The ease with which a metal or metallic part can be magnetized is
called permeability. A metal that Is easy to magnetize is said to have
high permeability or to be highly permeable A metal that is difficult to
magnetize is said to have low permeability. Soft iron and iron with a
low percentage of carbon are usually easy to magnetize and are
highly permeable. Hard steel with a high percentage of carbon
content is usually hard to magnetize and, therefore, is usually lower in
permeability. Permeability and retentivity are inversely related char-
acteristics. The higher the permeability the lower the retentivity and
the lower the permeability, the higher the retentivity.
A nondestructive test using X-rays or gamma rays to determine the
subsurface condition of opaque materials. The information obtained
is permanently recorded on a specially prepared film called a
RESIDUAL MAGNETISM -
The magnetic field that remains in the parts when the magnetizing
force has been reduced to zero or the magnetizing current IS shut off
is called the residual field. The magnetism which remains is called
The property of any magnetic metal to keep or retain a magnetic field
after the magnetizing current is removed is called its retentivity.
Metals such as hard steel with a high percentage of carbon which
keep a strong magnetic field have high retentivity or are said to be
highly retentive. Those metals such as soft iron or iron with a low per-
centage of carbon which lose most of their magnetism as soon as
the magnetizing current is removed have poor retentivity.
The degree of discontinuity or defect revealed by the Inspection.
Higher sensitivity means that smaller defects are detectable
TRANSVERSE WAVE -
A wave in which particle motion Is perpendicular to the direction of
Pertains to mechanical vibrations with frequency greater than 20,000
Radiant energy produced when a suitable target is bombarded by
high voltage electrons in a vacuum. X-rays have wavelengths
between 10-11 cm and 10-6 cm
Glossary 3/(Glossary 4 blank)