Quality carbon structural steel is the carbon content less than 0.8% of carbon steel, this steel contains sulfur, phosphorus and non-metallic inclusions less than carbon steel, the more excellent mechanical properties.
 Quality carbon structural steel (GB/T699-1999): steel, in addition to containing carbon (C) elements and a certain amount of oxygen and silicon (Si) (generally not more than 0.40%), manganese (Mn) (generally not more than 0.80 % to 1.20% may be higher) alloying elements, but without other alloying elements (except for the residual element). Such steels must also ensure that the chemical composition and mechanical properties. The sulfur (S), phosphorus (P) the general control of impurity elements 0.035% or less. If the control is called below the 0.030% senior high-quality steel, the grade should be added after "A", such as 20A; if P control of 0.025% or less, S 0.020% below control, said the super high-quality steel, the grade should be followed Add "E" to show the difference. For raw materials into steel by the remnants of other alloying elements such as chromium (Cr), Nickel (Ni), copper (Cu) content such as the general control of Cr ≤ 0.25%, Ni ≤ 0.30%, Cu ≤ 0.25%. Some grades of manganese (Mn) content reached 1.40%, known as manganese steel.

 Such adjustment is to rely on carbon steel (C) the amount to improve the mechanical properties of steel, therefore, according to the level of carbon content, these steels can be divided into:

Low carbon steel - generally less than 0.25% carbon content, such as 10, 20 steel; in carbon - carbon content is generally between 0.25 to 0.60%, such as 35,45 steel; high-carbon steel - carbon content is generally greater than 0.60%. Such is generally not used in the manufacture of steel pipe.

In fact, the carbon content between them, and no clear boundaries. Such a large steel production, uses a wider, more generally rolling (forging) made of round, square, flat and other profiles, plates and seamless steel pipe. Mainly for the manufacture of the general structure and mechanical parts and components and building structures and pipe conveying fluid. According to requirements, and sometimes need to heat treatment (normalizing or quenching and tempering) before use.


Uses:

     Parathion-quality carbon structural steel containing less than 0.035%, mainly used to make the more important parts.

 According to GB699-88, high-quality carbon structural steel grades with two digits, that is, the average carbon content in steel extremely digits. For example, 20 gauge steel that the average carbon content of 0.20% of high-quality carbon steel. For the boiling steel in the rear with F, such as 10F, 15F and so on. 08,10,15,20,25 and other grades are low-carbon steel, the plastic is good, easy drawing, stamping, extrusion, forging and welding.

 Quality carbon structural steel grades are in 08,10,15,20,25 and other low-carbon steel, the plastic is good, easy drawing, stamping, extrusion, forging and welding. 20 steel the most widely used to manufacture screws, nuts, washers, small axes and stamping parts, welding parts, sometimes used in the manufacture carburizing parts. 30,35,40,45,50,55 and other brands are in carbon steel, because steel pearlite content increased, compared with its strength and hardness increase, the hardness after quenching can be increased significantly. Among them, the most typical of 45 steel, which not only strength, high hardness and good ductility and toughness of both, that is excellent overall performance. 45 steel in the mechanical structure of the most widely used to manufacture shaft, screw, gear, rod, sleeve, keys, screws and nuts and other important. 60,65,70,75 and other grades are high carbon steel. They have been hardened, tempered only the strength, hardness, and good flexibility, used to create a small spring, spring, wire rope, roller and so on.