Steel Institute

The American Iron and Steel Institute uses three digits to mark various standard grades of wrought stainless steel. Among them: austenitic stainless steel with the 200 and 300 series of digital marking. Ferritic and martensitic stainless steel with the number of series 400. For example, some of the more common austenitic stainless steel is 201, 304L, 316 and 310 as a marker. Ferritic stainless steel is 430 and 446 for marking, martensitic stainless steel is 410, and 420 440C markers, dual phase (ferrite). Stainless steel, precipitation hardening stainless steel and high alloy steel containing less than 50% are usually patented or trade name.