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What You Need to Know about the Different Grades of Steel

If you’re in the market for steel, you may be wondering about the difference between steel grades used in a variety of applications and what benefits each grade offers. Here is a detailed look at the different types of steel and what they are used for:

1. Carbon Steel

Carbon steel is the most common type of steel that is the most widely used form of steel. It is made by adding (0.1% to 0.3%) carbon to iron. The amount of carbon added determines the strength and hardness of the steel. Carbon steel is relatively inexpensive and is used in a variety of applications, including:

  • Construction materials
  • Structural steel
  • Automotive parts
  • Pipe and tubing
  • Machine parts

2. Alloy Steel

Alloy steel is a type of steel that contains between 1% and 5% alloying elements, such as manganese, nickel, silicon, or copper, in addition to carbon. These additional materials improve the strength, hardness, or corrosion resistance of the steel. Alloy steel is used in a number of applications, including:

  • Automotive parts
  • Machine parts
  • Tools

3. Stainless Steel

Stainless steel is a type of steel that contains at least 10% chromium, which makes it resistant to corrosion. Stainless steel is used in a number of applications, including:

  • Food Processing
  • Kitchenware
  • Medical devices
  • Architecture

4. Tool Steel

Tool steel is made from a combination of iron, carbon, and other metals, such as chromium, vanadium, or molybdenum. It is the strongest and most durable type of steel, but is also the most expensive. Tool steel is often used for cutting and shaping metals. Tool steel is used in a variety of applications, including:

  • Cutting tools
  • Drilling tools
  • Molds

What Are the Different Grades of Steel

The steel grading system is a way of classifying different types of steel based on their composition and properties. The most common system in use today is the Unified Numbering System (UNS), which was developed by ATSM International (formerly as American Society for Testing and Materials) and the Society of Automotive Engineers (SAE).

UNS Grading System

The UNS grading system is an alloy designation system that uses a letter and a four-digit number to designate each alloy. The first letter is always ‘U’, and the second letter indicates the major alloying element. The four digits that follow indicate the composition of the alloy in weight percent. For example, the UNS designation for Type 304 stainless steel is ‘UNS S30400’.

SAE Grading System

The SAE grading system designates a four-digit number. The first two digits indicate the type of steel and alloy concentration, while the last two digits indicate the carbon concentration.

ASTM Grading System

The ASTM grading system is a standard system for the classification of steel. It designates each metal with a prefix depending on its category and a number describing its certain properties.

There are four grades of steel in the ASTM system:

  • Grade A is the lowest grade, with a minimum yield strength of 60 ksi (420 MPa).
  • Grade B is the next highest grade, with a minimum yield strength of 65 ksi (450 MPa).
  • Grade C is the next highest grade, with a minimum yield strength of 70 ksi (480 MPa).
  • Grade D is the highest grade, with a minimum yield strength of 80 ksi (550 MPa).

The grades of steel in the ASTM system are not necessarily equivalent to the grades used in other countries. For example, the grade designation “ASTM A36” in the United States is equivalent to the grade “JIS SS400” in Japan.

The ATSM system is a useful tool for both steel manufacturers and engineers. It allows manufacturers to produce steel to a specific strength and engineers to specify the strength of steel required for a particular application.


There are four main types of steel, namely, carbon, alloy, stainless, and tool. They are categorized using the steel grading system based on their unique properties and uses. Knowing the different grades of steel can help you choose the right material for your specific project needs.

KGS Steel Birmingham is the leading steel distributor in Birmingham, AL, specializing in all types of steel. We carry a wide range of steel products, including carbon, alloy, stainless, and tool steel. Our steel products are available in a variety of sizes and shapes, making it easy to find the perfect solution for your project. We also offer a variety of finishes so that you can choose the perfect look for your project. Let us help you choose the perfect steel solution for your needs. Contact us today to get started!

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