A type of carbon steel. Carbon content of about 0.05% ~ 0.70%, individual can be as high as 0.90%. Can be divided into ordinary carbon structural steel and high-quality carbon structural steel two categories. The former contains more impurities, low price, used in places where the performance requirements are not high, its carbon content is mostly below 0.30%, the manganese content does not exceed 0.80%, the strength is low, but the plasticity, toughness, cold deformation performance is good. Except for a few cases, it is generally not used for heat treatment and is used directly. Made of strip steel, special-shaped steel, steel plate and so on. Many uses, the amount is large, mainly used in railway, bridge, all kinds of construction projects, the manufacture of various metal components under static load and not important mechanical parts and general welding parts that do not need heat treatment. High-quality carbon structural steel is pure, less impurities, good mechanical properties, and can be used after heat treatment. According to the manganese content, it was divided into two groups: common manganese content (less than 0.80%) and high manganese content (0.80% ~ 1.20%). The carbon content is less than 0.25%, most of them are used directly without heat treatment, or are treated by carburizing, carbonitriding, etc., to manufacture small and medium-sized gears, shafts, piston pins, etc.; Carbon content in 0.25% ~ 0.60%, typical steel numbers are 40, 45, 40Mn, 45Mn, etc., after tempering treatment, manufacturing a variety of mechanical parts and fasteners; Carbon content of more than 0.60%, such as 65,70,85,65 Mn, 70Mn, etc., mostly used as spring steel.
 

Chemical Composition