Round steel is divided into three types: hotrolled, forged and cold drawn.Hotrolled round steel is 5.5-250mm in size.Among them: 5.5-25 mm small round steel mostly in straight bundles supply, commonly used for reinforcing bars, bolts and various mechanical parts;Round steel larger than 25 mm, mainly used in the manufacture of machine parts, seamless steel tube billet, etc.

Carbon steels can be divided into low carbon steel, medium carbon steel and high carbon steel according to their chemical composition (that is, carbon content).

Common carbon structural steels, also known as ordinary carbon steels, have wide limits on carbon content, performance range, and contents of phosphorus, sulfur and other residual elements.in China and some countries according to the guarantee of delivery conditions and divided into three categories: Class A steel (Asteel) is to guarantee the mechanical properties of the steel.Class B steels (Class B steels) are steels with guaranteed chemical composition.Special steels (Class C steels) are steels that guarantee both mechanical properties and chemical composition, and are often used in the manufacture of more important structural parts.China produces and uses A3 steel (Class A No.3 steel) with a carbon content of about 0.20%, which is mainly used in engineering structures.