ANGLE OF INCIDENCE (UT): The angle defined by the direction of propagation of refracted wave and the normal to
the interface at the point of incidence.
ANGLE OF REFLECTION (UT): The angle defined by the direction of propagation of refracted wave and the normal
to the interface at the point of incidence.
ANGLE TRANSDUCER (UT): A transducer used in angled testing in which the sound beam is set to some
predetermined angle to achieve a special effect, e.g., setting up shear or surface waves in the tested piece.
ANGSTROM (A): Unit of length usually reserved for the expression of wavelength. One Angstrom equals 10-8 cm.
Under the standard system of units, the Angstrom will be replaced by the nanometer (1.0 A = 0.10 nm). This is the
standard unit for measuring wavelengths of light.
ANNEAL: Heating metal to above its critical temperature range, then slowly cooling to remove stresses, induce
softness, remove gases, alter ductility, induce toughness, or modify electrical, magnetic or other physical properties.
ANODE (TARGET) (RT): The positive terminal of an X-ray tube. It is a high atomic number, high melting point
element, and receives the electron bombardment from the cathode or negative terminal.
ANODE CORROSION: The dissolution of a metal acting as an anode.
ANODE CURRENT (RT): See tube current.
ANODE STEM (RT): The metallic rod on which the target is mounted, and which is sealed to the envelope of the X-
ANODIZING: Forming a coating on a metal surface by anodic oxidation; most frequently on aluminum.
ANTINODE: Point in a standing wave where some characteristics of the wave field has a maximum amplitude.
ANTI-SCATTER GRID (RT): An array of X-ray opaque and transparent sections of materials placed between the
specimen and the film to minimize the effect of scattered radiation on the radiographic image, e.g., a Potter-Bucky
APPLICATION TIME (PT): The period of time wherein parts are immersed in a bath of liquid penetrant, plus the time
the liquid penetrant remains on the surface of the part, i.e., soak time and dwell time.
ARC STRIKE: A burned area where the weld or adjacent surface is marred by the slight addition or loss of metal
usually caused by inadvertent contact with the welding electrode.
AREA MONITORING (RT): The continued measurement of ionizing radiation exposure or dose levels in an area for
the purpose of radiation protection.
AREA OF INTEREST (RT): The specific portion of the specimen image on the radiograph that is to be evaluated.
ARTIFACT (RT): Film blemishes produced during the manufacture, packaging, handling, or processing of film which
are not associated with the actual condition of the material tested. They appear as white or black crescents, fogging,
A-SCAN (UT): A data presentation method by which intelligence signals from a signal object located are displayed.
As generally applied to pulse echo ultrasonics, the horizontal and vertical sweeps are proportional to time or distance
and amplitude or magnitude respectively. Thus the location and magnitude of acoustical interface are indicated as to
depth below the transducer.