Containing 15%~30% chromium. Its corrosion resistance, toughness and weldability increase with the increase of chromium content, and its resistance to chloride stress corrosion is better than other types of stainless steel. Crl7, Cr17Mo2Ti, Cr25, Cr25Mo3Ti, Cr28 and so on. Because of its high chromium content, ferritic stainless steel has better corrosion resistance and oxidation resistance, but its mechanical properties and process performance are poor. It is mostly used for acid-resistant structures with little stress and used as anti-oxidation steel. This kind of steel can resist the corrosion of atmospheric, nitric acid and saline solution, and has the characteristics of high temperature oxidation resistance and small thermal expansion coefficient. It can be used in nitric acid and food factory equipment, and can also manufacture parts working at high temperature, such as gas turbine parts.