Camber

(1) Edgewise curvature deviation from edge straightness usually referring to the greatest deviation of side edge from a straight line. (2) Sometimes used to denote crown in rolls where the center diameter has been increased to compensate for deflection cause by the rolling pressure.

Canning

A dished distortion in a flat or nearly flat surface, sometimes referred to as oil canning.

Casting

(1) An object at or near finished shape obtained by solidification of a substance in a mold. (2) Pouring molten metal into a mold to produce an object of desired shape.

Caustic Etch

Like the bright dip, caustic etch is a pretreatment for anodizing. The anodic film is transparent and exposes the as-received surface of the aluminum which may not be pleasing to the eye. By subjecting the bare, clean aluminum to a caustic bath, the surface of the metal will be minutely eaten away and leveled. The resulting soft frosted, or matte, appearance is consistently attractive under the anodic film.

Caustic Stain

A superficial surface blemish caused by the etching action of caustic.

Center

The difference in thickness between the middle and edges of a sheet. (This is also known as crown.)

Center Buckle

Undulation (wavy region) in the center of the metal.

Chamfer

(1) A beveled surface to eliminate an otherwise sharp corner. (2) A relieved angular cutting edge at a tooth corner.

Charpy Test

A pendulum-type single-blow impact test in which the specimen usually notched, is supported at both ends as a simple beam and broken by a falling pendulum. The energy absorbed, as determined by the subsequent rise of the pendulum, is a measure of impact strength or notch toughness.

Chatter Marks

Parallel indentations or marks appearing at right angles to edge of strip forming a pattern at close and regular intervals, caused by roll vibrations.

Chemical Milling

Removing metal stock by controlled selective chemical etching.

Chemical Polishing

Improving the specular reflectivity of a metal surface by chemical treatment.

Chemical Properties

The properties of a material that describe its reactions with other substances, e.g., corrosion resistance.

Chromadizing (Chromodizing, Chromatizing)

Forming an acid surface to improve paint adhesion on aluminum or aluminum alloys, mainly aircraft skins, by treatment with a solution of chromic acid.

Circle

A circular blank fabricated from plate, sheet or foil.

Clad Metal

A composite metal containing two or three layers that have been bonded together. The bonding may have been accomplished by co-rolling, welding, heavy chemical deposition or heavy electroplating.

Clad Sheet

Composite sheet having on both surfaces (If on one side only, Clad One Side Sheet) a metallurgically bonded coating, the composition of which may or may not be the same as that of the core.

Cladding

A process for covering one metal with another. Usually the surfaces of fairly thick slabs of two metals are brought carefully into contact and are then subjected to co-rolling so that a clad composition results. In some instances a thick electroplate may be deposited before rolling.

Cleavage

Fracture of a crystal by crack propagation across a crystallographic plane of low index.

Cleavage Fracture

Fracture of a grain, or most of the grains, in a polycrystalline metal by cleavage, resulting in bright reflecting facets.

Cleavage Plane

A characteristic crystallographic plane or set of planes in a crystal on which cleavage fracture occurs easily.

Close Tolerance

A tolerance closer than "Standard".

Coating

Lacquer-type or wax films applied to one or both surfaces of foil for such purpose as heat-sealing, primer coat base for printing, or as protection against chemical attack.

Coating Blister

A blister in the coating of an alclad or a clad product.

Coating Build-Up

A coating thickness greater than nominal in localized area of sheet, usually along edges, due to uneven application techniques.

Coating Drip

A non-uniform extraneous deposit of coating on the coated sheet.

Coating Streak

A surface blemish on rolled material resulting from aluminum oxide transferring from the roll to the sheet surface, giving a speckled appearance; known also as ""roll-coating pickup""

Coating, Conversion

An inorganic pretreatment sometimes applied to metal surface to enhance coating adhesion and to retard corrosion.

Coating, High or Low

Failure of the coating to meet the agreed upon thickness limits measured in weight per unit area.

