Stainless steel is divided into three categories: austenitic stainless steel (A1, A2, A3, A4, A5), ferritic stainless steel (F1) and martensitic stainless steel (C1, C4, C3).
Austenitic stainless steels contain 16%-26% chromium and up to 35% nickel, generally have the highest corrosion resistance, cannot be strengthened by heat treatment, and are nonmagnetic; the most common type is 18/8, or grade 304, That is, it contains 18% chromium and 8% nickel; typical uses include the aircraft industry, dairy and food processing industries. Austenitic stainless steel (A*-50 is softer / A*-70 is suitable for cold working / A*-80 is high strength)
Standard ferritic stainless steel contains 10.5%-27% chromium, but does not contain nickel. Due to the low carbon content (less than 0.2%), it cannot be strengthened by heat treatment and is only used in occasions where corrosion resistance is not high, such as construction and automobiles. In terms of decoration. Ferritic stainless steel (F1-45 is softer/F1-60 is suitable for cold working)
Martensitic stainless steel usually contains 11.5%-18% chromium and less than 1.2% carbon, sometimes nickel, can be strengthened by heat treatment, has moderate corrosion resistance, and is used in knives, surgical instruments, wrenches and turbines.
Stainless steel is divided according to its corrosion resistance: stainless steel (resistance to corrosion in the air) and stainless acid-resistant steel (resistance to corrosion in certain chemical media).
According to the chemical composition, it can be divided into high-chromium stainless steel (such as 4Cr13, Cr17, Cr28, Cr17Ti, etc.), chromium-nickel stainless steel (such as 0Cr18Ni9Ti, Cr18Ni12Mo2Ti), chromium-manganese-nitrogen stainless steel (such as Cr17Mn13Mo2N)