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Glossary of Aluminum Coil Terminology

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    Abrasion
    Rubbing, grinding, or wearing away by friction.
    Aerospace Alloys
    Heat treatable alloys in the 2000 and 7000 series, including 2024 and 7075, are often used in aerospace applications and are sometimes referred to as aerospace alloys. Tighter gauge tolerances are given for this group of alloys in ANSI H35.2.
    Aging (called Ageing in UK)
    Precipitation from solid solution resulting in a change in properties of an alloy, usually occurring at room temperature (natural aging), or at elevated temperature (artificial aging).
    Alclad
    Composite sheet produced by bonding either corrosion-resistant aluminum alloy or aluminum of high purity to base metal of structurally stronger aluminum alloy. The coatings are anodic to the core so they protect exposed areas of the core electrolytically during exposure to corrosive environment.
    Alligatoring
    Also called lamination, an internal crack or separation parallel to the rolled surfaces. Typically a result of insufficient trim at hot rolling.
    Alloy
    A substance having metallic properties and composed of at least two or more elements of which at least one is an elemental metal. Aluminum alloys for sheet products are identified by a four digit numerical system which is administered by the Aluminum Association. See “Aluminum Alloy Designations” section of the Technical Manual.
    Alloy Selection
    See the “Selection Guide for Aluminum Alloys and Tempers” Table in the Technical Manual section.
    Alloying Element
    An element added to a metal, and remaining in solid solution in the metal, that effects changes in structure and properties.
    Aluminum – chemical symbol Al (called Aluminium in UK)
    Element No. 13 of the periodic system; Atomic weight 26.97; silvery white metal of valence 3; melting point 1220 (degrees) F; boiling point approximately 4118 (degrees) F.; ductile and malleable; stable against normal atmospheric corrosion. Aluminum is used extensively in articles requiring lightness, corrosion resistance, electrical conductivity, etc. See “Benefits of Aluminum” section in the Technical Manual.
    Aluminum Association
    The Aluminum Association, based in Washington, D.C., represents U.S. and foreign-based primary producers of aluminum, aluminum recyclers and producers of aluminum fabricated products. United Aluminum is a founder member of the Association.
    AMS
    Abbreviation for Aerospace Material Specification.
    Annealing
    Thermal treatment used to soften metal by removing stress created from cold working.
    Anodizing (called Anodising in UK)
    The process of coating aluminum by anodic treatment resulting in a thin film of aluminum oxide of extreme hardness. A wide variety of dye colored coatings are possible by impregnation in process.
    Anodizing Quality
    An indication that special attention has been paid to the metallurgical characteristics and surface quality of the aluminum sheet to assure that a uniform and blemish-free decorative anodic film will form during anodizing. United Aluminum can meet your anodizing quality needs.
    ANSI
    Abbreviation of American National Standards Institute. Dimensional tolerances for aluminum sheet and coil are covered by ANSI H35.2.
    ASME
    Abbreviation for American Society of Mechanical Engineers.
    ASTM
    Abbreviation for American Society For Testing Material. An organization for issuing standard specifications on materials, including metals and alloys. Most aluminum sheet produced by United Aluminum is covered by ASTM B209.
    AWS
    Abbreviation for American Welding Society.
    Bauxite
    Commercially mined ore of aluminum
    Belled Edge
    Excessive buildup of material on edge(s) of a coil during a rewinding operation. Typical causes include excessive edge burr, turned edge, and “dog bone” shaped cross sectional profiles.
    Bend Radius
    The inside radius of a bent section. See “Minimum Recommended Bend Radii” in Technical Manual.
    Bend Test
    Various tests which are used to ascertain the toughness and ductility of a metal product, in which the material is bent around its axis and/ or around an outside radius. A complete test might specify such a bend to be both with and against the direction of grain.
    Blank
    A piece of metal cut or formed to regular or irregular shape for subsequent processing by forming, bending or drawing. Typical Blanks include circles and square shapes.
    Blister
    A defect in metal, on or near the surface, resulting from the expansion of gas in a subsurface zone.
