Carbon steel is an iron-carbon alloy with a carbon content of 0.0218 per cent to 2.11 per cent. It is also called carbon steel. Generally also contains a small amount of silicon, manganese, sulfur, phosphorus. Generally, the higher the carbon content in carbon steel, the greater the hardness, the higher the strength, but the lower the plasticity.

Five categories

(1) According to the use of carbon steel can be divided into carbon structural steel, carbon tool steel and free cutting structural steel three categories, carbon structural steel is divided into engineering construction steel and machine building structural steel two;

(2) According to the smelting method can be divided into flat furnace steel, converter steel;

(3) According to the method of deoxidation can be divided into boiling steel (F), sedentary steel (Z), semi-sedentary steel (b) and special sedentary steel (TZ);

(4) According to the carbon content of carbon steel can be divided into low carbon steel (WC ≤ 0.25%), medium carbon steel (WC0.25%-0.6%) and high carbon steel (WC ≥ 0.6%);

(5) According to the quality of steel can be divided into ordinary carbon steel (containing phosphorus, sulphur higher), high-quality carbon steel (containing phosphorus, sulphur lower) and high-quality steel (containing phosphorus, sulphur lower) and high-quality steel.