High quality carbon structural steel

High quality carbon structural steel (GB/T699-1999) in addition to contain C element in steel, a certain amount of Si element for deoxidation (generally no more than 0.40%), and Mn (generally no more than 0.80%, up to 1.20%) alloy elements, excluding other alloying elements (except for residual element). This kind of steel must ensure the chemical composition and mechanical properties at the same time. Its S and P content of impurity elements in general are controlled under 0.035%. If controlled under 0.030% called high quality steel, its brand behind should add an "A", such as 20 A; If P is controlled under 0.025%, S controlled below 0.020%, called special high-quality steel, the brand should be added behind the "E" in order to show the difference.For the other residual alloying elements taken by the raw materials into the steel, such as Cr, Ni, Cu and so on, the content of general controlled: Cr≤0.25%
Ni≤0.30%
Cu≤0.25%. Some brands of Mn content is up to 1.40%, known as Mn steel.This kind of steel relied on adjusting the amount of carbon (C) to improve the mechanical properties of steel, therefore, according to the carbon content, this kind of steel can be divided into: low carbon steel, carbon content, generally less than 0.25%, such as 10, 20 steel, etc.Medium carbon steel, carbon content is in commonly between 0.25 ~ 0.60%, 35, 45 steel, etc.;High carbon steel, carbon content is generally greater than 0.60%.This kind of steel is generally not used in the manufacture of steel pipe.Actually, there are no obvious boundary of the carbon content.Such steel production is bigger, with broad application, rolling (forging) more commonly made into round, square, flat profiles, such as plate and seamless steel pipe. Mainly used in the manufacture of general structure and the mechanical structure parts, components and building structure and pipe conveying fluid.