years ago and in the USA. The main characteristic of this material is the structure of the graphite.
How do you make austempered ductile iron?
Austempered ductile iron is produced by heat-treating cast ductile iron to which small amounts of nickel, molybdenum, or copper have been added to improve hardenability. Specific properties are determined by the careful choice of heat treating parameters.
What is the effect of phosphorus and sulphur in cast irons?
7. What is the effect of phosphorus and sulphur in cast irons? Explanation: Although sulphur stabilizes cementite, it causes brittleness. The same is true for phosphorus, due to which both elements are limited to a minimum quantity.
When sulphur is to be removed from cast iron while melting the same in cupola the flux used is?
Explanation: Limestone (CaCO3) is used as Flux in cupola furnace in a proportion of about 2-4% of the metal charge.
What is the difference between malleable and cast iron?
Gray cast iron has a high dampening capacity and is corrosion resistant. However it is brittle, and can be difficult to machine as it is hard to produce a smooth surface and can reduce tool life. Malleable iron has good shock resistance, is ductile and is very machinable.
Which material is used for manufacturing of malleable cast iron?
The white heart type has a different form of tempered carbon and usually contains some combined carbon, because of its composition and method of manufacture. “Cupola Malleable Iron” is a ferritic grade produced by cupola melting for pipe fitting and similar thin section castings.
What is compact compacted graphite iron?
Compacted Graphite Iron, which is also known as CGI or Vermicular Graphite Iron, is a form of cast iron in which the shape of the graphite particles is between that of conventional grey iron flakes and ductile iron where the graphite is in spheres.
How long have compacted graphite iron castings been in production?
Compacted Graphite Iron Production At Durham Foundry we have been producing compacted graphite iron castings for the last 30 years.
What are the applications of graphite iron in engines?
Applications. More recently compacted graphite iron has been used for diesel engine blocks. It has proven to be useful in the manufacture of V topology diesel engines where the loading on the block is very high between the cylinder banks, and for heavy goods vehicles which use diesel engines with high combustion pressures.
What is the advantage of graphite over ductile iron?
This graphite shape suppresses crack initiation and propagation and is the source of both the increased mechanical properties relative to grey iron and the improved thermal conductivity relative to ductile iron.
