NDT
Glossary
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T
- Tangential
- See circumferential.
- Target
- A material bombarded by any radiation, as the target is bombarded by electrons
in an x-ray tube.
- Temporary
Magnet
- A body of a soft steel or piece of iron which is readily magnetized but
retains only a very small field after the active power of the external magnet
field is removed.
- Tensile
- Pertaining to forces on a body that tend to stretch, or elongate, the body.
A rope or wire under load is subject to tensile forces.
- Tensile
Strength - In tensile testing, the ratio of maximum load to the original
cross-sectional area.
- Tenth
Value Layer - That thickness of any material which will reduce radiation
intensity by a factor of 10.
- Test
Coil - Coil coupled to test material. It senses geometric, electric
and magnetic changes in test material.
- Test
Frequency
- The frequency f vibration of the ultrasonic transducer employed for ultrasonic
testing.
- Test
Surface - That surface of the test object at which the ultrasonic
energy enters or leaves.
- Thermal
Cycles - Repetitive changes in temperature, that is, from a low temperature
to a high temperature, and back again.
- Thompson-Gray
Model - A model that allows the approximate prediction
of ultrasonic scattering measurements made through liquid-solid interfaces.
- Thomson Scattering
(R) - When an x-ray photon interacts with the whole
atom so that the photon is scattered with no change in internal energy to
the scattering atom, nor to the x-ray photon.
- Three
Phase Alternating Current - commercial electricity is commonly transmitted
as three single-phase currents, that is, these separate currents following
separate sine curves, each at 60 cycles (or other frequency) per second, but
with the peaks of their individual curves one-third of a cycle apart. At least
three (sometimes four) conductors are required for three phase alternating
current.
- Threshold
- In reference to current or magnetic fields, the minimum strength necessary
to create a looked-for effect is called the threshold value. For example,
the minimum current necessary to produce a readable indication of a given
defect is the threshold value of current for the purpose.
- Threshold
Dose - The minimum dose that will produce a detectable degree of
any given effect.
- Through
Hardening - Hardening of a metal part, usually steel, in which the
hardness across a section of the part is essentially uniform; that is, the
center of the section is only slightly lower in hardness than the surface.
- Through-Transmission
- A test method in which ultrasonic energy is transmitted through the test
object and received by a second transducer on the opposite side. Changes in
received signal amplitude are taken as indications of variations in material
continuity.
- 3-2T
Radiography
- Quality level of radiography in which the finished radiograph displays a
discernible image of a penetrameter hole that has a diameter equal to twice
the penetrameter thickness. The penetrameter thickness equals 3 percent of
the material thickness.
- Thulium
170
- A radioisotope of the element thulium.
- Time
Base - See sweep.
- Time
Delay - See sweep delay.
- Time
of Flight
- The time for an acoustic wave to travel between two points, Fro example,
the time required for a pulse to travel from the transmitter to the receiver
via diffraction at a discontinuity edge or along the surface of the test object.
- Time Response
- A means for describing radio frequency (RF) response
of the waveform.
- Toe
Crack - a base-metal crack at the toe of the weld.
- Toe
of Weld - the junction between the face of a weld and the base metal.
- Tolerance
Dose - For industrial safety guidelines. 100 mr/week. (The word "tolerance"
should not be understood to have the meaning "allowable," e.g. tolerance
on machined parts.)
- Tone -
The
distinctive property of a complex sound.
- Tone
Burst
- A wave train consisting of several cycles of the same frequency.
- Torque
- A measure of the twisting moment applied to a part under a torsional stress.
Usually expressed in terms of inch pounds or foot pounds, although the terms
“pound inches” and “pound feet” are technically more
accurate for torsional moments.
- Torsion
- A twisting action applied to a generally shaft-like, cylindrical, or tubular
member. The twisting may be either reversed (back and forth) or unidirectional
(one way).
- Toughness
- Ability of a material to absorb, energy and deform plastically before fracturing.
Toughness is proportional to the area under the stress-strain curve from the
origin to the breaking point. In metals, toughness is usually measured by
the energy absorbed in a notch impact test.
- Tracers -
A radioactive element whose pathway through which a chemical reaction can
be followed.
- 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.
- Transmission
Angle - The incident angle of a transmitted ultrasonic beam. It is
zero degrees when the beam is perpendicular (normal) to the test surface.
- Transmission
Characteristics
- Test object characteristics that influence the passage of ultrasonic energy,
including scattering, attenuation or surface conditions.
- Transmission
Technique - See through-transmission.
- Transmitter
- The transducer that emits ultrasonic energy.
- The electrical circuits that generate the signals emitted by the transducer.
- Transmutation
- The
change of one element into another as a result of changes within the nucleus.
- Transverse
- Literally “across,” usually signifying a direction or plane
perpendicular to the axis of a part.
- Tritium
- A radioactive isotope of hydrogen with two neutrons and one proton in the
nucleus. It is heavier than deuterium (heavy hydrogen). Tritium is used in
industrial thickness gages, as a label in tracer experiments and in controlled
fusion experiments.
- Tungsten
- A metal commonly used to make the plugs used for
connecting metal wires to one another or to the devices in integrated circuits.
- Two-crystal
Method - Use of 2 crystals for sending and receiving. May be pulse-echo
or through transmission method.
- Two-Film
Technique
- A procedure wherein two films of different relative speeds are used simultaneously
to radiograph both the thick and the thin sections of an item.
- 2.2
T Radiography
- Quality level of radiography displays a discernible image of a penetrameter
hole that has a diameter equal to twice the penetrameter thickness. The penetramenter
thickness equals 2 percent of the material thickness.
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