There are many ways to classify stainless steel. According to the structure at room temperature, there are martensitic, austenitic, ferritic and duplex stainless steels; according to the main chemical components, they can be basically divided into two major systems: chromium stainless steel and chromium-nickel stainless steel; There are nitric acid-resistant stainless steel, sulfuric acid-resistant stainless steel, seawater-resistant stainless steel, etc., which can be divided into pitting corrosion-resistant stainless steel, stress corrosion-resistant stainless steel, intergranular corrosion-resistant stainless steel, etc. according to the type of corrosion resistance; Magnetic stainless steel, free cutting stainless steel, low temperature stainless steel, high strength stainless steel, etc. Due to its excellent corrosion resistance, formability, compatibility and toughness in a wide temperature range, stainless steel has been widely used in heavy industry, light industry, daily necessities industry and building decoration industries. .