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AISI Steel

The American Iron and Steel Institute (AISI) uses a four-digit system, shared with SAE, to designate the chemical composition of alloy and carbon steels. The first two digits represent the primary alloying element, while the last two indicate the carbon content. This standardized approach ensures consistency across AISI and SAE specifications, often using identical steel identification numbers.

AISI Material Grading System

A basic four-digit system is used by the SAE system to designate the chemical composition of alloy steels and carbon steels. There is a possibility that AISI grades are quoted as SAE grades and very often the same steel identification number is present in AISI/SAE standards. A four-digit number is usually given to the AISI alloy steels and carbon steels. The alloying element in the AISI specification is indicated by the first two digits and the amount of carbon is indicated by the last two digits.

The chemical composition of alloy steels and carbon steels is further explained in the figure given below through a schematic representation of the AISI/SAE steel designation system.

Other steel specifications