The Difference between Ductile Iron and Gray Iron

Understanding the Distinctions between Ductile Iron and Gray Iron

In the industry, continuous casting of both ductile and gray iron prevails due to their cost-effectiveness, excellent machinability, and robust performance. These materials find extensive use in various sectors, including construction machinery, pipe fittings, oil field equipment, and transport services.

For more information on ductile iron vs gray iron, contact us. Our expert sales team will assist you in choosing the optimal material for your specific needs.

The varying carbon content in each metal provides distinct advantages, making them suitable for different applications based on their respective strengths.

Comparative Analysis of Gray Iron and Ductile Iron

Gray Iron vs Ductile Iron

• Tensile Strength: Ductile Iron +, Gray Iron –
• Thermal Conductivity: Ductile Iron +, Gray Iron –
• Ductility: Ductile Iron +, Gray Iron –
• Vibration Damping: Gray Iron +, Ductile Iron –
• Yield Strength: Ductile Iron +, Gray Iron –
• Machinability: Both +

Reach out to continuous cast iron suppliers for gray and ductile iron raw stock.

1. 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 up to 100,000 psi.
2. Ductile iron has lower thermal conductivity, making it a better insulator compared to gray iron.
3. Ductile iron is specially designed for engineering applications.
4. In ductile iron, graphite is nodular, whereas it is flaked in gray iron—resulting in higher strength and ductility for ductile iron.
5. Gray iron excels in vibration damping over ductile iron.

Details about Versa-Bar Gray and Ductile Iron

Both gray and ductile iron serve as outstanding alternatives to steel, each with unique compositions and advantages in the CNC machining industry.

Gray Iron

American Iron offers V-2 Class 40 Versa-Bar continuous cast gray iron as a superior substitute for steel. The presence of rod-like graphite flakes during solidification defines the difference between gray iron and ductile iron. Gray iron is valued for its high density and cost-effectiveness, making it ideal for applications that require vibration damping and lightweight material. It is commonly used in:

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

Gray iron, despite being labeled as economical and inferior, boasts high cutting speeds, superior damping properties, and a unique metallurgical configuration. It is preferred for applications where extreme strength isn't required, such as maintenance hole covers and counterweights. Additionally, gray iron is significantly stronger than steel and less expensive, offering savings in both short and long-term projects. Consider gray iron an immediate replacement for steel, while ductile iron serves as the next step up.

Ductile Iron

Ductile iron presents numerous advantages in machining over gray iron.

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Ductile continuous cast iron is renowned for its high tensile strength and flexibility, essential for applications requiring elasticity. Unlike rod-like flakes, graphite in ductile iron forms nodules, enhancing flexibility. This type of iron is widely used in sectors where materials need to stretch under stress, commonly found in:

• Couplings
• Machine frames
• Hydraulic valves
• Pumps
• Gearboxes

The advantageous properties of continuous cast ductile iron make it a preferred alternative to steel. American Iron's premium grades, V-3 and V-4, further enhance its machinability and strength. V-3's 65-45-12 iron composition provides ease of machining, whereas V-4 80-55-06 ductile iron delivers superior strength, ideal for automotive parts and hydraulic cylinders. Ductile iron not only offers greater versatility than steel but also proves significantly more economical. Purchasing Versa-Bar continuous cast ductile iron from American Iron guarantees cost savings on every project.

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American Iron Offers Raw Stock and Custom Components

Available for sale as raw material, our ductile iron stock can be processed and finished by you, or we can customize and machine it into specific continuous cast iron components at our advanced CNC facility in Waukesha. We provide high-quality ductile iron in the form you need.

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

Differences Among Gray, Malleable, and Ductile Iron in Machining

In machining castings, gray iron offers ease, while ductile iron can be challenging. At Moline Iron Foundry, test bars were turned from every melt to measure tensile strength. While gray bars posed no issue, ductile bars with hard spots could quickly damage carbide inserts and disrupt operations. Similarly, in milling, hitting a hard spot in a ductile iron casting wore out carbide end mills rapidly. Gray iron filled cavities well and provided better detail compared to ductile, with notable sulfur smell in hot casts. Venting and gating for ductile casts required trial and error due to gas hole issues.

The primary distinction among gray, malleable, and ductile iron lies in their graphite structure. Gray iron features graphite flakes within a pearlite-ferrite matrix, offering machinability and vibration damping but limiting mechanical properties. Malleable iron contains nodular graphite in a ferritic matrix with less impact on mechanical properties. Ductile iron's graphite, in spheroid forms, produces tensile strengths over 150,000 psi through the addition of magnesium alloy during casting.

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