Carbon Steel vs. Mild Steel

April 15, 2021 | Categorised in:



It’s a common question—What’s the difference between carbon steel and mild steel?

The answer is that mild steel is a type of carbon steel. All steel contains carbon, and when carbon is the primary alloying element in steel, that steel is considered carbon steel. However, the amount of carbon present in steel determines what type or grade of carbon steel it is. 

Mild steel has the lowest carbon content of carbon steel, but that doesn’t mean it’s less useful. In fact, mild steel is the most widespread form of steel and accounts for 85% of all steel production in the United States.

Read on to learn more about mild steel and how it compares to other forms of carbon steel.

What’s the difference between carbon steel and mild steel?

Mild steel is a type of carbon steel. The element carbon is present in all steel. Whenever this carbon is the main alloying element, the steel is considered carbon steel. Usually, carbon steel contains about 0.05-1.70% carbon by weight. The amount of carbon present determines whether it is mild, medium, or high carbon steel.

Is carbon steel harder than mild steel?

It is commonly asked whether carbon steel is harder than mild steel, but this is another trick question since mild steel is a type of carbon steel. There is a difference in hardness between the different types of carbon steel. Generally, the higher the carbon content in steel, the harder the steel is. However, this also means that the harder the steel, the more brittle it is. This means that high-carbon steel is harder than low-carbon steel but is also more brittle. This balance between hardness, ductility, and malleability makes mild carbon steel the ideal choice for most applications.

Mild vs. medium vs. high carbon steel

All steel containing carbon as the main alloying element is carbon steel, but the amount of carbon present dictates the type of steel and its properties. Here, we break down the differences between mild steel, medium carbon steel, and high carbon steel. 

Mild Steel

Mild steel, also known as “low-carbon steel,” is the most common form of steel for many reasons. It costs less while providing the material properties needed for most industrial applications. Mild steel contains approximately 0.05–0.25% carbon making it malleable and ductile. While mild steel has a lower tensile strength than other carbon steel types, it is more pliable and easier to form. You can also harden mild steel with various treatment processes. Mild steel is machinable and weldable, which aids in its usefulness for most applications.

Common uses of mild steel include:

  • Building construction
  • Pipelines
  • Automobile manufacturing
  • Wiring
  • And more

Medium-carbon steel

Medium-carbon steel has approximately 0.3–0.6% carbon content. Mild-carbon steel may be heat-treated by austenitizing, quenching, and then tempering to improve its mechanical properties. It’s most often utilized in a tempered condition, having microstructures of tempered martensite. Medium-carbon steel balances ductility and strength. This grade of steel is primarily used for applications that call for a combination of high strength and wear resistance, including:

  • machine components
  • gears
  • axles
  • forgings

High-carbon steel

High-carbon steel has approximately 0.60 to 1.00% carbon content. High-carbon steel almost always used in a tempered condition and, making it wear-resistant and capable of holding a sharp cutting edge. This makes it useful for applications such as knives, hammers, and other hand tools.

High-carbon steel’s hardness is higher than other steel grades, but that comes with a price when it comes to ductility. The higher the carbon content in steel, the less ductile it is. It is also typically much higher in price compared to mild steel. 

Service Steel Warehouse-Your carbon steel supplier

Service Steel Warehouse is the premier supplier of carbon steel products, including piling, beams, channels, pipe, sheets, and more. Not only do we have a wide inventory of products, but we also offer finishing services to process your order to your exact specifications, such as product sawing, galvanizing, and painting. If you’re unsure which service is right for your needs, talk to one of our steel professionals today.