Cobble

(1) A jamming of the mill by aluminum product while being rolled. (2) A piece of aluminum which for any reason has become so bent or twisted that it must be withdrawn from the rolling operation and scrapped.

Coil Breaks

Creases or ridges across a metal sheet transverse to the direction of coiling, occasionally occurring when the metal has been coiled hot and uncoiled cold.

Coil Curvature

("Coil Set") Longitudinal bow in an unwound coil in the same direction as curvature of the wound coil.

Coil Orientation

Clockwise Coil: With the coil core vertical ("eye to the sky") and viewed from above, a trace of the metal edge from the ID to the OD involves clockwise movement. Counter-Clockwise (Anti-Clockwise) Coil: With the coil core vertical ("eye to the sky") and viewed from above, a trace of the metal edge from the ID to the OD involves a counter-clockwise (anti-clockwise) movement.

Coil Set or Longitudinal Curl

A lengthwise curve or set found in coiled strip metals following its coil pattern. A departure from longitudinal flatness. Can be removed by roller or stretcher leveling from metals in the softer temper ranges.

Coil Set Differential

The difference in coil set from edge to edge of a coiled sheet sample. It is measured with the sample on a flat table, concave side up, and is the difference in elevation of the corners on one end.

Coil Set, Reversed

Longitudinal bow in an unwound coil in the direction opposite to the curvature of the wound coil.

Coil Weld

A joint between two lengths of metal within a coil - not always visible in the cold reduced product.

Coiled Sheet

Sheet in coils with slit edges.

Coiled Sheet Circles

Circles cut from coiled sheet.

Coils

Coiled flat sheet or strip metal- usually in one continuous piece or length.

Coining

A process of impressing images or characters of the die and punch onto a plane metal surface.

Cold Reduced Strip

Metal strip, produced from hot-rolled strip, by rolling on a cold reduction mill.

Cold Reduction

Reduction of metal size, usually by rolling or drawing particularly thickness, while the metal is maintained at room temperature or below the recrystallization temperature of the metal.

Cold Rolling

Rolling metal at a temperature below the softening point of the metal to create strain hardening (work-hardening). Same as cold reduction, except that the working method is limited to rolling. Cold rolling changes the mechanical properties of strip and produces certain useful combinations of hardness, strength, stiffness, ductility and other characteristics known as tempers, which see.

Cold Work

Permanent strain produced by an external force in a metal below its recrystallization temperature.

Cold Working

Plastic deformation, such as rolling, hammering, drawing, etc., at a temperature sufficiently low to create strain-hardening (work-hardening). Commonly, the term refers to such deformation at normal temperatures.

Columnar Structure

(1)A structure consisting of elongated grains whose long axes are parallel. (2) A coarse structure of parallel columns of grains, having the long axis perpendicular to the casting surface.

Commercial Tolerance

A term sometimes used synonymously with "Standard Tolerance". The term "Standard Tolerance" is preferred.

Common Alloys

One of several terms used in the industry to identify the non-heat-treatable classes of alloys—alloys identified in the four-digit numbering system by having as their first digit a "1", a "3", a "5", or in some cases an "8". This category of alloys has its strength levels increased by being subjected to some type of cold-working processes such as rolling, drawing, or stretching, but not through any of the thermal processes. Exposure to temperatures above rather low levels can only reduce the strength of the non-heat-treatable or common alloys.

Compressive Strength

The maximum compressive stress that a material is capable of developing, based on original area of cross section. In the case of a material which fails in compression by a shattering fracture, the compressive strength has a very definite value. In the case of materials which do not fail in compression by a shattering fracture, the value obtained for compressive strength is an arbitrary value depending upon the degree of distortion that is regarded as indicating complete failure of the material.

Concentricity

Conformance to a common center as, for example, the inner and outer walls of round tube.

Condensation Stain

Corrosion, Water Stain: Superficial oxidation of the surface with a water film, in the absence of circulating air, held between closely adjacent metal surfaces.

Coned-out Coil

Telescoping: Lateral stacking, primarily in one direction, of wraps in a coil so that the edges of the coil are conical rather than flat. Improper alignment of rolls over which the metal passes before rewinding is a typical cause. See also "Oscillation."

