It has the characteristics of no oxide layer on the inner and outer walls, no leakage under high pressure, high precision, high finish, no deformation in cold bending, no crack in flaring and flattening, etc. it is mainly used to produce pneumatic or hydraulic components, such as air cylinders or oil cylinders, which can be seamless tubes. Its chemical composition includes carbon C, silicon Si, manganese Mn, sulfur s, phosphorus P, chromium and chromium.