The GATE Grind

GATE 2025 MT – Question 29

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

Which of the following techniques can be used to detect an internal defect in a metal casting?

  1. Ultrasonic inspection
  2. Liquid (or dye) penetrant inspection
  3. Gamma-ray radiography
  4. X-ray radiography

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Show answer and explanation

Correct answer: (A) Ultrasonic inspection; (C) Gamma-ray radiography; (D) X-ray radiography

Explanation

Ultrasonic echoes reveal subsurface discontinuities; X-ray and gamma-ray radiography reveal internal attenuation differences. Dye penetrant needs a defect open to the accessible surface and cannot reveal a sealed internal flaw. Therefore **A,C,D**.