Weathering steels are designed to form dense corrosion products that inhibit corrosion in some atmospheric environments. Which material category do they belong to?

• A. Weathering steels
• B. Stainless steels
• C. Carbon steels
• D. Tool steels

Answer: (A)

Weathering steels are designed to resist atmospheric corrosion by forming a dense, adherent oxide layer on the surface in suitable environments. This protective patina slows further corrosion, so they are categorized as weathering steels—an alloy-steel family engineered for controlled surface oxidation. They’re not stainless steels, which rely on a high chromium passive film to resist corrosion; they’re not carbon steels, which lack enough alloying elements to form a protective patina; and they’re not tool steels, whose primary focus is hardness and wear resistance rather than atmospheric corrosion resistance. Typical alloying elements like copper, chromium, nickel, and phosphorus enable the patina that protects the steel.