Molybdenum alloying in steel primarily increases which properties?

• A. Increases hardness and endurance limits of steel
• B. Decreases corrosion resistance at high temps
• C. Increases electrical conductivity
• D. Reduces wear resistance

Answer: (A)

Molybdenum in steel mainly boosts hardenability, which lets heat treatment produce a harder, stronger microstructure deeper in the part. That directly raises hardness and the endurance limit (fatigue resistance), so the material can withstand higher cyclic stresses before failing. Molybdenum also helps maintain strength at elevated temperatures, contributing to better wear and creep resistance in demanding service. The idea that it decreases corrosion resistance at high temperatures isn’t correct; molybdenum actually improves corrosion resistance in many stainless steels. It doesn’t increase electrical conductivity, and alloying generally lowers conductivity, not raises it. It also doesn’t reduce wear resistance; it typically improves it through the combination of higher hardness and strength.