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R

Radiant Tube Annealing Box
A box which is heated, inside, by means of tubes in which gas is burned; the hot tubes radiate their heat to the covered pile of metal, standing on the base of the box. Usually a protective atmosphere is maintained in the box to protect the metal from oxidation.

Radiography
A nondestructive method of internal examination in which metal objects are exposed to a beam of X-ray or gamma radiation. Differences in thickness, density or absorption, caused by internal defects or inclusions, are apparent in the shadow image either on a fluorescent screen or on photographic film placed behind the object.

Ragged Edges
Edges of Sheet or Strip which are torn, split, cracked, ragged or burred or otherwise disfigured.

Recarburizing
(1) Increasing the carbon content of molten cast iron or steel by adding carbonaceous material, high-carbon pig iron or a high-carbon alloy. (2) Carburizing a metal part to return surface carbon lost in processing.

Reciprocal Lattice (for a crystal)
A group of points arranged about a center in such a way that the line joining each point of the center is perpendicular to a family of planes in the crystal, and the length of this line is inversely proportional to their interplanar distance.

Recovery
Reduction or removal of work-hardening effects, without motion of large-angle grain boundaries.

(2) The removal of residual stresses by localized plastic flow as the result of low-temperature annealing operations; performed on cold worked metals without altering the grain structure or strength properties substantially.

Recrystallization
A process whereby a distorted grain structure of cold worked metals is replaced by a new, stress-free grain structure as a result of annealing above a specific minimum temperature for a specific time.

(2) The change from one crystal structure to another, as occurs on heating or cooling through a critical temperature.

(3) The formation of a new, strain-free grain structure from that existing in cold worked metal, usually accomplished by heating.

(4) A change from one crystal structure to another, such as that occurring on heating or cooling through a critical temperature.

(5) Formation of a new, strain-free grain, structure from the structure existing in cold worked metal.

Recrystallization Temperature
The approximate minimum temperature at which complete recrystallization of a cold worked metal occurs within a specified time.

(2) The approximate minimum temperature at which complete recrystallization of a cold worked metal occurs within a specified time.

Recystallization Annealing
Annealing cold worked metal to produce a new grain structure without a phase change.

Red Brass
85% Copper -- A copper-zinc alloy containing approximately 15% zinc, used for plumbing pipe, hardware, condenser tubes. Because of its color, is used or vanity cases, coins, plaques, badges, etc. It is somewhat stronger than commercial bronze and is hardened more rapidly by cold working.

Red Shorness
Brittleness in steel when it is red hot.

Reduction of Area
(1) Commonly, the difference, expressed as a percentage of original area, between the original cross-sectional area of a tensile test specimen and the minimum cross-sectional area measured after complete separation. (2) The difference, expressed as a percentage of original area, between original cross-sectional area and that after straining the specimen.

Refining Temperature
A temperature, usually just higher than the transformation range, employed in the heat treatment of steel to refine the structure -- in particular, the grain size.

Reflector Sheet
An alclad product containing on one side a surface layer of high-purity aluminum superimposed on a core or base alloy of commercial-purity aluminum or an aluminum-manganese alloy. The high-purity coating imparts good polishing characteristics and the core gives adequate strength and formability.

Refractory
A heat-resistant material, usually nonmetallic, which is used for furnace linings and such.

Refractory Alloy
A term applied to those alloys which due to hardness or abrasiveness present relative difficulty in maintaining close dimensional tolerances.

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.

Rephosphorizing (Steel)
A Ladle-chemical treatment consisting of the addition of phosphorus as a work hardening agent when temper rolling black plate or sheet steel resulting in greater hardness and stiffness and with a corresponding loss in ductility. . NOTE: Black Plate in tempers T5 and T6 (R/B range 68/84) are temper rolled from Rephosphorized steel.

Residual Elements
Small quantities of elements unintentionally present in an alloy.

Residual Stress
Stress present in a body that is free of external forces or thermal gradients.

(2) Macroscopic stresses that are set up within a metal as the result of non-uniform plastic deformation. This deformation may be caused by cold working or by drastic gradients of temperature from quenching or welding.

(3) Stress present in a body that is free of external forces or thermal gradients.