    Bow, Lateral
    See “Camber”.
    Bow, Longitudinal
    Curvature in the plane of sheet or coil in the rolling direction.
    Bow, Transverse
    Curvature across the rolling direction of sheet or coil.
    Brazing / Brazing Sheet
    Some aluminum sheet products are made up of a strong core alloy that is clad with a thin layer of a high-silicon alloy which has a much lower melting point than the core (see also “Clad Products”). This allows a complex shape, such as a car radiator, to be fabricated then heated to a temperature that is sufficient to melt the cladding while leaving the core intact. The thin skin of oxide film that covers the surface of aluminum needs to be removed for effective brazing. There are three common brazing methods:
    Flux-Dip Brazing
    The component is immersed in a molten salt which acts as a flux as well as a heat source for melting the clad layer. The fluxes
    are corrosive and all traces must be removed after brazing.
    Controlled Atmosphere Brazing (CAB)
    Sometimes also described by the trade name “Nocolok”, this process uses a non-corrosive powdered flux and an inert
    gas atmosphere.
    Vacuum Brazing
    Components are heated in a high vacuum, completely free of oxygen. The clad alloy must contain magnesium as an alloying
    addition. At the brazing temperature, the heat and vacuum causes the magnesium to “boil” out of the molten metal thereby breaking
    up the brittle oxide skin into small, harmless shards.
    See United Aluminum Capabilities data for information on Brazing Sheet offered
    Bright Dip (also called Chemical Brightening)
    An acid/copper solution into which pieces made from high-purity aluminum are dipped in order to obtain a clean, bright surface. The reaction is entirely chemical with no external source of electrical current. See also Electrobrightening.
    Brittleness
    The tendency of a metal or material to fracture without undergoing appreciable plastic deformation.
    Bruise
    A greatly enlarged roll mark whose height or depth is very shallow.
    Buckle
    A surface distortion of bulges and/ or hollows occurring along the length metal with otherwise flat edges.
    Buckle, Center
    Undulation (wavy region) in the center of the metal.
    Buckle, Edge
    Undulation (wavy region) along the edge(s) of the metal.
    Buckle, Quarter
    Undulation (wavy region) which occurs approximately at both quarter points across the width.
    Buffing
    A mechanical finishing operation in which fine abrasives are applied to a metal surface by rotating fabric wheels for the purpose of developing a lustrous finish.
    Buff Streak
    A dull continuous streak caused by smudge buildup on a buff used at shearing or other operations.
    Burr
    A thin ridge of roughness along the edge of slit or sheared coil or sheet.
    Butt Welding
    Joining two edges or ends by placing one against the other and welding them.
    Camber
    See also “Lateral Bow”: An edgewise curvature referring to the deviation of side edge from a straight line.
    See “Lateral Bow Limits” section of Technical Manual.
    Canning
    A dished distortion in a flat or nearly flat surface, sometimes referred to as oil canning.
    Chatter Marks
    Intermittent parallel indentations or marks appearing at right angles to edge of strip forming a pattern caused by roll vibrations.
    Chemical Brightening
    See Bright Dip and Electrobrightening
    Chemical Composition
    Composition in percent by weight according to the Aluminum Association. See “Chemical Composition Limits for Aluminum Alloys” Table in the Technical Manual
    Clad Products
    Metallurgicaly bonded composite sheet of differing core and surface alloys, 1 or 2 sides.
    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.
    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
    Also called Coil Curvature. 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, Reversed
    Longitudinal bow in an unwound coil in the direction opposite to the curvature of the wound coil.
    Coiled Sheet
    Sheet in coils with slit edges.
    Coils
    Coiled flat sheet or strip metal- usually one continuous piece or length.
    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.
    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.
    Commercial Tolerance
    A term sometimes used synonymously with “Standard Tolerance”. Typically refers to those tolerance limits published by the Aluminum Association. See “Aluminum Sheet & Coil Published Dimensional Tolerances” section of the Technical Manual
    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”. Strengthened by cold working rather than thermal processes.
