REFRACTORY METAL: A metal having an extremely high melting point. In the broad sense, it refers to metals
having melting points above the range of iron, cobalt and nickel.
REINFORCEMENT OF WELD:
In a butt joint, weld metal on the face of the weld that extends out beyond a surface plane common to the
members being welded.
In a fillet weld, weld metal that contributes to convexity.
In a flash, upset or gas pressure weld, the original diameter or thickness.
REJECT (SUPPRESSION) (UT): A control used for minimizing or eliminating low amplitude signals (electrical or
material noise) so that larger signals are emphasized. Use of this control can reduce the vertical linearity of the
REJECTION LEVEL (UT): The setting of the signal level above or below which all parts are rejectable as, in an
automatic system, at which objectionable parts will actuate the reject mechanism of the system.
RELATIVE BIOLOGICAL EFFECTIVENESS (RBE): The relative effectiveness of a given kind of ionizing radiation
in producing a biological response as compared with 250,000 electron volt gamma rays.
RELATIVE EXPOSURE: Exposure expressed relative to a standard exposure that is arbitrarily assigned the value of
RELATIVE SPEED (RT): The exposure time of any radiographic film relative to one particular type of film whose
speed is arbitrarily assigned the value of 100.
RELEVANT DISCONTINUITY: Discontinuity that is detrimental to the intended use of a part or material.
RELUCTANCE: The degree of difficulty with which the magnetic flux is produced within a material. Material of high
permeability has low reluctance.
REM: The special unit of any of the quantities expressed as dose equivalent. The dose equivalent in rems is equal to
absorbed dose in rads multiplied by the quality factor (1 rem = 0.01 sievert).
REMNANT MAGNETISM: This is the term applied to the magnetism remaining in a magnetic circuit after the
magnetizing force is removed.
REMOVER (PT): See PENETRANT REMOVER.
REP: Roentgen equivalent physical. An obsolete unit of radiation dosage now superseded by the rad.
REPETITION RATE (UT): The rate at which the individual pulses of acoustic energy are generated; also PULSE
REPLENISHER (RT): A modified form of the original developer which, when added to partially exhausted developer,
restores its efficiency.
RESIDUAL ELEMENTS: Elements present in an alloy in small quantities, but not added intentionally.
RESIDUAL FIELD (MT): See FIELD, RESIDUAL.
RESIDUAL MAGNETISM (MT): The magnetic field remaining in a part after the current has been removed.