These systems typically use a combination of letters and numbers to convey information about the chemical composition, mechanical properties, and intended use of the steel.
One of the most widely recognized systems is the American Iron and Steel Institute (AISI) and Society of Automotive Engineers (SAE) system, which uses a four-digit number plus a letter to indicate the steel's primary alloying elements. For example, 4140 is a low-alloy steel containing tantalum and molybdenum, while 304 is an austenitic stainless steel with chromium and nickel as the primary alloying elements.
In Europe, the European Committee for Standardization (CEN) has developed the EN 10025 standard for designating structural steel grades. This system uses a combination of numbers and letters, with the first two digits indicating the minimum yield strength in MPa, followed by a letter indicating the toughness or impact resistance of the steel.
For example, the AS1163 C350L0 CHS standard is specific to Australia and New Zealand and covers the requirements for hot-rolled structural steel products. The grade designations in this system include information about the steel's minimum yield strength, expected temperature range, and product form (e.g., plate, bar, or round hollow section).
Other countries and organizations, such as Japan, China, and the American Society for Testing and Materials (ASTM), have their own grading systems, which may differ in nomenclature and specific requirements. Engineers and material specifiers must be familiar with the appropriate grading system and understand the meaning of the grade designations to ensure they select the correct steel for their application.
Welded Steel Pipe
