·
Acoustic Impedance (Z)- The resistance of a material to the
passage of sound waves. The value of this material property is the product of
the material density and sound velocity. The acoustic impedance of a material
determines how much sound will be transmitted and reflected when the wave
encounters a boundary with another material.
·
Angle of Incidence - The angle between the direction of
propagation of an electromagnetic or acoustic wave (or ray) incident on a body
and the local normal to that body.
·
Angle of Reflection - The angle between the direction of
propagation of an electromagnetic or acoustic wave (or ray) reflected by a body
and the local normal to that body.
·
Angle of Refraction - The angle between the direction of
propagation of an electromagnetic or acoustic wave (or ray) refracted by an
optically homogeneous body and the local normal to that body.
·
Annealing - Any treatment of metal at an
elevated temperature for the purpose of softening, removing residual stresses,
recrystallization and other purposes.
·
Anode - (1) The positive terminal or the
collector of electrons in an electrical system (i.e. the positive terminal of a
battery) (2) The electrode at which oxidation or corrosion occurs. It is the
opposite of cathode.
·
Attenuation - The reduction in the level of a
quantity, such as the intensity of a wave or radiation.
·
Beam Spread - The divergence of the sound beam as
it travels through a medium. Specifically, the solid angle that contains the
main lobe of the beam in the far field.
·
Calibration - The process whereby the magnitude of
the output of a measuring instrument is related to the magnitude of the input
force driving the instrument.
·
Capillary Action - The phenomenon of a liquid such as
water spontaneously creeping up thin tubes and fibers, this is caused by
adhesive and cohesive forces and surface tension.
·
Coercive Force - The reverse magnetizing force
necessary to remove residual magnetism and demagnetize the part
·
Compton Scattering - A process through which radiation is
absorbed by the material it penetrates.
·
Decay - The gradual reduction of the
quantity of some substance or energy form to zero.
·
Decay Radioactive - The spontaneous change of an atomic
nucleus and the emission of a particle or a photon.
·
Demagnetization - The process of removing existing
magnetism from a part.
·
Dwell Time - The period of time wherein penetrant
or developer is in contact with the surface of the part. Drain time is
considered to be a portion of the dwell time. Synonymous with penetration time
or emulsifier time.
·
Echo - A signal indicating reflected
acoustic energy.
·
Emulsifiers - An additive that promotes the
formation of a stable mixture between two liquids like oil and water.
·
Exposure - The time which radiation is being
exposed to something.
·
Etching - Subjecting the surface of a metal to
preferential chemical or electrolytic attack in order to reveal structural
details.
·
Fatigue Cracks - Cracks in a material formed from
repeated stress, none of which exceeded the maximum stress of the material.
·
Ferrous - Describing a metal that is more than
50% iron, such as steel, stainless steel, cast iron, ductile (nodular) cast
iron, etc.
·
Field Intensity - A term used to describe the strength
of the electromagnetic field.
·
Fluorescence, Penetrant - Property of emitting light as the
result of, and only during the absorption of radiation from some other energy
source.
·
Fluorescent - A bright vivid color that glows
under a black light.
·
Flux Density - The number of flux lines per unit of
area, measured at right angles to the direction of the flux. It is the measure
of magnetic field strength.
·
Flux Leakage - Flux, or lines of force, leaking
from pole to pole outside a magnet.
·
Focal-Film Distance (ffd) - The distance in inches between the
focal spot of the x-ray tube, or the radiation source, and the film.
·
Half-life - The amount of time it takes for half
of the atoms in a given mass to decay.
·
Half Value Layer (HVL) - The depth in given material at which
the radiation intensity becomes one half that at the surface of the material.
·
Half Wave Rectified (ac) - When a single phase alternating
current is rectified in the simplest manner, the reverse half of the cycle is
blocked out entirely. The result is a pulsating unidirectional current with
intervals when no current at all is flowing. This is often referred to as
"half-wave" or as pulsating direct current.
·
Hall Effect - An effect used in the measurement of
magnetic fields.
·
Heat Treatment - Heating and cooling a metal or alloy
in such a way as to obtain desired conditions or properties.