Constitutant

A phase, or combination of phases, that occurs in a characteristic configuration in a microstructure.

Constitutional Diagram

A graphical representation of the temperature and composition limits of phase fields in an alloy system as they actually exist under specific conditions of heating and cooling (synonymous with phase diagram). A constitutional diagram may be, or may approximate, and equilibrium diagram, or may represent metastable conditions or phases. Compare equilibrium diagram.

Continuous Casting

Continuous Furnace

Furnace, in which the material being heated moves steadily through the furnace.

Continuous Phase

In an alloy or portion of an alloy containing more than one phase, the phase that forms the background or matrix in which the other phase or phases are present as isolated volumes.

Continuous Strip Mill

A series of synchronized rolling mill stands in which coiled flat rolled metal entering the first pass (or stand) moves in a straight line and is continuously reduced in thickness (not width) at each subsequent pass. The finished strip is recoiled upon leaving the final or finishing pass.

Controlled Atmosphere Furnaces

A furnace used for bright annealing into which specially prepared gases are introduced for the purpose of maintaining a neutral atmosphere so that no oxidizing reaction between metal and atmosphere takes place.

Conversion Coatings

(See Alodizing) Proprietary solutions, usually of a chromate or a phosphate variety, which when applied to a clean aluminum surface will serve to increase the metal’s resistance to corrosion and provide a good base for paint adhesion. In addition, some manufactures use conversion coatings to enhance the aesthetics of their products.

Convexity

Curved like the outer surface of a sphere. See also "Concavity."

Cooling Stresses

Stresses developed by uneven contraction or external constraint of metal during cooling; also those stresses resulting from localized plastic deformation during cooling, and retained.

Core

A hollow cylinder on which a coiled product may be wound that forms the inside diameter of a coil.

Core Blister

A blister in the core of an alclad or a clad product.

Coring

A variation of composition between the center and surface of a unit of structure (such as a dendrite, a grain or a carbide particle) resulting from non-equilibrium growth over a range of temperature.

Corner Turn-up

A distortion, buckle or twist condition that causes the corner(s) of the sheet to deviate from a perfectly flat plane on which it rests.

Corrosion

(1)Gradual chemical or electrochemical attack on a metal by atmosphere, moisture or other agents.(2) Deterioration of a metal by chemical or electrochemical reaction with its environment. (3) The deterioration of a material due to its reaction to its environment. Depending upon the type of corrosive conditions, the deterioration may be staining, pitting, flaking or, in very severe cases, fracturing—particularly if the metal is under stress.

Corrosion Embrittlement

(1)The severe loss of ductility of a metal resulting from corrosive attack, usually intergranular and often not visually apparent. (2) The embrittlement caused in certain alloys by exposure to a corrosive environment. Such material is usually susceptible to the intergranular type of corrosion attack.

Corrosion, Exfoliation

Corrosion that progresses approximately parallel to the metal surface, causing layers of the metal to be elevated by the formation of corrosion product.

Corrosion Fatigue

Effect of the application of repeated or fluctuating stresses in a corrosive environment characterized by shorter life than would be encountered as a result of either their repeated or fluctuating stresses alone or the corrosive environment alone.

Corrosion, Galvanic

Corrosion associated with the current of galvanic cell consisting of two dissimilar conductors in an electrolyte or two similar conductors in dissimilar electrolytes. Aluminum will corrode if it is anodic to the dissimilar metal.

Corrosion, Intergranular

Corrosion occurring preferentially at grain boundaries. (Also termed intercrystalline corrosion).

Corrosion, Pitting

Localized corrosion resulting in small pits or craters in a metal surface.

Corrosion, Stress Cracking

Failure by cracking resulting from selective directional attack caused by the simultaneous inter-action of sustained tensile stress at an exposed surface with the chemical or electrochemical effects of the service environment.

Corrosion, Water Stain

Superficial oxidation of the surface with a water film, in the absence of circulating air, held between closely adjacent metal surfaces.

