Chinese National Standards (CNS), Japanese Industrial Standards (JIS), and the American Iron and Steel Institute (AISI) use three-digit numbers to represent different types of stainless steel, which are widely referenced in the industry. Among them, the 200 series represents chromium-nickel-manganese austenitic stainless steel, and the 400 series represents chromium stainless steel (commonly known as stainless iron), including martensitic and ferritic elements.

Additionally, classification is also based on composition, magnetism, ability to undergo heat treatment hardening, and steel grade numbers. The classification methods are shown in the table on the left: