Introduction to the SAE AMS Designation System

---

Overview of the SAE AMS Designation System

The SAE AMS designation system uses a numeral index to identify the compositions of alloy steels. This system allows for the use of numerals that partially describe the material's composition. The first digit in the numeral denotes the steel's type. For instance, "1" indicates carbon steel, "2" represents nickel steel, and "3" refers to nickel-chromium steel, among others.

Understanding Steel Composition and Alloy Classification

In basic alloy steels, the second digit typically represents the approximate percentage of the predominant alloying element. For example, "2340" indicates a nickel steel with approximately 3% nickel (ranging from 3.25% to 3.75%) and 0.40% carbon (ranging from 0.38% to 0.43%).

The last two digits usually denote the carbon content in hundredths of a percent. For instance, "xx45" means a steel with 0.45% carbon.

How the SAE AMS System Classifies Carbon Content

For example, the AISI 4340 designation represents a nickel-chromium-molybdenum steel with 1.8% nickel, 0.8% chromium, 0.25% molybdenum, and 0.4% carbon. Similarly, the 9260 steel is a spring steel containing 2.5% silicon, 0.9% manganese, and 0.6% carbon. The 52100 designation refers to ball bearing steel, which contains 1.45% chromium and 1.0% carbon.

Deviation from Standard SAE AMS System for Special Alloys

In some instances, to avoid confusion, the SAE AMS system departs from its standard format. For certain alloys, especially corrosion-resistant and heat-resistant steels, the second and third digits may differ from the standard pattern to ensure proper identification.

Applications of the SAE AMS Designation System

The SAE AMS designation system is extensively used across various industries, including the automotive, aerospace, and manufacturing sectors. It enables precise identification and classification of alloy steels based on their composition, making it a critical tool for engineers and metallurgists.

Click on the link to see a list of SAE AMS standards covering the following material categories:

Group of standards for stainless steels: Part One

Group of standards for stainless steels: Part Two

Group of nickel alloys/heat resistant nickel alloys

Group of standards for iron and steel castings

Group of standards for forgings

Group of standards for coated steels & welding and filler materials