ALCLAD ALUMINUM: A term applied to aluminum alloy sheet and wire products to which a thin coating of high
purity aluminum or aluminum alloy of different composition has been bonded for corrosion protection.
ALLOY: A metal composed of two or more chemical elements at least one of which is a metal.
ALLOY STEEL: Steel that has had sufficient quantities of alloying elements added to produce desired changes in the
mechanical or physical properties.
ALLOY SYSTEM: A complete series of compositions produced by mixing in all proportions any group of two or more
components, at least one of which is a metal.
ALLOYING ELEMENT: An element added to a metal to create a desired change in its properties.
ALPHA PARTICLE (RT): A positively charged particle emitted by certain radioactive materials. It is made up of two
neutrons and two protons; hence it is identical with the nucleus of a helium atom.
ALPHA RAY (RT): A stream of fast moving helium nuclei. This is a strongly ionizing radiation with very weak
ALPHA ROCKWELL HARDNESS: The index of the resistance of a plastic to surface penetration by a specified
indentor under a specified load applied with a tester. Higher values indicate higher resistance to indentation (ASTMD-
ALTERNATING CURRENT (AC): Alternating current is current that reverses its direction of flow at regular intervals.
Such current is frequently referred to as AC
ALUMINUM EQUIVALENT (RT, UT): The thickness of aluminum having a specified purity, affording the same
attenuation, under specified conditions, as the material in question.
AMPERAGE: The strength of a current of electricity measured in amperes.
AMPERE: This is the unit of electrical current. One ampere is the current that flows through a conductor having a
resistance of one ohm, at a potential of one volt.
AMPERE TURNS (MT): This term refers to the product of the number of turns in a coil and the number of amperes of
current flowing through it. This is a measure of the magnetizing or demagnetizing strength of the coil. For example:
800 amperes in a 6 turn coil = 800 x 6 = 4800 ampere turns.
AMPLIFIERS: Circuit components that increase the magnitude of an electronic signal.
AMPLITUDE: The extent of vibratory movement measured from the mean position to an extreme; the maximum
departure of alternating voltage or current from the average value; indicated by vertical height on an A-scan
AMPLITUDE ECHO (UT): The total vertical or pulse height of the received signal indicated by A scan presentation.
AMPLITUDE RESPONSE: That property of the test system whereby the amplitude of the detected signal is measured
without regard to phase.
AMU: Atomic mass unit.
ANGLE BEAM (UT): A sound beam traveling at some angle other than normal to me surface of the test object.
Measured from normal incidence.