Corrugated

As a defect. Alternate ridges and furrows. A series of deep short waves.

Corrugating

Forming rolled metal into a series of straight parallel regular alternate grooves and ridges.

Coupon

A piece of metal from which a test specimen may be prepared-usually produced as an integral extra piece as on a casting or forging or as a separately cast or forged piece.

Crazing

A macroscopic effect of numerous surface tears, transverse to the rolling direction, which can occur when the entry angle into the cold mill work rolls is large.

Crease

A sharp deviation from flat in the sheet which is transferred from processing equipment subsequent to the roll bite.

Creep

(1) Time-dependent strain occurring under stress. (2) The flow or plastic deformation of metals held for long periods of time at stresses lower than the normal yield strength. The effect is particularly important if the temperature of stressing is above the recrystallization temperature of the metal. (3) Time-dependent strain occurring under stress. The creep strain occurring at a diminishing rate is called primary creep; that occurring at a minimum and almost constant rate, secondary creep; that occurring at an accelerating rate, tertiary creep.

Creep Limit

(1) The maximum stress that will cause less than a specified quantity of creep in a given time. (2) The maximum nominal stress under which the creep strain rate decreases continuously with time under constant load and at constant temperature. Sometimes used synonymously with creep strength.

Creep Strength

(1) The constant nominal stress that will cause a specified quantity of creep in a given time at constant temperature. (2) The constant nominal stress that will cause a specified creep react at constant temperature.

Crevice Erosion

A type of concentration-cell corrosion; corrosion of a metal that is caused by the concentration of dissolved salts, metal ions, oxygen, or other gases, and such, in crevices or pockets remote from the principal fluid stream, with a resultant building up of differential cells that ultimately cause deep pitting.

Critical Point

(1) The temperature or pressure at which a change in crystal structure, phase or physical properties occurs; same as transformation temperature. (2) In an equilibrium diagram, that specific combination of composition, temperature and pressure at which the phases of an inhomogeneous system are in equilibrium.

Critical Strain

That strain which results in the formation of very large grains during recrystallization.

Critical Temperature

Synonymous with critical point if pressure is constant.

Crop

The defective ends of a rolled or forged product which are cut off and discarded.

Cross Direction (in rolled or drawn metal)

The direction parallel to the axes of the rolls during rolling. The direction at right angles to the direction of rolling or drawing.

Cross-Hatched Surface

A surface having innumerable minute cracks running normal to the direction of working.

Cross Rolling

Crown

A contour on a sheet or roll where the thickness or diameter increases from edge to center.

Crown or Heavy Center

Increased thickness in the center of metal sheet or strip as compared with thickness at the edge.

Crystal

(1) A physically homogeneous solid in which the atoms. ions or molecules are arranged in a three-dimensional repetitive pattern. (2) A coherent piece of matter, all parts of which have the same anisotropic arrangement of atom; in metals, usually synonymous with grain and crystallite.

Crystalline

Composed of crystals.

Crystalline Fracture

A fracture of a polycrystalline metal characterized by a grainy appearance. Compare fibrous fracture.

Crystallization

The formation of crystals by the atoms assuming definite positions in a crystal lattice. This is what happens when a liquid metal solidifies. (Fatigue, the failure of metals under repeated stresses, is sometimes falsely attributed to crystallization.)

Cube-Centered

Metallography- (concerning space lattices) - Body-centered cubic. Refers to crystal structure.

Cup Fracture (Cup-and-Cone Fracture)

Fracture, frequently seen in tensile test pieces of a ductile material, in which the surface of failure on one portion shows a central flat area of failure in tension, with an exterior extended rim of failure in shear.

Curl

An undesirable condition caused by uneven rates of absorption or evaporation of moisture, uneven rates of contraction or expansion, or internal stresses in the material. Curl is most prevalent in laminated structures where the components have differing physical properties.

Cutting Speed

The linear or peripheral speed of relative motion between the tool and work piece in the principal direction of cutting.