    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. See also “Oscillation.”
    Continuous Casting
    A casting technique in which an ingot, billet, tube, or other shape is continuously solidified while it is being poured, so that its length is not determined by mold dimensions.
    Controlled Atmosphere Brazing (CAB)
    Sometimes also described by the trade name “Nocolok”, this process uses a non-corrosive powdered flux and an inert gas atmosphere. See United Aluminum Capabilities data for information on Brazing Sheet offered.
    Conversion Coatings
    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.
    Corrosion
    Deterioration of a metal by chemical or electrochemical reaction with its environment. Aluminum corrosion characteristics include general white staining (white rust) as well as pitting.
    Corrosion, Water Stain
    Superficial oxidation of the surface with a water film, in the absence of circulating air, held between closely adjacent metal surfaces. See “Water Stain and its Prevention” Section of the Technical Manual
    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.
    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.
    Cross Direction (in rolled or drawn metal)
    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.
    Crown
    A contour on a sheet or roll where the thickness or diameter increases from edge to center.
    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.
    Cut (also called Pad or Pancake Coil)
    Common term for a narrow-slit coil. See also Mult.
    Cutter Mark
    See Knife Mark
    DC (Direct Chill) Casting
    A continuous method of making ingots or billets for sheet or extrusion by pouring the metal into a short mold. The base of the mold is a platform that is gradually lowered while the metal solidifies, the frozen shell of metal acting as a retainer for the liquid metal below the wall of the mold. The ingot is usually cooled by the impingement of water directly on the mold or on the walls of the solid metal as it is lowered. The length of the ingot is limited by the depth to which the platform can be lowered; therefore, it is often called semi continuous casting.
    Deburring
    A method whereby the raw slit edge of metal is removed by rolling or filing.
    Deep Drawing
    Forming a deeply recessed part by forcing sheet metal to undergo plastic flow between dies. May require “deep draw” quality metal. See Capabilities
    Dent
    A sharply defined surface impression on the metal which may be caused by a blow from another object.
    Dent, Expansion
    Surface deviation from flat generated by expansion of vapor during thermal treatment of cold rolled coiled sheet.
    Dent, Repeating
    Repeating depression caused by a particle adhering to a rotating roll over which the metal has passed.
    Die-Lines
    Lines of markings caused on drawn or extruded products by minor imperfections in the surface of the die.
    Dish
    A concave surface departing from a straight line edge to edge. Indicates transverse or across the width.
    Drawing
    Forming recessed parts by forcing the plastic flow of metal in dies. See also Deep Drawing.
    Drawn-In Scratch
    A scratch occurring in the fabricating process and subsequently drawn over making it relatively smooth to the touch.
    Drawn Product
    A product formed by pulling material through a die.
    Ductility
    The ability of a material to deform plastically without fracturing, being measured by elongation or reduction of area in a tensile test, by height of cupping in an Erichsen test or by other means.
    Earing
    Wavy projections formed at the open end of a cup or shell in the course of deep drawing because of difference in directional properties. Also termed scallop. Also: Isotropy
    Ears
    Wavy symmetrical projections formed in the course of deep drawing or spinning as a result of directional properties or anisotropy in sheet. Ears occur in groups of 4 or 8 with the peaks of the projections located at 45 degrees and/or at 0 to 90 degrees to the rolling direction. Degree of earing is the difference between average height at the peaks and average height at the valleys, dividing by average height at the valleys, multiplied by 100 and expressed in percent.
    Edge, Belled
    Excessive buildup of material on edge(s) during a rewinding operation. Typical causes include excessive edge burr, turned edge, and “dog bone” shaped cross sectional profiles.
    Edge Ripple
    Undulation (wavy region) along the edge(s) of the metal. Also referred as Edge Buckle.
    Edge Strain or Edge Breaks
    Creases extending in from the edge of the temper rolled sheet.
    Elastic Limit
    Maximum stress that a material will stand before permanent deformation occurs. The maximum stress to which a material may be subjected without any permanent strain remaining upon complete release of stress.
