Carbon steel is also known as the iron-carbon alloy containing less than 2% carbon WC. Generally also contain small amounts of silicon, manganese, sulfur, phosphorus and carbon steel, in addition to carbon use can be divided into carbon steel and carbon structural steel, carbon tool steel, and ease of cutting structural steel three categories. Carbon structural steel is divided into building structural steel and machinery manufacturing structural steel two kinds. According to the carbon steel, carbon content can be divided into low-carbon steel (WC ≤ 0.25%), medium carbon steel (WC0.25% - 0.6%) phosphorus, sulfur content and high-carbon steel (WC> 6%) can be divided into ordinary carbon steel (containing phosphorus, sulfur higher), high-quality carbon steel (containing phosphorus, low sulfur) and high quality steel (phosphorus, sulfur less), generally, the higher carbon content, the higher the hardness, higher strength but lower ductility.
Alloy steel refers to steel in addition to silicon and manganese as an alloying element or a deoxidizing element, but also contain other alloying elements (such as chromium, nickel, molybdenum, vanadium, titanium, copper, tungsten, aluminum, cobalt, niobium, zirconium, and other elementsetc.), and some also contain certain non-metallic elements (such as boron, nitrogen, etc.) of the steel. How much of the content of alloying elements in steel, can be divided into low-alloy steel, alloy steel and high-alloy steel.