Carbon steel is an iron-carbon alloy containing carbon content between 0.0218% and 2.11%, also known as carbon-bearing steel. It usually contains small amounts of silicon, manganese, sulfur, and phosphorus. In general, the higher the carbon content in carbon steel, the higher the hardness and strength, but the lower the plasticity. In this article, we will take a closer look at the types of carbon steel and the applications of it.
Types of Carbon Steel – Classification by carbon content:
1. Low-carbon steel (C: ≤ 0.25%) is also known as soft steel. Low-carbon steel is easy to undergo various processes such as forging, welding, and cutting, and is commonly used for the manufacture of chains, rivets, bolts, and axles.
2. Medium-carbon steel (C: 0.25% < C ≤ 0.6%) has a wide range of 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%). It is classified into ordinary carbon structural steel and high-quality carbon structural steel based on product quality. It has good hot-working and cutting performance but poor welding performance. Its strength and hardness are higher than low-carbon steel, while its plasticity and toughness are lower than low-carbon steel. It can be used directly without heat treatment, or after heat treatment.
After quenching and tempering, medium-carbon steel has good comprehensive mechanical properties. The highest hardness that can be reached is about HB538, and the tensile strength σb is 600 to 1100MPa. Therefore, medium-carbon steel is widely used in various applications at medium strength levels, in addition to being used as building materials, it is also widely used for manufacturing various mechanical parts.
3. High-carbon steel (C: > 0.6%) is commonly known as tool steel, with a carbon content ranging from greater than 0.60% to 1.70%. It can be hardened and tempered. Tools such as hammers, pry bars, and chisels are made from steel with a carbon content of 0.75%; cutting tools such as drill bits, taps, and reamers are made from steel with a carbon content of 0.90% to 1.00%.
Types of Carbon Steel – Classification by steel quality (mainly the content of impurities)
- Ordinary carbon steel (S ≤0.055%, P ≤0.045%)
- High-quality carbon steel (S ≤0.040%, P ≤0.040%)
- High-quality carbon steel (S ≤0.030%, P ≤0.035%)
Types of Carbon Steel – Classification by Purpose
- Carbon structural steel: mainly used for bridges, ships, building components, machine parts, etc.
- Carbon tool steel: mainly used for tools, molds, measuring instruments, etc.
Grade and Application of Carbon Steel
- Ordinary carbon structural steel: Carbon structural steel is divided into five grades according to the yield strength of steel: Q195, Q215, Q235, Q255, and Q275. Each grade is divided into A, B, C, and D grades according to different qualities. Q195, Q215, and Q235 have good plasticity and can be rolled into steel plates, steel bars, steel pipes, etc. Q255, and Q275 can be rolled into formed steel, steel plates, etc.
- High-quality carbon structural steel: The steel grade is expressed as the average mass fraction of carbon. For example, 20＃, 45＃, etc. 20＃indicates a carbon content of 0.20% (20 parts per million). Uses: Mainly used for manufacturing various machine parts
- Carbon tool steel: The steel grade is expressed in terms of the average mass fraction of carbon, preceded by the letter T. For example, T9 and T12. T9 indicates a carbon content of 0.9% (9 parts per thousand). Uses: Mainly used for the manufacture of various cutting tools, measuring tools, molds, etc.
- Cast steel: The cast steel grade is preceded by the letter ZG, followed by a number representing the average mass fraction of steel (expressed in parts per million). For example, ZG25 indicates a carbon content of 0.25%. Application: Mainly used to manufacture parts with complex shapes that require certain strength, plasticity, and toughness, such as gears and couplings.
Conclusion
Thank you for reading our article and we hope it can help you to have a better understanding of the types of carbon steel. If you want to learn more about carbon steel, we would like to advise you to visit Huaxia-Steel for more information. As a leading supplier of carbon steel across the world, Huxia-Steel offers a wide range of high-quality products such as alloy steel, tool steel, stainless steel wire, sheets, strips, and stainless steel plates for global markets.
