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Cast Iron vs Steel: Which One to Choose for Your CNC Project?

Metal is a basic part of industries such as manufacturing due to its strength, durability, and ability to retain sheen over an extended time. Among the several types of metal available in the market, cast iron vs steel is one of the many comparisons common among manufacturers who want to work with metal.

Selecting any of the two types of steel should only occur after understanding the properties of the project. Is cast iron stronger than steel? How is steel made from iron? This article breaks down everything you need to know about the difference between cast iron and steel. So, you can choose any of them for your project.


What’s cast iron?

Cast iron is produced through smelting iron-carbon alloys with a carbon content typically ranging between 2-4%. To clarify, cast iron contains a higher carbon content exceeding 2%. Instead of hammering and using tools, the molten iron is poured into a mold after the smelting process.

In addition to carbon, iron also contains 1-3% silicon, enhancing its casting performance. Traces of manganese may be present, and impurities like phosphorus and sulfur can also be found. Iron exhibits various mechanical properties such as hardness, elasticity, ductility, and toughness. This metal alloy is obtained by reducing iron ore in a blast furnace. Its composition includes varying proportions of silicon and manganese, along with small amounts of impurities such as sulfur and phosphorus.

Different types of this brittle material exist, resulting from various processing techniques and heat treatments employed during production. The various types of cast iron comprise:

  • Gray Iron

  • White Iron

  • Malleable Iron

  • Ductile Iron

  • Compacted Graphite Iron

What’s steel?

Is steel made of iron? Steel is an alloy of iron and carbon in which the carbon content ranges up to 2 percent (with a higher carbon content, the material is defined as cast iron). The presence of carbon in steel contributes to its increased strength and resistance to breakage. Additionally, steel can be alloyed with other elements such as silicon, manganese, phosphorus, sulfur, and oxygen to enhance its properties. For example, stainless steel, which is resistant to oxidation and corrosion, often contains 11% chromium.


With its high tensile strength, steel has numerous applications in manufacturing tools, vehicles, machinery, weapons, and infrastructure construction. It is also utilized in the fabrication of steel guides for customized prototyping purposes.

The various types of iron comprise:

What is the difference between steel and cast iron?

Are cast iron and iron steel the same? They only have a similar appearance. In contrast, there are many cast iron and steel differences. You may ask the questions. Is steel stronger than cast iron? Or is cast iron stronger than steel? Let’s examine the difference between them and give you have clear idea of which is stronger: cast iron or steel.


Cast Iron



High carbon content, with 2-4% carbon

Steel made from iron (called iron steel), and with other elements


Brittle and exhibiting low tensile strength

Resilient and possessing high tensile strength


Hard and brittle

Varies based on the specific type


Less Malleable

Malleable, capable of being molded and shaped.


Less ductile

Ductile, and capable of being Stretched Without Fracturing


More cost-effective to produce due to its lower material cost, reduced labor requirements, and lower energy consumption during the production process

More expensive than cast iron, despite the presence of cheaper alternatives such as prefabricated steel forms like rods, bars, beams, and tubes


Construction, automotive manufacturing, machinery and equipment, appliances, tools, and infrastructure development

Aerospace, shipbuilding, energy production, machinery and equipment manufacturing, weapons and defense, electrical appliances

  • Strength

For strength, which is stronger, cast iron or steel? Cast iron generally possesses more strength compared to steel. Conversely, steel exhibits greater tensile strength, allowing it to bend without breaking. To clarify, the high compressive strength of iron makes it highly resistant to dents and bending, but it is prone to breaking under excessive pressure.


  • Castability

Iron is easier to cast than steel due to its higher flowability and minimal shrinkage. In contrast, steel has a lower fluidity, reacts with the mold material, and contracts as it cools. Steel also has a relatively high viscosity. The superior castability of iron makes it suitable for intricate ironwork structures.

  • Corrosion Resistance

Is steel and cast iron the same in corrosion resistance? Cast iron possesses better resistance to corrosion and rust compared to steel. However, it's important to note that neither material is completely immune to corrosion. If exposed and unprotected, both cast iron and steel will undergo oxidation, leading to decomposition.

  • Impact Resistance

Is iron or steel stronger? Steel exhibits superior impact resistance compared to iron, especially when it comes to sudden impacts. Steel is less prone to bending, breaking, or deforming quickly under these circumstances.

  • Cost

Is cast iron the same as steel? Cast iron is generally less expensive than steel due to the lower cost of materials required for its production. Additionally, the production of raw steel involves more labor and energy consumption.

  • Applications

Both materials find applications in different fields. Cast iron is commonly used in the manufacturing of pipe fittings, washers, farm equipment, machine parts, mining hardware, electrical fittings, and hand tools. Conversely, steel is well-suited for the production of tools, weapons, electrical appliances, vehicles, and infrastructure.


Cast Iron vs Steel: Pros and Cons

Before you choose the right material, you should know their respective advantages and disadvantages.

Pros of Cast Iron

  • High compressive strength: Cast iron exhibits excellent strength when subjected to compressive forces.

  • Castability: Cast iron has lower melting and casting temperatures, better flowability, and reduced shrinkage compared to steel. This makes it cheaper and easier to cast.

  • Machinability: Softer types of iron, like gray iron, are easy to machine quickly and accurately.

  • Hardness: Cast iron possesses high hardness compared to other low-cost metals.

  • Cost efficiency: Cast iron offers a variety of advantageous properties at a relatively low cost.

Cons of Cast Iron

  • Susceptibility to corrosion: Cast iron is prone to rust and corrosion when exposed to moisture and oxygen.

  • Brittle behavior: This iron can be prone to brittleness, making it less suitable for applications requiring high impact resistance.

  • Lower tensile strength: Cast iron typically has lower tensile strength compared to materials like steel.

  • Limited malleability: Cast iron is not as malleable as some other metals, which can limit its ability to be shaped and formed.

Pros of Steel

  • High tensile strength: Steel, depending on the alloy used, can possess significantly higher tensile strength compared to iron.

  • Toughness and ductility: Steel can deform under high stress without breaking, making it more resistant to cracking and offering better impact performance.

  • Weldability: Steel generally offers good weldability, making it easier to join and fabricate using welding techniques compared to cast iron, which is challenging to weld without causing cracks.

Cons of Steel

  • Higher cost: Steel is generally more expensive than other materials, such as cast iron.

  • Susceptibility to corrosion: Steel is prone to rust and corrosion, especially when exposed to moisture and certain environments.

Richconn, Best Sheet Metal Service Provider

Deciding between cast iron and steel can be challenging. It boils down to the nature of your project and the investment you’re ready to make. At Richconn, we simplify this choice for you.

  • Versatility for Any Project: Regardless of the simplicity or complexity of your parts, and whether you need them in small or large quantities, our expertise can accommodate all your requirements.

  • Efficient Ordering: Enjoy a quick and simplified ordering process with instant quotes and the added benefit of our complimentary analysis when you upload your design files.

  • Expert Recommendations: Our knowledgeable engineers will carefully review your designs and provide expert recommendations on the most efficient sheet metal process. This personalized approach helps you save time and minimize costs.



Cast iron and steel are both valuable construction materials, each possessing distinct characteristics. This type of iron stands out for its exceptional compression strength and heat resistance, while steel offers superior tensile strength, machinability, and corrosion resistance. The choice between cast iron and steel depends on factors such as the specific requirements of the application, budget, and desired properties. By comprehending the similarities and differences between these materials, engineers and manufacturers can make educated decisions and choose the most suitable material for their projects.

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