Residuals
'Incidental' or 'tramp' elements not named in a specification. These inclusions are usually due to contaminated scrap.

Resilience
The tendency of a material to return to its original shape after the removal of a stress that has produced elastic strain.

Resistance Welding
A type of welding process in which the work pieces are heated by the passage of an electric current through the contact. Such processes include spot welding, seam or line welding and percussion welding. Flash and butt welding are sometimes considered as resistance welding processes.

(2) Welding with electrical resistance heating and pressure, the work being part of an electrical circuit.

Resolution
The capacity of an optical or radiation system to separate closely spaced forms or entities; also, the degree to which such forms or entities can be discriminated.

Resulfurized Steel
Steel to which sulfur has been added in controlled amounts after refining. The sulfur is added to improve machinability.

Ribbon Wound
A term applied to a common method of winding strip steel layer upon layer around an arbor or mandrel.

Riffles
Waviness at the edge of sheet or strip.

Rimmed Steel
Low-carbon steel containing sufficient iron oxide to produce continuous evolution of carbon monoxide during ingot solidification, resulting in a case or rim of metal virtually free of voids.

(2) Low-carbon steel in which incomplete deoxidation permits the metal to remain liquid at the top of the ingot, resulting in the formation of a bottom and side rim of considerable thickness. The rim is of somewhat purer composition than the original metal poured. If the rimming action is stopped shortly after pouring of the ingot is completed, the metal is known as capped steel. Most steels below 0.15% carbon are rimmed steels. For the same carbon and manganese content rimmed steel is softer than killed steel.

(3) A low-carbon steel containing sufficient iron oxide to give a continuous evolution of carbon monoxide while the ingot is solidifying, resulting in a case or rim of metal virtually free of voids. Sheet and strip products made from the ingot have very good surface quality.

Ripple (defect)
A slight transverse wave or shadow mark appearing at intervals along the piece.

Rockwell Hardness (Test)
A standard method for measuring the hardness of metels. The hardness is expressed as a number related to the depth of residual penetration of a steel ball or diamond cone (brale) after a minor load of 10 kilograms has been applied to hold the penetrator in position. This residual penetration is automatically registered on a dial when the major load is removed from the penetrator. Various dial readings combined with different major loads, five scales designated by letters varying from A to H; the B and C scales are most commonly in use.

Roll Forming
An operation used in forming sheet. Strips of sheet are passed between rolls of definite settings that bend the sheet progressively into structural members of various contours, sometimes called molded sections.

Rolled Edges
Finished edges, the final contours of which are produced by side or edging rolls. The edge contours most commonly used are square corners, rounded corners and rounded edge.

Rolled In Scale
A surface defect consisting of scale partially rolled into the surface of the sheet.

Roller Leveling
Passing sheet or strip metal through a series of staggered small rolls so as to flatten the metal. This method is relatively ineffective in removing defects such as buckles, wavy edges, corrugations, twists, etc., or from steel in the higher hardness ranges.

(2) Leveling by passing flat stock through a machine having a series of small-diameter staggered rolls.

Rolling
Reducing the cross-sectional area of metal stock, or otherwise shaping metal products, through the use of rotating rolls.

Rolling
A term applied to the operation of shaping and reducing metal in thickness by passing it between rolls which compress, shape and lengthen it following the roll pattern.

Rolling Direction (in rolled metal)
The direction, in the plane of the sheet, perpendicular to the axes of the rolls during rolling.

Rolling Mills
Equipment used for rolling down metal to a smaller size or to a given shape employing sets of rolls the contours of which determine or fashion the product into numerous intermediate and final shapes, e.g., blooms, slabs, rails, bars, rods, sections, plates, sheets and strip.

Rotary Shear (Slitting Machine)
A cutting machine with sharpened circular blades or disc-like cutters used for trimming edges and slitting sheet and foil. NOTE: cutter discs are also employed in producing dircles from flat sheets but with differently designed machines.

Rough Machining
Machining without regard to finish, usually to be followed by a subsequent operation.

Rule Die Steel
A hardened and tempered medium high carbon spring steel strip sufficiently low in hardness to take moderately sharp bends without fracture, intended for manufacture into rule dies for the purpose of cutting or stamping fabrics, paper, cardboard, plastics, and metal foil into desired shape.