Question

Stainless steel does not rust because :

• A. chromium and nickel combine with iron
• B. chromium forms an oxide layer and protects iron from rusting
• C. nickel present in it, does not rust
• D. iron forms a hard chemical compound with chromium present in it

Answer 1

Answer: (B)

chromium forms an oxide layer and protects iron from rusting

Stainless steel remains stainless, or does not rust, because of the interaction between its alloying elements and the environment. Stainless steel contains iron, chromium, manganese, silicon, carbon and, in many cases, significant amounts of nickel and molybdenum. Chromium present in the steel reacts with oxygen to form a protective oxide layer. The presence of the stable film prevents additional corrosion by acting as a barrier that limits oxygen and water access to the underlying metal surface. Because the film forms so readily and tightly, even only a few atomic layers reduce the rate of corrosion to very low levels.