Molybdenum in stainless steel increases which property?

• A. Decreases corrosion resistance
• B. Increases electrical conductivity
• C. Increases corrosion resistance of stainless steel alloys
• D. Reduces high-temperature strength

Answer: (C)

Molybdenum boosts corrosion resistance in stainless steels, especially against localized attack in chloride environments. It helps stabilize and strengthen the passive oxide film that protects the steel, making it harder for chlorides to initiate pits or crevice corrosion. That’s why stainless grades containing molybdenum (like 316) perform better in seawater and other aggressive environments. The other ideas don’t fit: adding molybdenum isn’t used to increase electrical conductivity, and it doesn’t reduce high-temperature strength (it often helps or maintains it in many grades). So molybdenum primarily increases the corrosion resistance of stainless steel alloys.