Generally, the seamless steel pipe is formed by hot-rolled or cold-rolled low-alloy structural steels such as 10, 20, 30, 35, 45 and other high-quality carbon steels such as 16Mn and 5MnV or 40Cr, 30CrMnSi, 45Mn2, and 40MnB. Seamless pipes made of low carbon steel such as 10 and 20 are mainly used for fluid conveying pipes. 45, 40Cr and other medium carbon steel seamless pipes are used to make mechanical parts, such as the force parts of automobiles and tractors. Generally, seamless steel pipes are required to ensure strength and flattening test. The hot rolled steel pipe is delivered in a hot rolled state or a heat treated state; the cold rolling is delivered in a heat treated state.