Why steel stronger than iron?

Steel is stronger than iron primarily because of its composition as an alloy. Steel is made by combining iron with carbon, which significantly enhances its mechanical properties compared to pure iron. Here are the key reasons why steel is stronger:

1. Carbon Addition: The addition of carbon to iron creates a stronger material. Carbon atoms disrupt the uniform arrangement of iron atoms, making it harder for them to slide past each other. This disruption increases the material's resistance to deformation and stress, thereby enhancing its strength15.

2. Dislocation Prevention: In pure iron, the atoms are arranged in a uniform structure that allows them to move relatively easily under stress, a phenomenon known as dislocation. The presence of carbon in steel prevents this easy movement, resulting in a harder and more rigid material1.

3. Tensile Strength: Steel generally has a higher tensile strength than iron. While pure iron has a yield strength of around 7250 psi, steel typically ranges from 30,000 to 50,000 psi or more, depending on its composition and processing2.

4. Alloying Effects: Beyond carbon, steel can be further strengthened by adding other elements like silicon, manganese, and chromium. These additions can create various types of steel with enhanced properties, such as stainless steel, which is resistant to corrosion34.

Overall, the combination of iron and carbon, along with potential additional alloying elements, makes steel significantly stronger and more versatile than pure iron.