Nickel steels with small nickel additions show 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. decreased weldability

Answer: (A)

Nickel in small amounts strengthens steel and boosts its hardenability. It does this in two ways: first, nickel atoms dissolve in the iron lattice and provide solid-solution strengthening, which raises the material’s strength. Second, nickel acts as an austenite stabilizer, slowing the transformation from austenite to pearlite or bainite during cooling. This delays transformation and allows more martensite to form when the steel is quenched, increasing hardenability. So, steels with small nickel additions become both stronger and better able to develop hardness in thicker sections when heated and quenched. The other effects mentioned are not the primary outcome of these small nickel additions, so the best answer highlights the increase in strength and hardenability.