Steel is an alloy primarily composed of iron and a small percentage of which element?

Steel is primarily composed of iron with a small percentage of carbon, which is crucial for its properties. The addition of carbon helps to enhance the strength and hardness of the iron. This process occurs because carbon atoms fit into the iron crystal lattice, which not only affects the way the iron atoms bond with each other but also alters the overall structure of the metal. The varying amounts of carbon can lead to different types of steel, with properties tailored for specific applications, such as in construction or manufacturing.

While other elements like nickel, chromium, and manganese can be alloying agents in different steel types, they are used to impart additional specific properties rather than being a primary component like carbon. Nickel, for example, increases toughness and resistance to corrosion; chromium enhances hardness and improves wear resistance; and manganese can increase hardenability and strength. However, the foundational element that defines steel is indeed iron combined with carbon.