Rolled Steel vs Carbon Steel: What Are the Differences and Similarities?

In the fields of metal processing and materials science, rolled steel and carbon steel are two frequently mentioned concepts, but they represent different aspects. Rolled steel refers to a processing method, while carbon steel denotes a specific type of material.

一、Definitions and Classifications

Rolled Steel: A Processing Method

         Rolled steel (steel rolling) is a pressure processing method that changes the shape of steel ingots or billets between rotating rolls. The primary purpose of this process is to obtain the desired shape and size, such as steel plates, strip steel, wire rods, and various structural steels. Additionally, rolling can improve the internal quality of steel, making it more suitable for various applications.

Carbon Steel: A Material Type

         Carbon steel is an alloy steel whose main components are iron and carbon. The carbon content affects the hardness, strength, and plasticity of steel. Based on carbon content, carbon steel can be classified into low-carbon steel, medium-carbon steel, and high-carbon steel.

• Low-carbon Steel: With a carbon content of less than 0.25%, it exhibits good plasticity and toughness, making it easy to form and weld. It is commonly used in bridges, building structures, and automobile manufacturing.

• Medium-carbon Steel: With a carbon content between 0.25% and 0.60%, it combines strength and plasticity, suitable for manufacturing rails, gears, and shafts.

• High-carbon Steel: With a carbon content greater than 0.60%, it has high hardness and strength but lower plasticity and toughness, making it suitable for manufacturing springs and high-hardness cutting tools.

二、Production Processes

Rolled Steel: The rolling process can be divided into hot rolling and cold rolling. Hot rolling involves heating steel billets to a certain temperature and then processing them through rolling mills to achieve the desired dimensions. Cold rolling, on the other hand, processes steel plates at room temperature, characterized by a smooth surface and high dimensional accuracy.

Carbon Steel: The production process includes ironmaking, steelmaking, and shaping. During the steelmaking stage, steel with different carbon contents is obtained by adjusting raw material proportions and smelting conditions.

三、Properties and Applications

Rolled Steel: Steel after rolling has advantages such as high flatness, hardness, strength, and corrosion resistance. Rolled steel has a wide range of applications in modern industrial production, including the production of various metal products such as steel plates, ship plates, pipes, and rails. By controlling the temperature and rolling process, the properties of steel can be adjusted, increasing its strength and hardness, and improving its quality and service life.

Carbon Steel: The properties of carbon steel depend not only on its carbon content but also on other elements such as manganese, silicon, sulfur, and phosphorus. Manganese enhances hardness, improves weldability, and impacts toughness; silicon increases strength but excessive amounts reduce plasticity and toughness; sulfur and phosphorus are typically impurities that, in excess, degrade steel performance. Carbon steel is one of the most commonly used materials in industry and construction due to its relatively low cost and good processability. However, its corrosion resistance is poor, but surface treatments such as galvanizing or coating with special paints can enhance its resistance to environmental factors to some extent.

四、Differences and Connections

The main difference between rolled steel and carbon steel is that rolled steel is a processing method, while carbon steel is a type of material.

The rolling process can be applied to various steels, including carbon steel, to change their shapes and sizes and improve their properties. Carbon steel is a commonly used raw material in the rolling process.

In practical applications, rolled steel and carbon steel are often interrelated. For example, carbon steel billets from steel plants need to undergo the rolling process to become qualified steel plates, pipes, and other products. At the same time, the rolling process can adjust the properties of carbon steel to meet different application requirements.

In summary, although rolled steel and carbon steel represent different concepts, they both play important roles in the fields of metal processing and materials science. Understanding their differences and characteristics helps to better understand and apply these two technologies.