The GATE Grind

GATE 2022 PI – Question 39

General Engineering · Engineering Materials · 2 marks · Multiple choice

Eutectoid steel initially fully austenitic at 750°C cools to 35°C. Match P:water quench; Q:oil quench; R:air cool; S:furnace cool, with 1:coarse pearlite; 2:fine pearlite; 3:martensite; 4:very fine pearlite.

  1. P–1,Q–2,R–3,S–4
  2. P–2,Q–3,R–4,S–1
  3. P–3,Q–4,R–2,S–1
  4. P–3,Q–4,R–1,S–2

Practise this question in The GATE Grind →

Show answer and explanation

Correct answer: (C) P–3,Q–4,R–2,S–1

Explanation

The intended cooling-rate order is water > oil > air > furnace. The supplied structure order maps fastest cooling to martensite and progressively slower pearlitic transformation to very fine, fine and coarse pearlite. Thus **P–3,Q–4,R–2,S–1, C**. Actual quench products also depend on section size and cooling history; the listed mapping is the source’s simplified model.

More Engineering Materials questions

All Engineering Materials questions →