SAE steel grades

[1] Today steel quotes and certifications commonly make reference to both SAE and AISI, not always with precise differentiation.

For example, in the alloy/grade field, a certificate might refer to "4140", "AISI 4140", or "SAE 4140", and in most light-industrial applications any of the above is accepted as adequate, and considered equivalent, for the job at hand, as long as the specific specification called out by the designer (for example, "4140 bar per ASTM-A108" or "4140 bar per AMS 6349") is certified to on the certificate.

The AISI system uses a letter prefix to denote the steelmaking process.

Suffixes may be added to the steel grade which specify the forming process used to create a part.

The chemical requirements are loosened but hardness values defined for various distances on a Jominy test.