Nickel steels with small additions of nickel (~2-5%) have which effect?

• A. increased strength and hardenability
• B. improved corrosion resistance
• C. carbon content should be no more than 0.18% if welding without preheating
• D. reduced weldability

Answer: (A)

Small additions of nickel in steel primarily boost strength and hardenability. Nickel stabilizes austenite and alters transformation kinetics, so when the steel is heat treated it can form more martensite and achieve higher strength without sacrificing ductility as much as with other alloying elements. This combination—higher strength along with enhanced ability to harden—is the main effect of nickel in the 2–5% range. Other statements are not the primary outcome here: nickel doesn’t majorly improve corrosion resistance in these steels, this question isn’t about a specific welding carbon-content limit, and nickel doesn’t reduce weldability—in fact, it often helps weld performance due to better toughness.