Chemical Compositions of SAE Carbon Steels
In 1941, the SAE Iron and Steel Division, in collaboration with the American Iron and Steel Institute (AISI), made a major change in the method of expressing composition ranges for the SAE steels. The plan, as now applied, is based in general on narrower cast or heat analysis ranges plus certain product analysis allowances on individual samples, in place of the fixed ranges and limits without tolerances formerly provided for carbon and other elements in SAE steels.
For years the variety of chemical compositions of steel has been a matter of concern in the steel industry. It was recognized that production of fewer grades of steel could result in improved deliveries and provide a better opportunity to achieve advances in technology, manufacturing practices, and quality, and thus develop more fully the possibilities of application inherent in those grades.
Comprehensive and impartial studies were directed toward determining which of the many grades being specified were the ones in most common demand, and the feasibility of combining compositions having like requirements. From these studies, the most common grades of steel have been selected and kept in the current revision. The cast or heat chemical composition limits or ranges of these grades are given in Tables 1, 2, 3A, and 3B. These cast or heat limits or ranges are subject to standard variations for product analysis as given in SAE J409. Since AISI is no longer issuing steel grade designations, grades listed in this document are SAE grades.
It is recognized that chemical compositions other than those listed in the previously mentioned tables will at times be needed for specialized applications or processing. When such a steel is required, the elements comprising the desired chemical composition are specified in one of three ways: (a) by a minimum limit, (b) by a maximum limit, or (c) by minimum and maximum limits, termed a range.