The carbon steel bar is an iron carbon alloy with carbon content ranging from 0.0218% to 2.11%. Also called carbon steel. Generally also contains a small amount of silicon, manganese, sulfur, phosphorus. The higher the carbon content in the general carbon steel, the greater the hardness, the higher the strength, but the lower the plasticity. According to the use of carbon steel can be divided into carbon structural steel, carbon tool steel and free cutting structural steel, carbon structural steel is divided into engineering construction steel and machine manufacturing structural steel two.