Which examination method uses a strong magnetizing current and a finely divided powder to detect defects?

Which examination method uses a strong magnetizing current and a finely divided powder to detect defects?

• A. Ultrasonic
• B. Liquid Penetrant
• C. Magnetic Particle
• D. Radiographic

Answer: (C)

Magnetic Particle inspection detects defects by magnetizing a ferromagnetic part with a strong current and then applying a finely divided magnetic powder. When the material has a crack or other discontinuity, the magnetic field leaks at that flaw. The powder is drawn to these leakage fields and forms a visible indication at the defect, often a bright line on the surface or just beneath it. This highlights surface and near-surface cracks effectively and can be done with either dry powder or in a wet suspension, using direct or alternating current for magnetization depending on the situation. This method is distinct because it relies on magnetization and magnetic powder, unlike other methods that use sound waves (ultrasonic), penetrating liquids and developers (liquid penetrant), or X-rays/gamma rays (radiographic). It’s best for ferromagnetic materials and requires clean surfaces to avoid false indications.

Magnetic Particle inspection detects defects by magnetizing a ferromagnetic part with a strong current and then applying a finely divided magnetic powder. When the material has a crack or other discontinuity, the magnetic field leaks at that flaw. The powder is drawn to these leakage fields and forms a visible indication at the defect, often a bright line on the surface or just beneath it. This highlights surface and near-surface cracks effectively and can be done with either dry powder or in a wet suspension, using direct or alternating current for magnetization depending on the situation.

This method is distinct because it relies on magnetization and magnetic powder, unlike other methods that use sound waves (ultrasonic), penetrating liquids and developers (liquid penetrant), or X-rays/gamma rays (radiographic). It’s best for ferromagnetic materials and requires clean surfaces to avoid false indications.