Ductile Iron vs Cast Iron: Difference and Comparison

Casting is the term used to describe the manufacturing of an element by pouring a liquid substance into the mold, which results in the formation of a solid substance when kept for some time.

Key Takeaways

1. Ductile iron is an iron alloy containing graphite nodules, which give it superior strength and ductility; cast iron is a group of iron-carbon alloys with a carbon content of over 2%, known for its brittleness.
2. Due to its high ductility, ductile iron is more resistant to impact and fatigue, making it suitable for demanding applications like automotive components and machinery parts; cast iron’s brittleness restricts its usage to less dynamic applications, such as pipes, stoves, and decorative elements.
3. Cast iron exhibits excellent heat retention and even heat distribution, making it a popular choice for cookware; ductile iron’s mechanical properties overshadow its thermal characteristics, making it less commonly used in cookware production.

Ductile Iron vs Cast Iron

Ductile iron, called spheroidal iron, is a type of graphite-rich iron that contains spherical graphite nodules. It has a yield strength of 40k. Cast iron is a family of iron–carbon alloys that have small flakes of graphite with no yield strength and half the tensile strength of ductile iron.

Ductile iron, otherwise known as spheroidal graphite iron, has become one of the most popular iron alloys these days. It has some interesting properties and capabilities that set its bar high.

On the other hand, Cast iron is such an iron alloy that it has been there for a long time now. It comes in various types as well. It is harder and brittle.

Comparison Table

Parameters of Comparison	Ductile Iron	Cast Iron
Origin	Ductile iron got discovered in 1943.	Cast iron got discovered during the 5th Century BC.
Texture	It is relatively softer in texture.	It is harder.
Composition	Along with Carbon as the primary element, it contains Silicon, Manganese, Magnesium etc.	It contains Carbon and Silicon as the primary composition.
Brittle	It is less brittle.	It is more brittle in comparison.
Elongation	It can result in around 18 per cent elongation.	It only has around 0.5 per cent elongation.
Tensile Strength	It has more tensile strength.	The tensile strength of Cast iron is less.
Machinability	It has decent machinability.	It has a good one.
Weldability	Its weldability ranges from low to medium depending on the procedure.	It has medium weldability.
Pricing	It has priced at higher rates.	It has a lower price in comparison.

What is Ductile Iron?

Ductile Iron is a type of Cast Iron that is rich in graphite. It was first discovered by Keith Millis in 1943. But its production didn’t start until 1949.

Ductile iron is one of the most commonly produced iron varieties in the world today. It is composed of Carbon, Silicon, and Manganese as primary contents.

The term ‘Ductile’ means a substance that can be easily molded into a thin wire. In addition to this, it is less brittle and is capable of tolerating impacts, and does not fracture easily.

The primary application of Ductile iron is for automotive components. Others include diesel trucks, agricultural tractors, oil well pumps, etc.

What is Cast Iron?

Cast Iron started to be used for making artifacts in the 5th Century BC. It is a type of iron that has been there for years and has expanded into several varieties over time.

Carbon covers the highest percentage of Cast iron’s composition. Silicon is used for stabilizing the graphite molecules in order to maintain the properties of cast iron.

There are several varieties of Cast iron, including Malleable Cast iron, White Cast iron, and Grey Cast iron. Cast iron is brittle, but malleable cast iron remains an exception.

Cast iron is very popularly used as an engineering substance. Therefore, it is used for various things like pipes, and the automotive industry, i.e., cylinder blocks, heads, etc.

Main Differences Between Ductile Iron and Cast Iron

1. Ductile iron has more tensile strength than Cast iron.
2. Ductile Iron is costlier than Cast Iron.

References

1. https://link.springer.com/article/10.1007/s00170-016-8510-y
2. https://www.jstage.jst.go.jp/article/isijinternational1989/41/4/41_4_372/_article/-char/ja/