Steel is one of the most versatile and widely used materials within the construction, manufacturing, and engineering industries. Its strength, durability, and adaptability make it an indispensable part of modern manufacturing and production. With many different carbon and alloy SAE steel
grades available, it's crucial to understand different types of steel and the advantages they can provide your project.
Understanding SAE/AISI Steel Grades
The SAE/AISI steel grading system is a widely recognized method for classifying steel based on its chemical composition. Developed by the Society of Automotive Engineers (SAE) and the American Iron and Steel Institute (AISI), this system provides an intuitive framework for identifying steel types, enabling manufacturers and engineers to select the right material for various applications.
How Does the SAE/AISI Steel Grade System Work?
The SAE/AISI system uses a four-digit numeric code to identify steel composition. The first digit within the code indicates the steel's primary alloying element. The second digit provides information on what the subcategory or alloy group is. The last two digits indicate the approximate carbon content in hundredths of a percent. Check out the tables below for specific examples of how the SAE/AISI steel grading system operates.
First Digit – Steel Category
The first digit in the code indicates the steel's primary alloying element or category:
| First Digit Code |
Alloying Element |
| 1 |
Carbon Steel |
| 2 |
Nickel Steel |
| 3 |
Nickel-Chromium Steel |
| 4 |
Molybdenum Steel |
| 5 |
Chromium Steel |
| 6 |
Chromium-Vanadium Steel |
| 7 |
Tungsten Steel |
| 8 |
Nickel-Chromium-Molybdenum Steel |
| 9 |
Silicon-Manganese Steel |
Second Digit – Subcategory or Alloy Group
The second digit details the primary alloy group or the steel's modification. For example, in 10XX, the zero indicates plain carbon steel. In 41XX, the one indicates a chromium-molybdenum alloy steel.
Last Two Digits – Carbon Content
The last two digits specify the approximate carbon content in hundredths of a percent. For example, within code 1018, the carbon content would be roughly 0.18%, and within code 1045, the carbon content would be about 0.45%.
Popular SAE Steel Grades
Some of the most popular SAE steel grades include:
| Steel Type |
Description |
| 1008 |
Low-carbon steel provides excellent weldability |
| 1010 |
Low-carbon steel with excellent ductility |
| 1018 |
Low-carbon steel with high strength and hardness |
| 1020 |
Low-carbon steel provides excellent machinability, ductility, and weldability |
| 1025 |
Medium-carbon steel offers improved strength with good weldability and ductility |
| 1045 |
Medium-carbon steel with good strength and toughness |
| 4140 |
Chromium-molybdenum steel offers versatility, excellent strength, wear resistance, and toughness |
| 4130 |
Chromium-molybdenum steel offers excellent strength-to-weight ratio |
| 3160 |
Nickel-chromium steel offers a combination of toughness and wear resistance |
Carbon Steel
With a carbon range between 0.04% and 1.5%, carbon steel makes up about 90% of steel production. Carbon steel is often categorized by carbon content: mild, medium, or high carbon steel.
Mild Carbon Steel
Mild carbon steel contains 0.04% up to 0.30% carbon content. It is also known as "low carbon steel."
Mild Carbon Steel Properties
- Highly Machinable
- High ductility
- High weldability
- Cost-effective
Applications for Mild Carbon Steel
- Automotive components
- Structural steel
- Wiring
- Consumer appliances
- Machinery
- Forgings
- Tubing
Medium Carbon Steel
Medium carbon steel includes steel with carbon content ranging from 0.30% up to 0.60%.
Medium Carbon Steel Properties
- Medium strength
- Medium ductility
- Low hardenability
- Heat-treatable
Applications for Medium Carbon Steel
- Automotive components such as axles or gears
- Machine parts
High Carbon Steel
High carbon steel includes steel with carbon content ranging from 0.60% up to 1.50%.
High Carbon Steel Properties
- High hardness
- High strength
- Low machinability
- Low ductility
High Carbon Steel Applications
- Tooling
- Die casting
- Steel bars
- Railways
For rust protection and corrosion resistance, carbon steels are typically treated with hot-dipped galvanization.
Alloy Steel
Properties of
alloy steel must include other elements in the standard mixture of iron and carbon.
- Common elements are manganese, chromium, molybdenum, silicon, and nickel.
- These include greater hardness, corrosion resistance, heat resistance, and overall strength.
- Depending on the composition, some specialty alloy steels can be found in aerospace applications and aircraft components.
Tool Steel
Tool steels contain a more significant proportion of tungsten, molybdenum, chromium, and vanadium.
- With chemical properties like hardness and wear resistance, tooling steel can keep a sharp edge even in the hottest environments.
- It is ideal for crafting tools or applications that require cutting, extruding, and molding other metals.
- Tooling steel products include steel bar or steel plates and sheets.
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Purchase SAE Grades of Steel Today
Contact us for more information regarding our most popular SAE steel grades and
secondary service options. Our experts will assist you in finding the metal that's right for your specific application.
