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The Difference between Ductile Iron and Gray Iron

Continuous casting of ductile and gray iron dominates the industry in terms of low material cost, high machinability, and high performance. Both metals are used for a wide range of applications, including construction equipment, pipe fittings, oil field machinery, and even transportation services.

Each metal has its own advantage due to the differences in carbon levels and is used for different applications according to its strengths.

Gray Iron/Ductile Iron Comparison

  Gray Iron Ductile Iron
Tensile Strength +
Thermal Conductivity +
Ductility +
Vibration Damping +
Yield Strength +
Machinability + +
Contact continuous cast iron suppliers for gray and ductile iron raw stock.
  1. Gray iron’s tensile strength ranges from 20,000 psi – 60,000 psi, whereas ductile iron ranges from 65,000 psi – 80,000 psi and can be heat treated to 100,000 psi
  2. Ductile iron has lower thermal conductivity so it can insulate better than gray iron
  3. Ductile iron is more tailored for engineering applications
  4. Graphite in ductile iron is nodular and flaked in gray iron—meaning ductile iron is stronger and contains higher ductility
  5. Gray iron dampens vibration better than ductile iron

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More details about Versa-Bar gray and ductile iron

Gray and ductile iron, both superior alternatives to steel, each present a different makeup and suitability in the CNC machining industry.

Gray Iron

American Iron has the best replacement for steel in the form of V-2 Class 40 Versa-Bar continuous cast gray iron. During solidification, rod-like graphite flakes precipitate into the composition, outlining the difference between gray and ductile iron. Producers utilize grey continuous cast iron for its high density and strength, but its popularity comes from its low cost. Continuous cast gray iron combines affordable prices with quality lightweight metal to create a material ideal for applications such as vibration damping and use in manufacturing equipment frames. Gray iron is also applied in:

Gray iron is often mistakenly described as cheap and dirty metal. Still, its high cutting speeds, superior damping ability, durability, and unique metallurgical makeup make it popular. Part of the gray iron’s success comes from its ability to be easily machined and is used where strength is not a critical requirement, like maintenance hole covers and counterweights. Gray iron is considerably stronger than steel and costs less. You’ll save money in the short AND long run. Consider gray iron the immediate steel replacement. Ductile iron is the next step up.

Ductile iron

Ductile iron offers numerous machining advantages over gray iron.

Ductile continuous cast iron has made its name in the machining industry from its high tensile strength and flexibility. Its flexibility makes it great for being shaped into wires and other applications that require a level of elasticity. Instead of rod-like flakes, the ductile iron bar is composed of graphite nodules making it flexible during solidification. This type of iron is often used in areas that require the ability to elongate under tension. It is most often used in:

The many advantageous features of continuous cast ductile iron make it the perfect alternative to steel. American Iron offers two high-quality ductile iron grades, V-3 and V-4. The distinctive metallurgic composition of V-3 65-45-12 iron makes it the easiest to machine out of the three grades of continuously cast metal. ductile iron is stronger than V-3 and is a popular choice for automobile parts and hydraulic cylinders. Ductile iron is not only more versatile than steel but costs significantly less. Buying Versa-Bar continuous cast ductile iron from American Iron means savings on every project.

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American Iron delivers raw stock and custom iron components

Ductile iron stock is available for sale as a raw material for you to process and finish on your own, or we can finish and machine it into custom continuous cast iron components based on your requirements at our state-of-the-art CNC facility in Waukesha. It’s up to you. We provide you with high-quality ductile iron in whatever form you desire.

Contact American Iron for continuous cast iron supply, custom metal components, and raw gray and ductile iron stock.


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gray iron vs ductile iron