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NODULAR OR DUCTILE IRON (Grades 60-40-18, 65-45-12, 80-55-06)

In BM Foundry we take care of the casting of Nodular Iron or Ductile Iron, this type of iron has several interesting advantages.

The nodular or ductile iron is obtained by controlled introductionof molten magnesium into the iron, and low amounts of sulfur and phosphorus.
Obtained in this way a remarkable change in the microstructure of the metal, as the carbon is deposited in the ferritic matrix in the form of spheres unlike with what occurs in the gray iron in which the carbon takes the form of sheets.

The result of this change in structure, is a much stronger, durable and elastic iron. Compressive strength.

  • Abrasion resistance.
  • Ability to molding.
  • Fatigue.
  • Machinability.


Most of the carbon in nodular iron is shaped as spheroids. For producing the nodular structure the casting iron that is exiting the oven is inoculated with a small amount of materials such as magnesium, cerium, or both. This microstructure produces desirable properties such as high ductility, strength, good machining, good fluidity for casting, good hardenability and toughness. It can not be as hard as white cast iron, unless is subject to thermal, superficial, special treatment.

This type of casting is characterized in that the graphite appears as tiny spheres and thus the continuity of the matrix is discontinued much less than when it is in sheet form, this results in a tensile strength and toughness higher than ordinary cast iron. The nodular iron differs from malleable cast iron that is usually obtained as-cast directly without subsequent heat treatment. The total carbon content of ductile iron is equal to that of cast iron. The spheroidal graphite particles are formed during solidification due to the presence of small quantities of magnesium and cerium which are added to the ladle before casting the metal into molds, the amount of ferrite present in the matrix depends on the composition and of the cooling rate.
To continue listing advantages, we may mention a significant increase in tensile strength (420 N / mm2) and elevated with respect to the gray cast iron (180 to 200 N / mm 2); also the extensibility that is well above 5%.

This is why this type of casting, wich still retains the excellent properties of corrosion resistance of cast iron, behaves from a mechanical point of view, practically as steel. So, even having the same carbon content as the gray cast, ductile cast adds three important features:
  • Tensile and impact.
  • Significant elongation.
  • High yield.
It is a material that has similar characteristics to the Gray Iron but also has physical properties close to steel. It is also called a spheroid.
In this material we can quote the spares of the parts that require wear resistance and high stress.
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