Carbon steel is an iron-carbon alloy with a carbon content of 0.0218% to 2.11%. It is also called carbon steel. It generally 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 of carbon steel
- Carbon steel can be divided into three categories according to its use: carbon structural steel, carbon tool steel and free-cutting structural steel. Carbon structural steel is further divided into engineering construction steel and machine manufacturing structural steel;
- According to the smelting method, it can be divided into open-hearth steel and converter steel;
- According to the deoxidation method, it can be divided into boiling steel (F), killed steel (Z), semi-killed steel (b) and special killed steel (TZ);
- According to the carbon content, carbon steel can be divided into low carbon steel (WC ≤ 0.25%), medium carbon steel (WC0.25%-0.6%) and high carbon steel (WC≥ 0.6%);
- According to the quality of steel, carbon steel can be divided into ordinary carbon steel (higher phosphorus and sulfur content), high-quality carbon steel (lower phosphorus and sulfur content), high-grade high-quality steel (lower phosphorus and sulfur content) and special high-quality steel.
Advantages of carbon steel - High strength: Carbon steel is composed of iron and a certain amount of carbon, so it has high strength and rigidity, and can withstand greater pressure and load-bearing weight. This also makes carbon steel the first choice for structural materials such as various machinery, vehicles, roads, etc.
- Good wear resistance: The carbon element contained in carbon steel can increase the surface hardness, enabling it to effectively resist friction and wear. Therefore, carbon steel is often used to manufacture products with high wear resistance requirements such as knives, bearings, and weapons.
- Low price: Compared with other metal materials, carbon steel has a lower cost, so it is widely used in fields where manufacturing costs are more sensitive. For example, it is reflected in automobiles, construction, furniture, etc.
Hardness of carbon steel
The hardness of carbon steel depends on its carbon content and whether it has been heat treated. Based on the information provided, the following conclusions can be drawn:
The hardness of low carbon steel (usually with a carbon content of less than 0.10%) is generally between 120 and 150 HB.
The hardness of medium carbon steel (usually with a carbon content of 0.25%~0.60%) is usually between 150~200HB.
The hardness of high carbon steel (usually with a carbon content of 0.60%~1.0%) is generally between 200~300HB.
In addition, there are specific types of carbon steel, such as 45# steel and 20# steel, whose hardnesses are HRC 20-25 and HRC 15-25, respectively, and the corresponding HB values are 187-229 and 121-207. These data show that different types and contents of carbon steel have different hardness ranges.