Iron and Steel Grading Systems
Though there are different grading systems for iron and steel, the two most commonly used in North America are the American Iron and Steel Institute (AISI) and the Society of Automotive Engineers (SAE).
American Iron and Steel Institute
The American Iron and Steel Institute (AISI) uses a four-digit numerical code to identify iron and carbon steel grades. The first two digits indicate the primary alloying elements, while the last two digits indicate the percentage of carbon in the alloy. For example, 1045 steel contains 0.45% carbon and is found in many common applications.
SAE Grading System
The Society of Automotive Engineers (SAE) uses a letter-number combination to grade steel. The first letter indicates the type of alloy, such as S for Structural and A for Alloy. The number following the letter indicates the major alloying element, and the fraction indicates the percentage of alloying element in the steel. For example, AISI 1045 steel is equivalent to SAE A51045.
Other Grading Systems
A variety of other grading systems exist for iron and steel, and may be specific to a particular region or country. The Unified Numbering System (UNS) is an example of a global alloy designation system, which was created by the Society of Automotive Engineers and the American Society for Testing and Materials. The UNS system uses a unique letter, number, and letter format to identify a specific alloy. For example, UNS S43600 is a type of stainless steel containing chromium, molybdenum, and tungsten.
Comparison Between AISI and SAE Grading Systems
The AISI and SAE grading systems are very similar, with the primary difference being the presence of an additional letter in the SAE system. Both systems use a four-digit code to indicate the major alloying element percentage in the steel. The AISI system is more commonly used in North America, while the SAE system is typically used in Europe.
Conclusion
Iron and steel grades are represented by different grading systems, such as the AISI and SAE systems, the UNS system, and various regional and country-specific systems. The AISI system is the most commonly used in North America, while the SAE system is often used in European countries. It is important to understand the differences between the systems in order to ensure that the proper grade of steel is being used.
