What is Carbon Steel?

Carbon steel is an iron-carbon alloy with a carbon content of 0.02% to 1.35%, and contains silicon, manganese, sulfur, phosphorus and other residual elements, referred to as carbon steel. Silicon and manganese in carbon steel are added as deoxidizers during steelmaking, and sulfur and phosphorus are brought in by the charge and become harmful impurities that cannot be completely removed during steelmaking. The silicon content in carbon steel is generally below 0.37%, manganese below 1.20%, sulfur below 0.055%, and phosphorus below 0.045%. Although carbon steel sometimes contains a small amount of alloying elements such as nickel, chromium, and copper, it is not deliberately added but brought in by the raw materials.

Carbon steel is currently the most widely used and most used metal material in both industry and life. It is widely used in industrial sectors such as construction, bridges, railway vehicles, automobiles, ships, machinery manufacturing, chemicals and petroleum. It can also be used to make cutting tools, molds, measuring tools and light industrial civilian products. It is easy to smelt and inexpensive, so its production and application occupy a very important position in the national economy. Carbon steel production accounts for about 90% of total steel production.

Human progress is closely linked to the smelting technology and use of metal materials, especially carbon steel. China is the earliest country to develop metal smelting technology. As early as the end of the Spring and Autumn Period (5th century BC), China’s smelting technology was very developed. And it has been in the leading position in the world before the 15th century. In the early 17th century, Northern Europe and Western Europe began to use pig iron to smelt wrought iron. In the 18th century, Britain used pig iron to smelt wrought iron in large quantities, using hydraulic blast to decarbonize the molten pig iron, and then forging and slag removal to make low-carbon wrought iron (carbon steel with low carbon content). It was not until the mid-19th century that air converters and open hearths appeared one after another that mankind truly entered the era of steel, and at the same time it also brought the world into a historical stage of rapid development.

Due to the rapid development of industrial production technology, the quality requirements for steel are getting higher and higher, and the uses are getting wider and wider. In order to meet this requirement, while vigorously developing alloy steel, various advanced industrial countries are also actively improving the quality of carbon steel and expanding the scope of use of carbon steel. Since the 1950s, oxygen top-blown converters and continuous steel casting have been promoted in steel production, creating extremely favorable conditions for improving the output and quality of carbon steel. Since the late 1970s, advanced refining technologies such as ladle argon blowing, powder spraying, and degassing, desulfurization, deoxidation, removal of inclusions and fine-tuning of composition of molten steel in containers with vacuum, inert gas or reducing atmosphere have been adopted to further improve the quality of carbon steel. After adopting these advanced technologies in oxygen top-blown converters and electric furnace production, high-quality carbon steel with low sulfur (≤5×10-6), low phosphorus (≤20×10-6), low oxygen (≤10×10-6), low hydrogen (≤0.7×10-6) and low carbon (≤15×10-6) can be produced. The use of carbon steel has gradually expanded to oil and gas pipelines, extra-thick steel plates, offshore drilling platforms and other important structural components for special purposes.