Difference Between Ductile Iron and Cast Iron

2023.2.28

Today, let’s take a look at the comparison between ductile iron and cast iron.

 

 

What are Ductile Iron and Cast Iron

Cast iron is a type of iron alloy that is made by melting iron and adding carbon, silicon, and other elements to form a molten mixture. The mixture is then poured into molds to create the desired shape. Cast iron is known for its excellent casting properties, and it is often used in the production of pipes, cookware, and machine parts.

 

Ductile iron, also known as nodular cast iron or spheroidal graphite iron, is a type of cast iron that has improved ductility and toughness due to the addition of small amounts of magnesium or other rare earth metals. Ductile iron has a microstructure of graphite nodules or spheres, which gives it better mechanical properties than traditional cast iron. Ductile iron is often used in the production of automotive components, gears, and construction materials.

 

Ductile iron has higher tensile strength, yield strength, and elongation than cast iron, making it more resistant to impact and fatigue. Ductile iron is also more ductile and has better machinability than cast iron. However, cast iron is typically more cost-effective and has better thermal conductivity than ductile iron.

Difference Between Ductile Iron and Cast Iron

Ductile iron vs cast iron corrosion

Both ductile iron and cast iron are prone to corrosion, but their corrosion resistance can be improved through various methods.

– Cast iron is relatively resistant to atmospheric corrosion but is susceptible to internal corrosion caused by moisture, chemicals, and oxygen. Corrosion inhibitors, coatings, and cathodic protection can be used to improve the corrosion resistance of cast iron.

– Ductile iron, on the other hand, has better corrosion resistance than cast iron due to its higher nickel and chromium content. Ductile iron is less susceptible to atmospheric and internal corrosion than cast iron, but it can still be affected by aggressive environments. Corrosion inhibitors, coatings, and cathodic protection can also be used to protect ductile iron from corrosion.

 

Ductile iron vs cast iron weight

– Cast iron is a dense and heavy material, with a typical density of around 6.9 to 7.8 grams per cubic centimeter (g/cm³). The exact density can vary depending on the specific composition and manufacturing process used. Cast iron is known for its high weight and is often used in applications where weight is not a significant concern, such as in machine parts, pipes, and cookware.

– Ductile iron is also a dense material, with a typical density of around 6.9 to 7.3 g/cm³. While ductile iron is slightly less dense than cast iron, the difference is relatively small and may not be significant in most applications. However, ductile iron is known for its higher strength and toughness compared to cast iron, making it a popular choice in applications where weight and durability are important, such as in automotive components and construction materials.

 

Ductile iron vs cast iron cost

– In general, cast iron is often less expensive than ductile iron because it is simpler to produce and requires fewer additives. Cast iron is commonly used in applications where cost is a significant concern, such as in pipes, machine parts, and cookware.

– Ductile iron is typically more expensive than cast iron due to its improved mechanical properties, including higher strength, toughness, and ductility. The addition of magnesium or other rare earth metals to the iron alloy also adds to the cost of production. Ductile iron is commonly used in applications where strength and durability are important, such as in automotive components and construction materials.