Stainless steel is often classified according to the state of organization: martensitic steel, ferritic steel, austenitic steel and so on. In addition, it can be divided into: chromium stainless steel, chromium-nickel stainless steel and chromium-manganese-nitrogen stainless steel, etc. according to the composition.
1, ferritic stainless steel: containing 12% to 30% chromium. Its corrosion resistance, toughness and weldability with the increase in chromium content, chloride stress corrosion resistance is better than other types of stainless steel. Belonging to this category are Crl7, Cr17Mo2Ti, Cr25, Cr25Mo3Ti, Cr28 and so on. Ferritic stainless steel because of the high chromium content, corrosion resistance and oxidation resistance are relatively good, but the mechanical properties and process performance is poor, and is used for not much force acid-resistant structure and for the use of oxidation-resistant steel. This type of steel can resist the atmosphere, nitric acid and brine solution corrosion, and has a good high temperature oxidation resistance, small coefficient of thermal expansion, etc., used in nitric acid and food factory equipment, can also make parts working at high temperature, such as gas turbine parts. 2, austenitic stainless steel: contains more than 18% chromium, also contains about 8% nickel and a small amount of molybdenum, titanium, nitrogen and other elements. Comprehensive performance is good, can be resistant to a variety of media corrosion. Austenitic stainless steel commonly used grades are 1Cr18Ni9, 0Cr19Ni9, etc. 0Cr19Ni9 steel wC <0.08%, the steel number marked as "0". This type of steel contains a large amount of Ni and Cr, so that the steel at room temperature austenitic state. This type of steel has good plasticity, toughness, weldability and corrosion resistance,