Which statement best describes Molybdenum's role in steel?

• A. Increases electrical conductivity
• B. Decreases corrosion resistance
• C. Adds strength and hardness, withstand heat and shocks, and enhances resistance to pitting corrosion in stainless steels
• D. Decreases wear resistance

Answer: (C)

Molybdenum acts as an alloying element that boosts strength, hardenability, and high-temperature performance, while also improving corrosion resistance, especially in stainless steels. Adding Mo helps steel resist heat and mechanical stresses, keeping hardness and toughness up at elevated temperatures and under shock or impact conditions. In stainless steels, Mo is particularly effective at preventing pitting and crevice corrosion in chloride environments, which is why grades containing molybdenum (like certain stainless steels) perform better in such settings. This combination of strengthening, heat resistance, and enhanced pitting resistance is why the statement describing molybdenum’s role is the best fit. The other choices don’t align with what Mo does: it doesn’t primarily increase electrical conductivity, it actually improves—not decreases—corrosion resistance, and it tends to maintain or improve wear resistance rather than decrease it.