·
Heat Treat Verification - To verify the material has gotten
the proper heat treatment a conductivity measurement can be taken.
·
Heat-Affected Zone - That portion of the base metal which
was not melted during brazing, cutting or welding, but whose microstructure and
physical properties were altered by the heat.
·
Henries (H) - A unit of measure for induction.
·
Hertz - One cycle per second.
·
Hydrophilic Emulsifiers - A process to remove the excess
penetrant with mechanical and chemical action but no diffusion takes place.
Hydrophilic emulsifiers are basically detergents that contain solvents and
surfactants.
·
Impedance - The total opposition in an
electrical circuit to flow of alternating current.
·
-
Represents the combination of those electrical properties that affect the flow
of current through the circuit.
·
Inductance - Ratio of the total magnetic
flux-linkage in a coil to the current flowing through the coil.
·
Intensifying Screen - A layer of material placed in
contact with the film to increase the effect of the radiation, thus shortening
the exposure.
·
Intensity - The amount of energy a sound has
over an area. The same sound is more intense if you hear it in a smaller area.
In general, sounds with a higher intensity are louder.
·
Ionization - This process of radiation
absorption.
·
Isotope - One of two or more atoms of the same
element that have the same number of protons in their nucleus but different
numbers of neutrons. Most elements have more than one naturally occurring
isotope.
·
Joint Efficiency - The strength of a welded joint
expressed as a percentage of the strength of the unwelded base metal.
·
Joint Penetration - The distance weld metal and fusion
extend into a joint.
·
Lack of Fusion - Discontinuity due to lack of union
between weld metal and parent metal.
·
Lamb Wave -A type of ultrasonic wave propagation
in which the wave is guided between two parallel surfaces of the test object.
The mode and velocity depend on the product of the test frequency and the
separation between the surfaces.
·
Longitudinal Waves - Commonly used term for compressional
wave.
·
Magnetic
Domain - A region in which the magnetic fields of atoms are grouped together
and aligned.
·
Magnetic
Field - The space in which a magnetic force is exerted. This space exists
within and around a magnetized material and a conductor carrying electrical
current.
·
·
Magnetic Field Strength - The measured intensity of a magnetic
field at a specific point. Usually expressed in amperes/meter or oersteds.
·
Magnetic Flux - A measure of quantity of magnetism,
taking account of the strength and the extent of a magnetic field. The total
number or lines of force existing in a magnetic circuit.
·
Magnetic Flux Density (B) - The normal magnetic flux per unit
area. Usual expressed in Tesla or Gauss.
·
Magnetic Lines of Force - Imaginary lines in the magnetic
field indicating how strong the magnetic force is (the closer together the
lines, the stronger the force).
·
Magnetic Domain - A region in which the magnetic
fields of atoms are grouped together and aligned.
·
Magnetic Field - The space in which a magnetic force
is exerted. This space exists within and around a magnetized material and a
conductor carrying electrical current.
·
Magnetic Field Strength - The measured intensity of a magnetic
field at a specific point. Usually expressed in amperes/meter or oersteds.
·
Magnetic Flux - A measure of quantity of magnetism,
taking account of the strength and the extent of a magnetic field. The total
number or lines of force existing in a magnetic circuit.
·
Magnetic Flux Density (B) - The normal magnetic flux per unit
area. Usual expressed in Tesla or Gauss.
·
Magnetic Lines of Force - Imaginary lines in the magnetic
field indicating how strong the magnetic force is (the closer together the
lines, the stronger the force).
·
Pair Production - An absorption process for X and
gamma radiation in which the incident photon is annihilated in the vicinity of
the nucleus of the absorbing atom, with subsequent production of an electron
and positron pair.
·
Parameter - A material property or instrument
variable.
·
Particles - Fundamental units of matter and
energy.
·
Particle Motion - Movement of particles of material
during wave propagation.
·
Particulate Radiation - A stream of atomic or subatomic
particles.
·
Penetrability - The property of a penetrant that
causes it to find its way into very fine openings, such as cracks.
·
Penetrometer - A device for measuring the
penetrating power of radiation.
