How does a relatively small amount of chromium prevent steel from rusting?

Question

How does a relatively small amount of chromium prevent steel from rusting?

In: 573

Answer 1

This what is known as a sacrificial element. As stated elsewhere, the chromium reacts to oxygen at a faster rate than steel or iron. The chromium bond doesn’t force an expansion like oxygen to iron does. This creates a shield that prevents the oxygen molecules reaching the iron and creating rust.

Several other elements are used in such a manner including tin.