Carbon steel is a kind of steel with a carbon content between 0.02% and 2% (more than 2% is called cast iron, and less than 0.02% is called wrought iron), and very few other elements. It is also the metal material with the highest output, and the steel with relatively high other components (excluding impurities) is called alloy steel

It is usually used on metal parts that require strength, hardness and wear resistance, such as cutting tools, steel cables, piano wires, springs and knives. After machining and forming, the parts usually need to be processed and tempered. The higher the carbon content of steel, the higher its hardness, strength and wear resistance after heat treatment. Carbon steel is divided into high-carbon steel, medium-carbon steel and low-carbon steel, and each of the three types of carbon steel is divided into two types; according to characteristics, high-carbon steel is hard and brittle, and low-carbon steel is soft and ductile.