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Heat Treatment Requirements
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.
Recovery
(1) 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.
Recrystallization
(1) The change from one crystal structure to another, as occurs on heating or
cooling through a critical temperature. (2) The formation of a new, strain-free
grain structure from that existing in cold worked metal, usually accomplished by
heating.
Recrystallization
(1) A change from one crystal structure to another, such as that occurring on
heating or cooling through a critical temperature. (2) 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.
Recrystallization Temperature
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.
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.
Residual Stress
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.
Resistance Welding
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.
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.
Rimmed Steel
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.
Roller Leveling
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.