Metals play a huge part in manufacturing. Besides, many manufacturers employ metals like iron and steel because of their qualities, ranging from strength, durability, and the ability to retain sheen over an extended time.
However, while metals like cast iron and steel have a similar appearance, they are not the same. That is to say, they both have distinguishing features that could either be an advantage or disadvantage to a production process.
So, do you want to know the differences between cast iron vs steel? Is steel stronger than iron? Read on as we provide answers to these questions and the advantages and disadvantages of these two metals.
What’s Cast Iron?
This iron is made through smelting iron-carbon alloys. The carbon content of this alloy is often between 2-4%. To clarify, the cast iron has a carbon content higher than 2%. Furthermore, after the smelting process, the ironsmith pours the iron into a mold instead of working the iron with a hammer and tools.
Aside from carbon content, cast iron also contains 1-3% silicon, improving its casting performance. Besides, it contains trace amounts of manganese. Impurities like phosphorus and sulfur may also be present. The few common mechanical properties of cast iron include hardness, elasticity, ductility, and toughness.
There are different types of this brittle material, with the differences arising due to the different processing techniques and heat treatments employed during the process. The different types of cast iron include：
- Gray Iron
- White Iron
- Malleable Iron
- Ductile Iron
- Compacted graphite iron
What’s Steel?
Steel is an alloy of iron that contains a minute percentage of carbon, usually between 0.15 to 2%. The carbon content of steel makes it stronger while improving its resistance to breakage. It could also include other elements that will enhance its qualities, including silicon, manganese, phosphorus, Sulphur, and oxygen. For instance, stainless steel resistant to oxidation and corrosion often contains 11% chromium.
Steel has high tensile strength, which gives it application in producing tools, vehicles, machines, weapons, and even building infrastructure. It also has application in the use of steel guides for custom prototyping.
There are different types of steel. These include:
- Carbon Steel
- Alloy Steel
- Stainless Steel
- Tool Steel
Cast Iron Vs Steel: What Are Their Differences
What is the difference between cast iron and steel? The cast iron vs steel debate gets more complicated because they are quite different though both metals have a similar appearance. So let’s examine the other differences between them below.
| Cast Iron | Steel | |
| Carbon content | 2% to 4% | Less than 2% |
| Melting Point | 2200 degree Fahrenheit | 2500 – 2800 degrees Fahrenheit |
| Strength | More Compressive strength | More Tensile strength |
| Castability | Easy to cast because of low shrinkage and good flowability | Less easy to cast than cast iron as it has low flowability and more shrinkage. |
| Corrosion Resistance | Moderate to Low corrosion resistance | Higher corrosion resistance |
| Impact Resistance | Low impact resistance | High impact resistance |
| Cost | Cheaper because of the lower material cost, labor, and energy needed to produce the final product | More expensive than cast iron, although there are cheaper alternatives, like prefabricated steel forms like; rods, bars, beams, and tubes. |
| Applications | Pipe fittings, washers, farm equipment, machine parts, mining hardware, hand tools, and electrical fittings. | Infrastructure, vehicles, electrical appliances, rockets, tools, and weapons. |
Carbon Content
The main difference between cast iron and carbon steel is the carbon content. Cast iron contains over 2% carbon, while steel contains less than 2% carbon. However, steel can also contain other elements like chromium. The addition of these elements results in steel of different qualities and grades.
Melting Point
Cast iron has a lower melting point than steel. Its melting point is 2200 degree Fahrenheit, while that of steel ranges between 2500-2800 degree Fahrenheit. The low melting point of iron makes it easy to mold into any form or shape.
Strength
Cast iron and steel both deliver strong performance, but their strengths align with totally different application needs—cast iron dominates in compressive strength, while steel excels at tensile and impact strength. In practical industrial testing, cast iron has a compressive strength of 150-400 MPa, making it extremely resistant to pressure, dents and deformation—perfect for parts that bear heavy static loads. However, its tensile strength is only 100-200 MPa, so it’s brittle and easy to crack or break under sudden impact or bending force.Steel, by contrast, has a far higher tensile strength: regular carbon steel hits 400-600 MPa, and high-strength alloy steel can exceed 2000 MPa. This lets steel bend, stretch and resist sudden impacts without breaking, making it the top choice for load-bearing and structural parts.Simply put: if your project needs pressure resistance, cast iron is better; if it needs pull or impact resistance, steel is the stronger option.
Castability
Cast iron is easier to cast than steel. The reason is that it has more flowability and does not shrink. On the other hand, steel is less fluid, reacts to the mold material, and shrinks when it cools. To clarify, steel has a relatively high viscosity. The ease of casting iron makes it the perfect material for detailed ironwork structures.
