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19 March 2026 at 16:54 • 5 mins read
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.
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.
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.
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 |
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.
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%.
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 |
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 contains 0.04% up to 0.30% carbon content. It is also known as "low carbon steel."
Medium carbon steel includes steel with carbon content ranging from 0.30% up to 0.60%.
High carbon steel includes steel with carbon content ranging from 0.60% up to 1.50%.
For rust protection and corrosion resistance, carbon steels are typically treated with hot-dipped galvanization.
Properties of alloy steel must include other elements in the standard mixture of iron and carbon.
Tool steels contain a more significant proportion of tungsten, molybdenum, chromium, and vanadium.
With seven locations serving California, Arizona, Nevada, and Northern Mexico, IMS is a full-service metal supplier that understands your needs. Our inventory of metal products includes a broad range of metal shapes and an extensive selection of alloys. At IMS, we offer the following advantages:
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.