The Difference between Ductile Iron and Gray Iron
Ductile and gray iron are the most commonly used metals in continuous casting due to their low material cost, high machinability, and high performance. Both metals are used for various applications, including construction equipment, pipe fittings, oil field machinery, and transportation services.
Due to differences in carbon levels, each metal has its advantages and is used for different applications based on its strengths.
| Gray Iron | Ductile Iron | |
|---|---|---|
| Tensile Strength | – | + |
| Thermal Conductivity | – | + |
| Ductility | – | + |
| Vibration Damping | + | – |
| Yield Strength | – | + |
| Machinability | + | + |
Contact continuous cast iron suppliers for raw gray and ductile iron stock. |
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- Gray iron’s tensile strength ranges from 20,000 psi to 60,000 psi, whereas ductile iron ranges from 65,000 psi to 80,000 psi and can be heat-treated to 100,000 psi
- Ductile iron has lower thermal conductivity, so it can insulate better than gray iron
- Ductile iron is more tailored for engineering applications
- Graphite in ductile iron is nodular and flaked in gray iron, meaning ductile iron is stronger and contains higher ductility
- Gray iron dampens vibration better than ductile iron
Details about gray and ductile iron
Gray Iron
AIA/Lawton Standard has the best replacement for steel: CC-2 Class 40, continuous-cast gray iron. During solidification, rod-like graphite flakes precipitate into the composition, outlining the difference between gray and ductile iron. Producers use grey continuous-cast iron for its high density and strength, but its popularity stems from its low cost. Continuous-cast gray iron combines affordable pricing with the quality and lightweight of a metal to create a material ideal for applications such as vibration damping and 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 a cheap and dirty metal. Still, its high cutting speeds, superior damping ability, durability, and unique metallurgical makeup make it popular. Part of gray iron’s success comes from its ease of machining and use where strength is not critical, such as 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 for immediate steel replacement. Ductile iron is the next step up.
Ductile iron
Ductile continuous cast iron has made its name in the machining industry due to its high tensile strength and flexibility. Its flexibility makes it ideal for shaping into wires and other applications requiring elasticity. Instead of rod-like flakes, the ductile iron bar is composed of graphite nodules, which makes it flexible during solidification. This type of iron is often used in areas that require elongation under tension. It is most often used in:
- Couplings
- Machine frames
- Hydraulic valves
- Pumps
- Gearboxes
The many advantages of continuous-cast ductile iron make it the perfect alternative to steel. AIA/Lawton Standard offers two high-quality ductile iron grades, CC-3 and CC-4. The distinctive metallurgical composition of CC-3 65-45-12 iron makes it the easiest to machine out of the three grades of continuously cast metal. CC-4 80-55-06 ductile iron is stronger than CC-3 and popular for automobile parts and hydraulic cylinders. Ductile iron is not only more versatile than steel but also costs significantly less.
We deliver raw stock and custom iron components
Ductile iron stock is available for sale as a raw material for you to process and finish independently. Alternatively, we can finish and machine it into custom continuous-cast iron components to your specifications 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 us for continuous cast iron supply, custom metal components, and raw gray and ductile iron stock.
