Radiant Tube Annealing Box
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. - (See Annealing)

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.

(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.

(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.

(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 Temperature
The approximate minimum temperature at which complete re-crystallization of a cold worked metal occurs within a specified time.

Re-crystallization 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 Shortness
Brittleness in steel when it is red hot.

Reducing Agent
Either natural gas or coal can be used to remove the oxygen from iron ore in order to produce a scrap substitute. In gas-based processes, the iron ore is heated in a vessel as reformed natural gas passes through. In coal-based processes, iron ore is combined with gasified or ground coal and heated. The oxygen in the ore combines with carbon and hydrogen in the gas or coal, producing reduced, or metallic, iron.

Reduction of Area

  • 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.
  • The difference, expressed as a percentage of original area, between original cross-sectional area and that after straining the specimen.

A processing plant usually associated with a smelter that produces high purity metal.

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.
Reflectivity (Reflectance)
A term to indicate the percentage of reflected light from a painted surface. Considered a function of color rather than specular gloss. Reflectance percentages usually range from 80% to 90% for white colors to 5% to 15% for dark colors. Reflectivity standards vary for each industry and specific application.

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 Brick
Heat-resistant brick. Because its melting point is well above the operating temperatures of the process, refractory bricks line most steelmaking vessels that come in contact with molten metal, like the walls of the blast furnace, sides of the ladles, and inside of the BOF.

Registry Printing
Printing successive colors or figures in a precise pattern and with exact superposition.

Reinforcing Bar (Rebar)
A commodity-grade steel used to strengthen concrete in highway and building construction.

The process of replacing the refractory lining of a liquid steel vessel. Once it wears out, the brick lining of a furnace must be cooled, stripped and replaced. This maintenance can be significant because a blast furnace reline may require up to three months to complete.

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
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.
Stress remaining in a metal part or structure as a result of welding.

The impurities in mini-mill steel as the result of the mix of metals entering the process dissolved in obsolete scrap. Residuals are key concerns regarding the mini-mills' recent entry into the flat-rolled market, where high residuals can leave sheet steel too brittle for customer use.

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.

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.

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

Reverse bend test
A bend test in which the other than that specified for a face bend test is in tension.

Reversing Mill
The stand of rolls used to reduce steel sheet or plate by passing the steel back and forth between the rolls; the gap between the rolls is reduced after each pass.

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

Waviness at the edge of sheet or strip.

Rightward welding
A gas welding technique in which the flame is (Backward welding)

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.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.

The circle of seats on the LME floor which brokers occupy when trading. More commonly the term is used to describe the periods of trading which are broken down in to 5 minute sessions for each metal.>/p> 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, five scales designated by letters varying from A to H; the B and C scales are most commonly in use.

Round, thin semi-finished steel length that is rolled from a billet and coiled for further processing. Rod is commonly drawn into wire products or used to make bolts and nails. Rod trains (rolling facilities) can run as fast as 20,000 feet per minute, more than 200 miles an hour.

Roentgen Rays
(See X-rays)

Roll Force Systems
Mill stands place considerable pressure on slabs, blooms and coils to further process the material. There are two general ways of applying the force to the steel, screw and hydraulic systems.

Root (of weld)
The zone on the side of the first run farthest from the welder.

Root face
The portion of a fusion face at the root which is not beveled or grooved.

Screw (Incline Plane)
This older method used the basic principle of the screw to adjust the space between the mill rolls. Because metal touches metal, these configurations will wear down over time and can cause quality problems.

Hydraulic (Pancake Cylinder)
This modern system uses fluid pressure to rapidly adjust the roll spacing several times per second. These minute, instantaneous adjustments allow for superior gauge tracking and higher-quality products.

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

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

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., 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 circles from flat sheets but with differently designed machines.

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.

A piece, or pieces, of metal so placed as to enable the full section of   weld to be obtained at the end of the joint.