Chemistry – Metals - Alloys and their properties | e-Consult

Steel is an alloy of iron and carbon. The presence of carbon atoms within the iron crystal lattice significantly affects the metal's ability to deform.

Iron typically has a body-centered cubic (BCC) crystal structure. When carbon atoms are incorporated into this structure, they create lattice distortions. Carbon atoms are significantly smaller than iron atoms.

These smaller carbon atoms occupy positions within the iron lattice, causing the iron atoms to shift and distort. This disruption of the regular lattice structure creates stress points.

The stress points impede the movement of the iron crystal planes. The iron atoms have to work harder to slide past these distortions. This increased resistance to movement makes steel harder and stronger than pure iron.

The amount of carbon present in the iron lattice influences the extent of the distortion and therefore the hardness and strength of the steel. Higher carbon content generally leads to increased hardness and strength, but also reduced ductility. The carbon atoms effectively hinder the sliding of the iron layers, making the steel more resistant to deformation.