While the SAE (Society of Automotive Engineers) and AISI (American Iron and Steel Institute) designations are often used interchangeably in the context of steel specifications, they have slightly different origins.
Understanding SAE and AISI
SAE : The Society of Automotive Engineers develops standards for the automobile industry and other related industries. SAE steel standards are widely used in North America and sometimes incorporate standards from other organizations.
AISI : The American Iron and Steel Institute was most actively involved in creating specifications for steels until the late 1990s. They developed a numbering system that classifies steels according to their chemical composition.
SAE and AISI: Unified System
In the 1990s, AISI began to transfer its materials specification responsibilities to SAE and ASTM (American Society for Testing and Materials). Today, many of the AISI standards are co-administered and co-published with SAE. This means that:
- SAE and AISI often share the same numbering system for steels. For example, 1020 means a carbon steel with approximately 0.20% carbon, and this designation is recognized by both organizations.
- Both designations are used. You may see "SAE AISI 1020" to emphasize that the steel specification meets standards recognized by both organizations.
SAE and AISI began as distinct entities; today, their steel designations are often used interchangeably to describe the same material composition. This helps to standardize steels within the industry and ensure that specifications are consistent across different sectors and applications.
In practice, the choice between using the SAE or AISI designation for steel does not depend so much on technical differences — as, as mentioned, they often refer to the same material — but rather on the industry context and the specificity of the project.
Here are some examples to illustrate where one designation may be preferred over the other, even though both may technically refer to the same type of steel:
Automotive industry
- SAE : Most common in the automotive industry due to its historical connection to the Society of Automotive Engineers. For example, engineers specifying materials for automobile components, such as axles, transmission housings, or other components that require steels with precise strength and ductility specifications, may prefer to use the SAE designation, such as SAE 1020.
General Engineering and Construction
- AISI : Used in engineering and civil construction applications where the steel specification needs to follow traditional standards to ensure compatibility and compliance with construction regulations. For example, when specifying steel for metal structures, machines, or tools, AISI 1020 can be used.
Research and Development
- SAE or AISI : In academic or research environments, both designations may be used, depending on the origin of the material or the standard adopted by the laboratory or institution. Researchers studying the properties of metallic materials may refer to a steel as SAE AISI 1020 to clearly indicate the standard composition being studied.
Supply and Commerce Industry
- Both : Steel distributors and service centers that supply materials to various industries can list steels with both the SAE and AISI designation to ensure they are meeting the expectations of customers in different industries. This can help ensure that the material provided is recognized and acceptable for a wide range of applications.
Compliance with International Standards
- AISI : In some cases, especially in international contexts where ASTM standards (which often include AISI specifications) are recognized, it may be preferable to use the AISI designation to ensure compliance and international recognition.
In conclusion, although SAE and AISI may refer to the same type of steel, the choice of which designation to use may be influenced by the industry sector, geographic context, the need to comply with specific standards, and the organization's tradition or preferences.
