Which material makes stainless steel rust resistant?

Stainless steel is known for its exceptional resistance to rust and corrosion, primarily due to the presence of chromium in its composition. When chromium is added to steel, it reacts with oxygen in the environment to form a thin layer of chromium oxide on the surface of the steel. This layer serves as a protective barrier, preventing further oxidation and rusting of the underlying metal. This property is what distinguishes stainless steel from other types of steel that lack adequate corrosion resistance.

While nickel also contributes to the corrosion resistance and overall stability of stainless steel by enhancing its structure and preventing certain types of corrosion (like stress corrosion cracking), it is chromium that is the critical element responsible for the fundamental anti-corrosive properties of stainless steel.