Cast Iron vs Cast Steel

Understanding the differences between cast iron and cast steel is essential for selecting the right material for specific applications, especially in casting processes. Each material offers unique properties and advantages, making them suitable for particular uses. This article provides a detailed comparison of cast iron and cast steel.

Table Compare Cast Iron vs Cast Steel

Property Cast Iron Cast Steel
Composition Iron, 2-4% carbon, and 1-3% silicon Iron, 0.1-0.5% carbon, plus other alloying elements like chromium, nickel, manganese
Corrosion Resistance Moderate, better in some forms like ductile iron Generally better than cast iron, especially with alloy additions
Strength Good compressive strength, brittle Higher tensile strength, less brittle
Ductility Low High
Impact Resistance Lower, brittle material can shatter Higher, more resistant to impact
Cost Generally less expensive More expensive due to additional processing and alloying elements
Applications Pipes, machinery parts, automotive components like engine blocks Large industrial parts, automotive parts, mining equipment

What is Cast Iron?

Cast iron is a group of iron-carbon alloys with a carbon content greater than 2%. It is made by smelting iron ore and mixing it with scrap metals and other alloys. The liquid mixture is then poured into molds and allowed to solidify. Cast iron is prized for its durability, excellent heat retention, and resistance to deformation under load. It’s relatively brittle and has low tensile strength, making it unsuitable for bending and shock loads.

What is Cast Steel?

Cast steel, on the other hand, refers to a range of iron-carbon alloys with a lower carbon content than cast iron. It includes small amounts of other elements to improve its mechanical properties, such as strength and ductility. Cast steel is more ductile and impact-resistant than cast iron, making it suitable for components subject to dynamic loads.

How to Use Cast Iron


  1. Machinery Parts:
    • Ideal for gears, pulleys, and frames.
  2. Cookware:
    • Excellent for frying pans, woks, and baking dishes due to its heat retention properties.
  3. Automotive Components:
    • Commonly used for engine blocks and cylinder heads.

Working with Cast Iron

  1. Machining:
    • Can be machined easily due to its brittleness.
  2. Welding:
    • Difficult to weld; requires specialized techniques and pre-heating.

How to Use Cast Steel


  1. Mining Equipment:
    • Used for high-strength components like gears and pinions.
  2. General Engineering:
    • Suitable for structures requiring high strength and toughness.
  3. Automotive Parts:
    • Used in parts that require more durability and shock resistance.

Working with Cast Steel

  1. Machining:
    • More challenging to machine than cast iron but manageable with proper tools.
  2. Welding:
    • Easier to weld than cast iron and can be treated with standard welding techniques.

Differences Compare

Corrosion Resistance:

  • Cast Iron: Has moderate corrosion resistance. Some forms like ductile iron have better resistance due to their structure.
  • Cast Steel: Offers better corrosion resistance, which can be further enhanced by alloying elements.

Strength and Ductility:

  • Cast Iron: Known for its compressive strength but lacks ductility.
  • Cast Steel: Provides both high strength and ductility, making it more versatile under various load conditions.


  • Cast Iron: Less expensive due to simpler processing.
  • Cast Steel: More costly due to the materials and energy required in processing.


  • Cast Iron: Used where rigidity is more important than tensile strength.
  • Cast Steel: Preferred for applications requiring a balance of strength, toughness, and impact resistance.


The choice between cast iron and cast steel depends on your specific requirements, including the type of load, desired mechanical properties, cost considerations, and the application’s environmental conditions. Understanding these differences helps in selecting the most appropriate material for your needs.

FAQs about Cast Iron vs. Cast Steel

What is the main difference between cast iron and cast steel?

The main difference lies in their composition and mechanical properties. Cast iron has a higher carbon content, making it brittle and strong in compression but weak in tension. Cast steel has a lower carbon content and additional alloying elements, making it stronger and more ductile, suitable for dynamic loads.

Why choose cast iron over cast steel?

Choose cast iron if you need a material that provides excellent heat retention and resistance to deformation under load, such as for engine blocks, cookware, or machine parts. It is also generally cheaper than cast steel.

Why is cast steel preferred over cast iron for certain applications?

Cast steel is preferred when you need higher tensile strength, ductility, and impact resistance, such as in automotive parts, mining equipment, and other industrial applications that require durability against dynamic loads.

Can cast iron be welded?

Welding cast iron can be challenging due to its high carbon content, which makes it prone to cracking. Specialized welding techniques and pre-heating are often necessary to successfully weld cast iron.

How does the cost of cast iron compare to cast steel?

Cast iron is generally less expensive than cast steel. The lower cost is due to the simpler production process and less stringent material requirements compared to the high-quality alloys and processing needed for cast steel.

What are the corrosion resistance properties of cast iron vs. cast steel?

Cast iron has moderate corrosion resistance, which can be sufficient for many applications but not as robust as cast steel. Cast steel typically offers better corrosion resistance, especially when alloyed with elements like chromium and nickel.

What makes cast steel more ductile than cast iron?

The lower carbon content and the presence of alloying elements in cast steel improve its ductility, allowing it to withstand tensile stresses and dynamic loads better than cast iron, which is more brittle.

How are cast iron and cast steel machined?

Cast iron is easier to machine due to its brittleness, which allows for cleaner cuts without the material deforming. Cast steel, while tougher to machine, can still be effectively worked with appropriate cutting tools and conditions.

Which is heavier, cast iron or cast steel?

The density of both materials is similar; however, the specific weight can vary slightly depending on the type and amount of alloying elements used in cast steel. Generally, the difference in weight is not significant for most applications.

Are there different types of cast iron and cast steel?

Yes, there are several types of each. Cast iron includes gray iron, ductile iron, and malleable iron, each with unique properties and uses. Cast steel can vary widely in its alloy composition, affecting its strength, ductility, and resistance to wear and corrosion.

By understanding these differences, you can better decide which material is more suitable for your specific application, balancing factors such as mechanical properties, cost, and environmental suitability.