The GATE Grind

GATE 2020 MT – Question 19

Manufacturing Processes · Non-destructive testing · 1 mark · Multiple choice

Dye-penetrant testing for flaws is based on

  1. Magnetism
  2. Sound propagation
  3. X-ray absorption
  4. Capillary action

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Show answer and explanation

Correct answer: (D) Capillary action

Explanation

A wetting penetrant is drawn into surface-connected discontinuities by capillary action. Excess penetrant is removed and developer brings trapped liquid back to the surface to make an indication visible. Thus D. The test detects accessible surface flaws; it is distinct from magnetic, ultrasonic and radiographic techniques.

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