What is carbon steel (C-Steel)?

CEO of ABRAMS Industries Steel Supploer

Written by Dr. Juergen Abrams on July 3, 2024.

Carbon steel (Plain carbon steel) is an iron-carbon alloy with a carbon content range from 0.05% to 2.1% by weight. It contains a maximum of manganese (1.65 wt.%), silicon (0.6 wt.%) and copper (0.6 wt.%). It does not contain significant amounts of other alloying elements, distinguishing it from alloy steels.


C-steel can be divided into Low, Medium, High and Ultra High based on its carbon content. It is known for its high hardness, strength, and resistance to wear.

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CLASSIFICATIONS OF CARBON STEEL:

Carbon steel is classified based on its carbon content and other alloying elements, as described in the AISI definition. Each classification serves different industrial needs and applications based on its mechanical properties and characteristics. The primary classifications are as follows:

Low Carbon Steel:


Carbon content: 0.05% to 0.25%.


Characteristics: Soft, ductile, and easily weldable.


Uses: Structural shapes, auto body panels, wire products, etc.

Medium Carbon Steel:


Carbon content: 0.25% to 0.6%.


Characteristics: Higher strength and hardness than low carbon steel but less ductile.


Uses: Gears, axles, railway tracks, etc.

High Carbon Steel:


Carbon content: 0.6% to 1.4%.


Characteristics: Very hard and strong, less ductile, and difficult to weld.


Uses: Cutting tools, springs, high-strength wires, etc.

Ultra-High Carbon Steel (UHCS):


Carbon content: 1.25% to 2.1%.


Characteristics: Extremely hard and brittle.


Uses: Specialized applications like knives, axles, and certain machinery parts (non-industrial-purpose).

COMMON GRADES OF CARBON STEEL:

The properties of carbon steels are primarily influenced by the carbon content and the presence of trace amounts of other elements. Common grades of carbon steel are e.g. 1045, 1018, A36 or W1.

Chemical Composition
1045 Steel

Carbon (C): 0.42-0.5%


Silicon (Si): 0.15-0.4%


Manganese (Mn): 0.60-0.80%


Phosphorus (P): ≤ 0.03%


Sulfur (S): ≤ 0.03%
1018 Steel

Carbon (C): 0.15 - 0.2%


Silicon (Si):  ≤ 0.4%


Manganese (Mn): 0.60-1.2%


Phosphorus (P): ≤ 0.04%


Sulfur (S): ≤ 0.05%
A36 Steel:

Carbon (C): 0.25 - 0.29%


Silicon (Si):  ≤ 0.4%


Manganese (Mn): 0.6-1.2%


Phosphorus (P): ≤ 0.04%


Sulfur (S): ≤ 0.05%

W1 Steel

Carbon (C): 0.9-1.05%


Silicon (Si): 0.1-0.25%


Manganese (Mn): 0.3-0.4%


Phosphorus (P): ≤ 0.025%


Sulfur (S): ≤ 0.025%


Chromium (Cr): ≤ 0.2%


Molybdenum (Mo): ≤ 0.1%


Vanadium (V): ≤ 0.1%


Tungsten (W): ≤ 0.2%

1045 Carbon Steel (C45U)

AISI 1045 carbon steel (C45U) is a medium carbon steel that is widely used in industrial and engineering applications due to its balance of strength, toughness, and wear resistance. 

A36 Carbon Steel

AISI A36 carbon steel is one of the most commonly used grades of structural steel. It is a low carbon steel with excellent mechanical properties and good weldability, making it suitable for a wide range of applications.

1018 Carbon Steel

AISI 1018 carbon steel (C18) is a low carbon steel that is widely used in various applications due to its good balance of strength, ductility, and ease of machining and welding.

W1 Carbon Steel (C90U)

AISI W1 carbon steel, also known as C90U steel, is a high carbon steel with excellent hardness and wear resistance, making it suitable for applications requiring high strength and durability. It is suitable for a wide range of applications requiring durable and high-performance materials. 

CARBON STEEL CHART

This table provides a quick overview of the differences and similarities between the various types of carbon steel.
• Welding
• Hardness
• Surface Hardness
• Tensile Strength
• Yield Strength
carbon-steel-chart

WHAT IS CARBON STEEL USED FOR?

Carbon steel is used in a wide variety of applications across multiple industries due to its versatile properties. Here are some of the primary uses of carbon steel:

Manufacturing and Fabrication

Consumer Goods

Construction Tools

Defense and Military

Construction and Infrastructure

Industrial Equipment

Manufacturing and Fabrication

Energy Sector

Railways

Agriculture

Shipbuilding

CARBON STEEL FAQ

Is carbon steel stronger than other steel?

Does carbon steel rust easily?

Can carbon steel be welded?

Carbon Steel vs. Mild Steel


Mild steel
, also known as low carbon steel, is a type of carbon steel that contains a relatively low percentage of carbon, typically around 0.05% to 0.25% by weight. This low carbon content gives mild steel several notable characteristics.

Carbon steel vs. low alloy steel


When comparing carbon steel to
low alloy steel, there are several key differences in terms of composition, properties, and applications.

AISI Definition of carbon steel


The
American Iron and Steel Institute (AISI) defines carbon steel as follows:

Carbon steel is defined as steel that meets the following criteria:

Manganese Content: The maximum content of manganese does not exceed 1.65%.


Silicon Content: The maximum content of silicon does not exceed 0.60%.


Copper Content: The maximum content of copper does not exceed 0.60%.


Other Elements: No minimum content is specified for other alloying elements such as chromium, cobalt, molybdenum, nickel, niobium, titanium, tungsten, vanadium, zirconium, or any other element to be added to obtain a desired alloying effect.


What are the disadvantages of carbon steel?

Carbon steel, while widely used and valued for its versatility, has several disadvantages

  • Carbon steel is prone to rust and corrosion.
  • High and Ultra-High carbon steel can be quite brittle.
  • Higher carbon content in steel can make welding more difficult.
  • Lower ductility and malleability compared to some other steel alloys.
  • Improper heat treatment can lead to undesirable properties.
  • Carbon steel with a higher carbon content can be more difficult to machine.
  • Carbon steel tends to tarnish and discolor.

In summary, carbon steel has many advantageous properties, including strength, affordability, and availability. Its drawbacks regarding corrosion resistance, brittleness, and other factors should be taken into account when selecting steels for specific applications.

CUSTOMIZED CARBON STEEL

As a steel supplier with no minimum order quantity or value we have been supplying steel to a wide variety of industries and manufacturers in Germany since 2003, Europe since 2011 and now since 2020 across the U.S.A. and Canada.

We pride ourselves in supplying you with precision in tool steel, high speed steel, stainless steel, heat-treatable steel and case hardening steel in 44 steel grades with more than 53,000 dimensions.