·
Photoelectric (PE) - A substance is photoelectric if it
ejects electrons when light strikes it.
·
Photoelectric absorption - A process by which electromagnetic
radiation imparts energy to matter.
·
Photoelectric Effect - When charged particles are released
from a material when it absorbs radiant energy.
·
Propagation - Advancement of a wave through a
medium.
·
Proportional Limit - The maximum stress at which strain
remains directly proportional to stress; the upper end of the straight-line
portion of the stress-strain or load-elongation curve.
·
Radiation Sources - An object that emitted radiation.
·
Radioactive - Atoms which are energetically
unstable and decay to a stable condition by emitting radiation are said to be
radioactive.
·
Radioactive Activity - The amount of radiation an object is
emitting.
·
Radioactive Contamination - Deposition of any radioactive
material in any place where it is not desired, particularly where it may be
harmful.
·
Radioactive Decay - The process by which the nucleus of
a radioactive isotope decomposes and releases radioactivity.
·
Radioactive Elements - Elements that naturally emit
radiation when the nucleus of the atoms disintegrate or decay.
·
Scattering - Random reflection of ultrasonic
waves by small discontinuities or surface irregularities.
·
Transducer - An electroacoustic or
magnetoacoustic device containing an element for converting electrical energy
into acoustical energy and vice versa. See search unit.
·
Transducer Element - The component in a transducer that
actually converts the electrical energy into acoustical energy and vice versa.
The transducer element is often made of a piezoelectric material or a
magnetostrictive material.
·
Transformer - A transformer is simple a device
that transforms electricity form one voltage to another.
·
Transgranular Fracture - Through, or across, the crystals
or grains of a metal. Same as transcrystalline and intracrystalline. Contrasted
to intergranular fracture. The most common type of transgranular fracture are
fatigue fractures. Cleavage fractures, dimpled rupture fractures, and shear
fractures.
·
Transient Currents - These currents are of short
duration, generated by sudden changed in the electrical or magnetic conditions
existing in an electrical or magnetic circuit.
·
Ultrasonic
Spectrum - Usually, the frequency range from 20,000 to 107 hertz. But may
extend much higher in special applications.
·
Ultrasonic
Spectroscopy - Analysis of the frequency content of an acoustic wave. Generally
performed mathematically using a fast Fourier transform.
·
Ultrasonic
Testing - The transmission of high-frequency sound waves into a material to
detect imperfections or to locate changes in material properties.
·
Ultrasonic Vibrations - Vibrational waves of a frequency
above the hearing range of the normal human ear are referred to as ultrasonic,
and the term therefore includes all those waves of a frequency of more than
approximately 20,000 cycles per second. Also known as ultrasonic waves.
·
Ultrasonic Waves - Sound waves too high in frequency
for humans to hear.
·
Ultrasonically Sound Material - A material having no discontinuities
which cause discernible ultrasonic indications at the required test sensitivity
level.
·
Ultrasound - A test using ultrasonic waves to
create an image of the inside of an object.
·
Ultraviolet Light - Light lying just beyond the violet
end of the visible spectrum and having wavelengths shorter than approximately
4,000 angstroms.
·
Ultrasonic - A term referring to acoustic
vibration frequencies greater than about 20,000 hertz.
·
Velocity - Distance traveled per unit time.
·
Vertical Limit - The readable level of vertical
indication on an A-scan.
·
Vibration - A rapid back and forth motion of a
particle or solid.
·
Vibrational Motion - Moving backward and forward, like a
pendulum.
·
Virgin curve - The original magnetizing curve of a
material.
·
Viscosity - Resistance to flow of a liquid
·
X-rays - A form of electromagnetic radiation
with wavelengths shorter than those of ultraviolet light.
·
Yield Point - The first stress in a material, less
than the maximum attainable stress, at which an increase in stress. Not a
general term or property; only certain metals exhibit a yield point.
·
Yield Strength - The stress at which a material
exhibits a specified deviation is usually 0.2% for most metals. A general term
or property, preferred to yield point.
·
Young's Modulus - Same as modulus of elasticity.