Corrosion Resistance
While both look similar, cast iron resists corrosion and rust better than steel. However, these metal materials are not susceptible to corrosion. If you leave them exposed and unprotected, both materials will undergo oxidation, which would lead to decomposition.
Impact Resistance
Steel is better at resisting impact better than cast iron. This is especially true for sudden impacts. With sudden impacts, steel does not bend, break or deform as quickly as cast iron.
Cost
Cast iron is cheaper than steel because of the lower cost of material needed to produce cast iron. Furthermore, producing raw steel requires more labor and energy consumption.
Applications
Both materials have different applications. Cast iron is ideal for making pipe fittings, washers, farm equipment, machine parts, mining hardware, electrical fittings, and hand tools. On the other hand, steel is perfect for making tools, weapons, electrical appliances, vehicles, and infrastructure.
- Cast Iron: Cookware (skillets, Dutch ovens—even heat, needs seasoning); industrial use (enameled non-acidic food molds).
- Steel: Cookware (304 stainless steel—rust-resistant, easy to clean); industrial use (304/316 stainless steel for food processing/pharmaceutical equipment).
Cast Iron Vs Steel: Which One to Choose?
Choosing between these metals will require knowing the pros and cons of both metals. Below are their advantages and disadvantages.
Advantages and Disadvantages of Cast Iron
Advantages
- Good casting ability
- Available in large quantities, making production relatively inexpensive.
- It has a high compression strength
- Cast irons have good machinability
- Good anti-vibration property
- It has excellent wear resistance
- Low-stress concentration
- High resistance to deformation
- High durability
Disadvantages
- Prone to corrosion and rust
- Low tensile strength
- High impact resistance
- High weight-to-strength ratio
- High brittleness
Advantages and Disadvantages of Steel
Advantages of Steel
- Increased flexibility in design, as you can choose the alloy element you want to combine with steel
- Increased strength
- Resistant to corrosion
- Easy machining
Disadvantages of Steel
- More expensive than cast iron
- Less resistant to impact
So, between cast iron vs steel, Which do you prefer? Having seen the advantages and disadvantages of both types of materials, the one you ultimately choose to use would be dependent on your product requirements.
Cast Iron Vs Common Steel Types: Mild Steel & Carbon Steel
When comparing cast iron and steel, it’s important to distinguish between mild steel (low-carbon steel) and carbon steel—these two common steel types differ greatly from cast iron in performance and application, and are the most frequently compared materials in industrial manufacturing.
Cast Iron Vs Mild Steel (Carbon 0.05%-0.25%)
Mild steel has low carbon content, so it’s soft and easy to bend, weld and form. Its tensile strength is 300-400 MPa, not as high as carbon steel, but it’s far more tough than cast iron. It’s cheap to process and perfect for simple structural parts, frames and metal sheets. Cast iron, by contrast, has better compressive strength and vibration damping, and its casting cost is 20%-30% lower than mild steel’s machining cost—ideal for machine beds, pipe fittings and large batch formed parts.
Cast Iron Vs Carbon Steel (Carbon 0.25%-2%)
Carbon steel has higher carbon content, so its tensile strength jumps to 400-600 MPa, and it’s more wear-resistant than mild steel—great for tools, mechanical parts and high-load components. However, its casting fluidity is poor, so it can’t be made into complex shapes like cast iron. Cast iron’s biggest advantage here is its excellent castability: it can be poured into intricate molds in one step, while carbon steel needs multiple machining processes for complex parts, driving up costs.
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Conclusion
Cast iron and steel are two popular metal materials used in metal parts production. Between cast steel vs cast iron, we provide you with what you need to know above.
There are different types of cast iron; White Iron, malleable iron, gray Iron, compacted graphite iron, and ductile Iron. Steel also comes in different types; tool steel, stainless steel, alloy steel and carbon steel. These metal types have different uses and applications, and knowing the ideal one for your product is the first step in the right direction.
Do you want to source your metal parts? RapidDirect is just the best solution for you. With rapid online quotations and free DFM analysis, you start production faster.
FAQs
There is no straightforward answer to this question. Both materials have different types of strength. While cast iron has compressive strength, steel has more tensile strength. But generally, steel is more durable than cast iron.
Cast iron, like every other type, rusts on excessive exposure to moisture. This is especially true if there is no surface treatment on the cast iron.
One way to identify these metals is by using an abrasive wheel. Grind each metal specimen using the abrasive wheel and look for spark color and pattern. It is important to note that while steel gives off bright yellow sparks, irons produce orange or red sparks.
Depends—cast iron adds small iron for cooking, but needs seasoning; stainless steel is safer, non-reactive, ideal for food industry.
No—cast steel is better for high-load parts (higher tensile/impact strength); cast iron is better for low-cost, vibration-dampening, large-batch cast parts.
