Which statement relating to the residual magnetizing inspection method is true?

Which statement relating to the residual magnetizing inspection method is true?

• A. Subsurface discontinuities are readily apparent
• B. It is used in practically all circular and longitudinal magnetizing procedures
• C. It may be used with all steels which have been heat treated for stressed applications
• D. It cannot detect surface cracks

Answer: (C)

Residual magnetizing inspection relies on the magnetic field that remains after the magnetizing current is removed to reveal discontinuities as flux leakage at the surface. This makes it particularly effective for detecting surface-breaking and near-surface cracks in ferromagnetic materials, since the leakage path is easiest to observe where a crack interrupts the magnetic circuit. This method can be used with steels that have been heat treated for stressed applications because the material remains ferromagnetic and can retain a remanent field after magnetization. In other words, heat-treated, stressed steels can still be magnetized and inspected by looking for leakage patterns caused by flaws, so the technique is applicable to such components. Subsurface flaws are harder to detect with this approach, and surface cracks are the primary targets, which is why statements claiming it cannot detect surface cracks, or that it is applicable to all magnetic procedures, aren’t accurate.

Residual magnetizing inspection relies on the magnetic field that remains after the magnetizing current is removed to reveal discontinuities as flux leakage at the surface. This makes it particularly effective for detecting surface-breaking and near-surface cracks in ferromagnetic materials, since the leakage path is easiest to observe where a crack interrupts the magnetic circuit.

This method can be used with steels that have been heat treated for stressed applications because the material remains ferromagnetic and can retain a remanent field after magnetization. In other words, heat-treated, stressed steels can still be magnetized and inspected by looking for leakage patterns caused by flaws, so the technique is applicable to such components.

Subsurface flaws are harder to detect with this approach, and surface cracks are the primary targets, which is why statements claiming it cannot detect surface cracks, or that it is applicable to all magnetic procedures, aren’t accurate.