Carbon steel is an iron-carbon alloy with carbon content ranging from 0.0218% to 2.11%. It also contains a small amount of silicon, manganese, sulfur and phosphorus. Generally, the higher the carbon content in carbon steel, the greater the hardness and strength, but the lower the plasticity.
Classification:
(1) Carbon steel can be divided into three types according to its use: carbon structural steel, carbon tool steel and free cutting structural steel. Carbon structural steel can also be divided into engineering construction steel and machine manufacturing structural steel.
(2) According to the smelting method, it can be divided into open-hearth steel and converter steel.
(3) According to deoxidization method, it can be divided into boiling steel (F), killed steel (Z), semi-killed steel (b) and special killed steel (TZ).
(4) According to carbon content, carbon steel can be divided into low carbon steel (WC < 0.25%), medium carbon steel (WC 0.25% – 0.6%) and high carbon steel (WC > 0.6%).
(5) According to the quality of steel, carbon steel can be divided into ordinary carbon steel (containing higher phosphorus and sulphur), high quality carbon steel (containing lower phosphorus and sulphur), high quality steel (containing lower phosphorus and sulphur) and high quality steel (containing lower phosphorus and sulphur) and high quality steel.
Influencing factors:
Manganese: about 0.25%~0.80%. Solid solution strengthening, removal of FeO, reduction of brittleness of steel, and synthesis of MnS with sulfurization can alleviate the harmful effect of sulfur. It’s good.
Silicon: about 0.10%~0.40%, solid solution strengthening; except for the bad effect of FeO on steel quality, it is beneficial.
Sulphur: FeS and Fe form eutectic with low melting point (melting point is 985 C), which causes brittleness and cracking of steel during hot working at 1000 ~ 1250 (“hot brittleness”). Harmful.
Phosphorus: Strength and hardness are improved, but plasticity and toughness are reduced, “cold and brittle”. Harmful.