What does steel do under intense heat?

When steel is subjected to intense heat, it undergoes thermal expansion, which means it expands in size. This expansion occurs because the heat causes the metal's molecules to gain energy and move more vigorously, leading to an increase in distance between them. As a result, the overall dimensions of the steel object increase as it heats up.

Understanding this property of steel is critical in firefighting operations, especially when dealing with structural integrity during a fire. As the steel beams in a building expand, they can lose strength and rigidity, potentially leading to structural failure if not properly accounted for by firefighters and engineers.

The other options presented do not accurately describe the behavior of steel under heat. For instance, steel does not contract when heated; in fact, it would contract only when cooled. Hardening typically refers to a process that involves cooling and transforming the material's properties, not heating it. Lastly, galvanization is a process involving the coating of steel with zinc to prevent rust, which does not occur simply by applying heat. Thus, the correct understanding of the behavior of steel under intense heat is crucial for ensuring safety and mitigating risks in firefighting scenarios.