The GATE Grind

GATE 2021 MT – Question 18

Mechanical Behaviour of Materials · Creep · 1 mark · Multiple choice

Which statement about creep deformation is FALSE?

  1. The minimum creep rate is obtained in primary stage (stage I)
  2. Creep resistance decreases with decreasing grain size
  3. Coble creep occurs via grain-boundary diffusion
  4. Nabarro–Herring creep occurs via lattice diffusion

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Correct answer: (A) The minimum creep rate is obtained in primary stage (stage I)

Explanation

Primary creep rate decreases toward the minimum steady-state rate of secondary creep.

Hence saying the minimum occurs in primary stage is false, **A**. Coble creep uses boundaries and Nabarro–Herring creep lattice diffusion.