American Iron and Steel Institute uses a three-digit number to label the stainless steel of a variety of standards.
1. Austenitic stainless steel is labeled by 200 and 300 series.
2. Ferritic and martensitic stainless steel is labeled by 400 series.Eg. some of the common austenitic stainless steels are labeled by 201, 304, 316 and 310.
3.Ferritic stainless steel is labeled by 430 and 446. Martensitic stainless steel is labeled by 410, 420 and 440C
4.Stainless steel, precipitation hardened stainless steel and the alloy with less than 50% ferrum are usually named by their proprietary name or trademark name.