Which statement best describes magnetic particle testing?

Which statement best describes magnetic particle testing?

• A. It detects only near-surface flaws and requires magnetizable metals.
• B. It detects flaws anywhere in the material.
• C. It cannot detect surface flaws.
• D. It is a destructive test.

Answer: (A)

Magnetic particle testing works by magnetizing the part and applying iron particles so that any defect that disturbs the magnetic field creates a leakage field that draws the particles to the flaw. The visible indication typically appears at flaws that are open to the surface or very near it, which makes this method especially effective for locating cracks and other surface-breaking defects. It also requires the material to be magnetizable—ferromagnetic metals like steel and iron respond to the magnetization and reveal leakage at flaws, while non-magnetic materials don’t produce reliable indications. That’s why this statement is the best description: it emphasizes the near-surface nature of detectable flaws and the need for magnetizable metals. It’s not a method that detects flaws anywhere inside the material, it can reveal surface flaws, and it is nondestructive rather than destructive.

Magnetic particle testing works by magnetizing the part and applying iron particles so that any defect that disturbs the magnetic field creates a leakage field that draws the particles to the flaw. The visible indication typically appears at flaws that are open to the surface or very near it, which makes this method especially effective for locating cracks and other surface-breaking defects. It also requires the material to be magnetizable—ferromagnetic metals like steel and iron respond to the magnetization and reveal leakage at flaws, while non-magnetic materials don’t produce reliable indications.

That’s why this statement is the best description: it emphasizes the near-surface nature of detectable flaws and the need for magnetizable metals. It’s not a method that detects flaws anywhere inside the material, it can reveal surface flaws, and it is nondestructive rather than destructive.