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 are used for different applications according to their 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 & ductile iron raw stock.
  1. Gray iron’s tensile strength ranges from 20,000 psi – 60,000 psi, whereas ductile iron’s 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

More Details about Versa-Bar Gray and Ductile Iron

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Difference between Gray and Ductile Cast 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 and Alloys 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 really comes from its low cost. Continuous cast gray iron combines affordable prices with quality lightweight metal to create a material that is ideal for applications such as vibration damping and use in manufacturing equipment frames. Gray iron is also applied in:

  • Construction equipment
  • Valves and fittings
  • Compressors and pumps
  • Diesel engine parts
  • Transportation system components

Gray iron is often mistakenly described as cheap and dirty metal, but its high cutting speeds, superior damping ability, durability and unique metallurgical makeup are making it more popular every day. Part of the gray iron’s success comes from its ability to be easily machined and as such is used where strength is not a critical requirement like manhole covers and counter weights.

Make no mistake, 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 Tubes

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 ductility makes it great for being shaped into wires and other applications that require a certain 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 often used in areas that necessitate the ability to elongate under tension. It is most often used in:

  • Couplings
  • Machine frames
  • Hydraulic valves
  • Pumps
  • Gear boxes

The many advantageous features of continuous cast ductile iron make it the perfect alternative to steel. American Iron and Alloys offers two types of 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. V-4 80-55-06 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 and Alloys means savings on every project.

American Iron & Alloys 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 exact 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 continuous cast iron suppliers at American Iron & Alloys for custom metal components and raw gray and ductile iron stock.
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