The GATE Grind

GATE 2025 MT – Question 45

Physical Metallurgy · Heat treatment and recrystallization · 2 marks · Multiple select

Which of the following statements is/are CORRECT when Ni is added as an alloying element to a low alloy steel?

  1. Hardenability is increased AND the Ms temperature is lowered.
  2. Hardenability is decreased AND the Ms temperature is lowered.
  3. Hardenability is increased AND the Ms temperature is raised.
  4. Hardenability is decreased AND the Ms temperature is raised.

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Correct answer: (A) Hardenability is increased AND the Ms temperature is lowered.

Explanation

Nickel stabilizes austenite and delays diffusional transformation, increasing hardenability. Austenite stabilization also lowers the martensite-start temperature Ms. Only **A** combines increased hardenability with lowered Ms.