Round steel: Round steel refers to solid strip steel with a circular cross-section. Its specifications are expressed in diameter, in millimeters (mm). For example, "50mm" refers to a round steel with a diameter of 50 millimeters.
Classification of round steel
1. Classification by chemical composition
Carbon steel can be divided into low carbon steel, medium carbon steel, and high carbon steel based on its chemical composition (i.e. carbon content).
(1) Mild steel
Also known as soft steel, low-carbon steel with a carbon content ranging from 0.10% to 0.30% is easy to accept various processing such as forging, welding, and cutting. It is commonly used in the manufacturing of chains, rivets, bolts, shafts, etc.
(2) Medium carbon steel
Carbon steel with a carbon content of 0.25% to 0.60%. There are various products such as killed steel, semi killed steel, and boiling steel. In addition to carbon, it can also contain a small amount of manganese (0.70%~1.20%). According to product quality, it is divided into ordinary carbon structural steel and high-quality carbon structural steel. Good Hot working and cutting performance, poor welding performance. The strength and hardness are higher than low-carbon steel, while the plasticity and toughness are lower than low-carbon steel. Hot rolled or cold drawn materials can be used directly without heat treatment, and can also be used after heat treatment. The quenched and tempered medium carbon steel has good comprehensive mechanical properties. The high hardness that can be achieved is approximately HRC55 (HB538), σ B is 600-1100MPa. Therefore, medium carbon steel is widely used in various applications with medium strength. In addition to being used as building materials, it is also widely used to manufacture various Machine element.
(3) High carbon steel
It is often called Tool steel. Its carbon content ranges from 0.60% to 1.70%. It can be hardened and tempered. Hammers, crowbars, etc. are made of steel with a carbon content of 0.75%; Cutting tools such as drills, taps, and reamers are made of steel with a carbon content of 0.90% to 1.00%.
2. Classification by steel quality
According to the quality of steel, it can be divided into ordinary carbon steel and high-quality carbon steel.
(1) Ordinary carbon structural steel, also known as ordinary carbon steel, has wide limitations on carbon content, performance range, and the content of phosphorus, sulfur, and other residual elements. In China and some countries, according to the guarantee conditions for delivery, it is divided into three categories: Class A steel (Class A steel) is a steel that guarantees mechanical properties. Class B steel (Class B steel) is a steel that ensures chemical composition. Special type steel (C-type steel) is a type of steel that ensures both mechanical properties and chemical composition, and is commonly used to manufacture important structural components. Currently, China produces and uses mostly A3 steel (Class A No. 3 steel) with a carbon content of around 0.20%, mainly used for engineering structures.