The GATE Grind

GATE 2024 MT – Question 50

Manufacturing Processes · Non-destructive testing · 2 marks · Multiple select

Which of the following statements is/are correct for non-destructive testing?

  1. Liquid dye penetration technique can be utilized for detecting surface cracks.
  2. In radiographic examination, internal cracks cannot be detected.
  3. Eddy current-based techniques can be used for detecting sub-surface defects in pure alumina at room temperature.
  4. Ultrasonic inspection is unsuitable for inspecting sub-surface defects in high damping capacity material (e.g., cast iron).

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Correct answer: (A) Liquid dye penetration technique can be utilized for detecting surface cracks.; (D) Ultrasonic inspection is unsuitable for inspecting sub-surface defects in high damping capacity material (e.g., cast iron).

Explanation

Dye penetrant detects surface-breaking cracks, so A is true.

Radiography can detect suitable internal discontinuities.

Eddy currents require electrical conductivity and are unsuitable for insulating alumina.

Strong ultrasonic attenuation in high-damping cast iron impairs subsurface inspection, giving D in the source’s stated comparison. **A,D**.