There are several different grades of round steel. Mild steel, also known as low - carbon steel, is one of the most common grades, with a low carbon content, providing good formability and weldability. Medium - carbon steel has a higher carbon content, offering a balance between strength and ductility, suitable for parts that require more strength. High - carbon steel, with its high carbon content, is used for applications where high hardness and wear resistance are needed, like cutting tools. Alloy steel grades contain additional alloying elements such as chromium, nickel, and molybdenum, which enhance specific properties, such as corrosion resistance or high - temperature strength.