There are many classification methods for stainless steel. According to the structure classification at room temperature, there are martensite, austenite, ferrite and duplex stainless steel; According to the main chemical composition classification, it can be basically divided into two major systems: chromium stainless steel and chromium nickel stainless steel; According to the purpose, there are standard components such as nitric acid resistant stainless steel, sulfuric acid resistant stainless steel, seawater resistant stainless steel, etc. According to the type of corrosion resistance, it can be divided into pitting resistant stainless steel, stress corrosion resistant stainless steel, intergranular corrosion resistant stainless steel, etc; Classified by functional characteristics, it can be further divided into non-magnetic stainless steel, easy cutting stainless steel, low-temperature stainless steel, high-strength stainless steel, and so on. Due to its excellent corrosion resistance, formability, compatibility, and strong toughness over a wide temperature range, stainless steel has been widely used in industries such as heavy industry, light industry, daily necessities, and building decoration.