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Differences Between Carbon Steel vs Alloy Steel

Carbon Steel vs Alloy Steel

Steel is one of the most commonly used materials in the world. Steel is used for an unlimited amount of different applications. From giant steel beams in skyscrapers to small machine screws. Steel is available in a wide variety of unique alloys. Each steel alloy has a specific combination of elements that give it unique properties.  

Steel simply describes an iron-based metal alloy. Carbon steel and alloy steel describe two different groups of steel alloys. Understanding the key differences between carbon steel and alloy steel will help you decide which type of steel is best for your machined steel parts.

Key differences

The main difference between carbon steel and alloy steel is the alloying elements. Every type of steel is a mixture of mostly iron, and other metallic and nonmetallic elements. The alloying elements largely influence the durability, corrosion resistance, cost, and machinability of the steel.

Carbon steels are roughly 97% iron or more. Alloy steels contain slightly more alloying elements that improve the corrosion resistance and durability of the parts.

Quality Alloy Steel Carbon Steel
Corrosion resistance
Medium
Low
Machinability
Medium
Medium-High
Hardness
Medium
High
Strength
Medium-High
High
Toughness
Medium
High
Malleability
Low
High
Weldability
Low
Medium-High
Ductility
High
Low
Cost
Medium
Low

What is carbon steel?

Carbon steel is the most common type of steel used. As the name suggests, carbon steel is a mixture of carbon and iron. When carbon is added to any metal alloy, the alloy becomes stronger and the melting point increases. 

There are other elements in carbon steels, including lead, phosphorus, sulfur, and manganese. 

There are a range of carbon steels, from low-carbon alloys to high-carbon alloys. Low carbon steel alloys range from 0.05% to 0.3% carbon, while high carbon steel has 0.6% to 1.0% carbon content. That might not sound like much, but that small amount of carbon makes a big difference.

Low carbon alloys are more commonly used for machined steel parts, while high carbon alloys are used for things that require more strength, like high-tension springs and hand tools.

What is alloy steel?

Alloy steel describes steel alloys that have lower iron contents, and higher percentages of other elements. An alloy steel is mainly iron, but can contain up to 50% alloying elements.

The elements used in alloy steel largely depend on the purpose of the steel. On its own, iron isn’t usable for much. The common alloying elements like nickel, copper, chromium, and other elements are added to improve the durability, corrosion resistance, and appearance of the parts. 

Compared to carbon steels, alloy steels have much better corrosion resistance, but they also tend to be more expensive.

Common applications

Here are some common applications for both types of steel.

Alloy Steel Carbon Steel
Gears
Bolts
Valve components
Pins
Aircraft Parts
Shafts
Automotive Parts
Automotive Parts
Bolts
Gears
Pins
Rivets
Nuts
Spacers
Couplings
Rods
Crankshafts
Nuts

Spex is an ISO 9001:2015 certified company. Organizations use this standard to demonstrate the ability to consistently provide products and services that meet customer and regulatory requirements.

We incorporate world-class excellence in every step of the process, in our ongoing efforts to ensure your success.

Reach out to our team to get a quote for CNC machined steel parts for your next project. 

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