Expertise in materials science is crucial for today’s foundries in order to choose the best cast iron metal for the end products at hand. Choosing the optimum iron type for your requirements and specifications is one major way Acme Foundry delivers the best, highest quality, and most cost-effective metal castings for each project.
Our foundry specializes in gray iron cast products – a material that offers outstanding thermal properties, damping characteristics, and excellent compressive strength combined with ease of workability and machinability. Furthermore, there’s a wide range of gray iron types and grades which allows us to further optimize the material properties of your end products. Below, we discuss these advantages in more detail compared to other types of common cast iron materials.
A Comparison of Cast Iron Metal Types: Advantages and Applications
Cast Gray Iron
Its high graphite content creates a nearly uniform gray appearance, hence the name. The graphite flakes microstructure gives gray iron its unique physical and mechanical properties. Learn more about the material properties and applications of gray cast iron in our earlier blog – What Is Gray Cast Iron?
- Excellent damping capacity (due to graphite flakes)
- Good thermal conductivity
- Low ductility (brittle)
- Easily machinable
Common product applications include:
- Engine blocks
- Manifolds
- Machine bases
- Pump housings
- Cookware
- Other consumer tools and appliances
Ductile Iron
Engineered for enhanced ductility, small amounts of magnesium or cerium modify the graphite structure into spherical nodules. The result is generally higher strength and a higher elongation rate, somewhat at the expense of gray iron’s exceptional thermal and damping properties.
- High tensile strength
- Excellent ductility and toughness
- Good wear resistance
- Vibration damping (less than gray iron)
- Machinable and weldable
Common product applications include:
- Pipes and fittings
- Automotive components (crankshafts, suspension parts)
- Machinery parts
- Pressure vessels
Cast White Iron
Contains a significant amount of cementite, or iron carbide. The cementite content forms a hard and brittle microstructure. Carbon remains combined throughout the iron rather than forming graphite.
- Extremely hard and wear-resistant
- Brittle (very low ductility)
- Poor machinability
Common product applications include:
- Wear-resistant surfaces such as liners for grinding mills
- Pump impellers
- Other high-wear or abrasion-prone components
Malleable Iron
A special type of white iron, malleable iron is produced by heat treating white iron, which converts carbon into irregular-shaped nodules of graphite. As the name suggests, the goal is to maximize malleability.
- Good ductility and toughness (less than ductile iron)
- Moderate tensile strength
- Excellent machinability
Malleable iron is typically best used for small and intricate cast iron components. Some common product applications include:
- Pipe fittings
- Brackets
- Hand tools
Chilled Cast Iron
Chilled cast iron is another type of specially processed white iron. Rapid cooling (chilling) during casting produces a hard surface layer with white iron characteristics, while the core retains gray iron properties. This results in a combination of hardness on the surface and toughness in the core with improved damping properties.
- Extremely hard surface (wear-resistant)
- Brittle outer layer
- Tough and shock-resistant core (due to gray iron)
- Poor machinability on the chilled surface, but the core is machinable
Common product applications include:
- Rolls for rolling mills
- Crushing equipment (like hammers and dies)
- Wear-resistant surfaces in industrial machinery
- Brake drums and engine block cylinders
120+ Years of Expertise in Gray Iron Casting
Founded in 1905, Acme Foundry has remained one of America’s leading specialists in gray iron casting and related foundry services. We apply decades of combined expertise in materials science to optimize each project for cost, quality, and speed of delivery.