Radiography - A nondestructive method of internal examination in which metal or other objects are exposed to a beam of xray or gamma radiation. Differences in thickness, density or absorption, caused by internal discontinuities, are apparent in the shadow image either on a fluorescent screen or on photographic film placed behind the object.
Random Lengths - A term indicating no specified minimum or maximum length with lengths falling within the range indicated.
Red Shortness - See "Hot Shortness".
Reduction of Area - The difference between the original cross-sectional area of a tensile specimen and that of the smallest area at the point of rupture. It is usually stated as a percentage of the original area; also called the "contraction of area."
Regenerative Quenching - Quenching carburized parts from two different temperatures to refine case and core. (Often called double quenching.)
Rimmed Steel - A steel that is poured containing enough oxygen to evolve appreciable gas during solidification. The gas evolution results in a finished product having a very pure surface with the impurities concentrated in the interior. The pure zone which is readily shown by etching is referred to as the "rim".
Rockwell Hardness Test - Forcing a cone-shaped diamond or hardened steel ball into the specimen being tested under standard pressure. The depth of penetration is an indication of the Rockwell Hardness.
Roll Threading - Threading a bolt or screw by rolling it between two grooved die plates, one of which is in motion, or between rotating grooved circular rolls.
Rolled Edge - The edge on a universal plate when rolled by both vertical and horizontal rolls. Edge shearing is not necessary.
Roller Leveler - A rolling device used for eliminating buckles and waves in steel sheets and strip and for producing sheets of commercial flatness. The roller leveler has sets of rolls that are staggered to flex the sheet as it passes between them. Besides its use in levelling, it has extensive application for minimizing or temporarily eliminating the tendency to develop stretcher stains.