Which numerical system is utilized to designate carbon and alloy steels?

The SAE - AISI numerical system is the standard used to designate carbon and alloy steels. This system was developed by the Society of Automotive Engineers (SAE) and the American Iron and Steel Institute (AISI) to classify various grades of steel based on their chemical composition and properties.

In this system, the first digit of a carbon steel number identifies the primary alloying element, while the following digits represent the carbon content of the steel. For example, in the designation "1045," the "10" indicates it is a carbon steel, and "45" indicates that it contains approximately 0.45% carbon.

The SAE - AISI system provides a clear and systematic way for manufacturers and engineers to identify and specify the right type of steel for particular applications, ensuring consistency in material properties across various industrial sectors. This classification is crucial for ensuring the steel performs appropriately in different mechanical and structural environments.