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Dictionary – R

 

RADIANT TUBE ANNEALING BOX

(See Annealing) – A box which is heated, inside, by means of tubes on 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.


RECIPROCAL LATTICE

(For a crystal) – A group of points arranged about a center in such a way that the line joining each point to 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

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.


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 for vanity cases, coins, plaques, badges, etc. It is somewhat stronger than commercial bronze and is hardened more rapidly by cold working.


RED SHORTNESS

Brittleness in steel when it is red hot.


REDUCTION OF AREA

The percent of cross-sectional area the metal will “Neck Down” prior to breaking in tension.

% R.A. = Original area – Area after Fracture x 100


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.


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 STRESS

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.


RESIDUALS

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


RESILIENCE

The tendency of welding process in which the work pieces are heated by the passage of an electric current through the contact. Such processes include spot weldingseam or line welding and percussion welding. Flash and butt welding are sometimes considered as resistance welding processes.


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 weldingseam or line welding and percussion welding. Flash and butt welding are sometimes considered as resistance welding processes.


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 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.


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 metals. 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, give “scales” designated by letters varying from “A” to “H”; the “B” and “C” scales are most commonly in use.


ROENTGEN RAYS

(See X-rays)


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 buckleswavy edges, corrugations, twists, etc., or from steel in the higher hardness ranges.


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 tie contours of which determine or fashion the product into numerous intermediate and final shapes, e.g., bloomsslabs, 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 circles from flat sheets but with differently designed machines.


RULE DIE STEEL

hardened and tempered medium high carbon spring steel strip sufficiently low 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.