Which type of steel is characterized by its composition of iron and carbon without additional materials?

Carbon steel is characterized by its composition of iron and carbon, where the carbon content typically ranges from less than 0.1% to about 2% by weight. This type of steel does not contain substantial amounts of other alloying elements, which sets it apart from other types of steel like alloy steel, which includes additional elements to enhance specific properties.

In carbon steel, the properties are primarily influenced by the amount of carbon present. Increased carbon content can lead to improved hardness and tensile strength but may also reduce ductility. Despite this, carbon steel is commonly used in a variety of applications due to its balance of strength, ductility, and affordability.

Mild steel, a subset of carbon steel, has a lower carbon content (typically under 0.25%) and is known for its excellent weldability and malleability. While it is indeed a type of carbon steel, the term "carbon steel" more broadly encompasses steels across the carbon content spectrum, making it the most accurate choice when considering the question's criteria of having no additional materials.

Alloy steel and stainless steel contain significant amounts of other metals or elements that change their properties for specific uses, distinguishing them from the simpler composition of carbon steel.