spheroidal graphite iron

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spheroidal graphite iron

metallurgy

Also known as: SG iron, ductile iron

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July 14, 2026

Quick Summary

Spheroidal graphite (SG) iron, also known as ductile iron, is a type of cast iron where graphite exists as small nodules rather than flakes. This is achieved by adding small amounts of elements like magnesium or cerium to molten iron, which transforms the graphite into spherical shapes.12

Cast iron itself is an alloy of iron containing 2-4% carbon, along with silicon and manganese. It is produced by reducing iron ore in a blast furnace and then casting the liquid iron into molds. While historically used in construction, steel has largely replaced it in that application. However, ductile irons are strong, malleable, and easy to cast, making them suitable for machine parts like gears and crankshafts.32

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aqueduct
Ductile iron, a stronger and more elastic type of cast iron, is one of the most common materials now used for smaller underground pipes (secondary feeders), which supply water to local communities.
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Ductile iron, a stronger and more elastic type of cast iron, is one of the most common materials now used for smaller underground pipes (secondary feeders), which supply water to local communities.
Read More

iron processing
White iron
…irons, which are also called ductile irons, are strong and malleable; they are also easy to cast and are sometimes preferred to steel castings and forgings.
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…irons, which are also called ductile irons, are strong and malleable; they are also easy to cast and are sometimes preferred to steel castings and forgings.
Read More

metallurgy
Grain size
…casting, the result is a “spheroidal graphite” iron, in which graphite appears as spherical nodules and ductility is greatly increased. If the molten iron is chill cast (i.e., rapidly cooled), it will form a “white” iron containing about 60 percent cementite, or iron carbide. This material is hard and wear-resistant,…
Read More
…casting, the result is a “spheroidal graphite” iron, in which graphite appears as spherical nodules and ductility is greatly increased. If the molten iron is chill cast (i.e., rapidly cooled), it will form a “white” iron containing about 60 percent cementite, or iron carbide. This material is hard and wear-resistant,…
Read More

water supply system
Materials
Ductile iron, a stronger and more elastic type of cast iron, is used in newer installations. Iron pipes are provided in diameters up to 122 cm (48 inches) and are usually coated to prevent corrosion. Underground sections are connected with bell-and-spigot joints, the spigot end…
Read More
Ductile iron, a stronger and more elastic type of cast iron, is used in newer installations. Iron pipes are provided in diameters up to 122 cm (48 inches) and are usually coated to prevent corrosion. Underground sections are connected with bell-and-spigot joints, the spigot end…
Read More