Ordinary carbon structural steel, also known as ordinary carbon steel, the carbon content, performance range, and phosphorus, sulfur and other residual elements content is relatively wide. In China and some countries according to the guarantee of delivery condition is divided into three categories: class A steel steel (class A) is to ensure that the mechanical properties of steel. B steel steel (class B) is the guarantee of the chemical composition of the steel. Special type of steel (class C) steel is both ensure the mechanical properties and guarantee the chemical