    Elastic Strain
    Dimensional changes accompanying stress where the original dimensions are restored upon release of the stress.
    Electrical Conductivity
    The capacity of a material to conduct electric current. For aluminum, this capacity is expressed as a percentage of the International Annealed Copper Standard which as a resistivity of 1/58 ohm-mm2/metre at 20° C and an arbitrarily designed conductivity of unity. See “Typical Physical Properties” Table in Technical Manual
    Electrobrightening (also called Electro Polishing and Electrolytic Brightening)
    Improving the specular reflectivity of a metal surface by electrochemical dissolution. High-purity aluminum is required for good brightness. See also Bright Dip)
    Elongation
    The increase in the gauge length of a tensile test specimen, between two marks 2 inches apart, expressed as a percent, after stressing the specimen in tension to the point of fracture.
    Embossing
    Raising or indenting a design in relief on a sheet or strip of metal by passing between two patterned rolls.
    Etching
    Subjecting the surface of a metal to preferential chemical or electrolytic attack to reveal structural details.
    Extensometer
    A test apparatus for indicating the deformation of metal while it is subjected to stress.
    Eye to the Side
    Packed on a skid so that the coils are standing on edge and the ID is horizontal (less common)
    Eye to the Sky
    Packed on a skid so the coils are laying flat and ID is vertical (common packing procedure)
    F Temper
    “As Fabricated” Applies to products of rolling or forming where there is no special control over the thermal or work hardening conditions. Mechanical properties may vary widely. This temper usually applies to sheet products at intermediate stages of production. See “Aluminum Temper Designations” section of Technical Manual
    Fatigue Limit
    The maximum stress below which a material can presumably endure an infinite number of stress cycles.
    Fiber
    The characteristic of wrought metal that indicates directional properties. It is revealed by etching a longitudinal section or manifested by the fibrous appearance of a fracture.
    Fin Stock
    Coiled Sheet or foil in specific alloys, tempers and thickness ranges suitable for manufacture fins for heat exchanger applications.
    Flatness
    For rolled products, a distortion of the surface of sheet such as a bulge or a wave, usually transverse to the direction of rolling. Often described by location across width, i.e., edge buckle, quarter buckle, center buckle, etc.
    Flat Sheet
    Sheet with sheared, slit or sawed edges, which has been flattened or leveled.
    Flow Lines
    Texture showing the direction of metal flow during hot or cold working. Flow lines often can be revealed by etching the surface or a section of a metal part.
    Flow Stress
    The shear stress required to cause plastic deformation of solid metals.
    Flux Dip Brazing
    The component is immersed in a molten salt which acts as a flux as well as a heat source for melting the clad layer. The fluxes are corrosive and all traces must be removed after brazing. (See Brazing) See United Aluminum Capabilities data for information on Brazing Sheet offered
    FMEA
    Failure Mode and Effects Analysis, a component of QS 9000.
    Foil
    A cold-rolled aluminum strip product that has thickness less than 0.006 inch (less than 0.20 mm in Europe).
    Formability
    The relative ease with which a metal can be shaped through plastic deformation.
    Four-High Mill
    Common rolling mill for reducing the thickness of aluminum sheet consisting of two large diameter work rolls which are supported by even larger back-up rolls.
    Fretting (Fretting Corrosion)
    Action that results in surface damage, especially in a corrosive environment, when there is relative motion between solid surfaces in contact under pressure. Also commonly called “traffic marking”.
    Friction Gouges or Scratches
    A series of relatively short surface scratches variable in form and severity. Refer to Galling.
    Full Hard Temper
    In non-heat treatable alloys, it is the hardest temper obtainable by hard cold rolling.
    Galling
    The damaging of one or both metallic surfaces by removal of particles from localized areas due to seizure during sliding friction. Developing a condition on the rubbing surface of one or both mating parts where excessive friction between high spots results in localized welding with substantial spalling and a further roughening of the surface.
    Gauge
    Commonly used to describe the thickness of aluminum sheet or coil in inches / millimeters. Not to be confused with comparative gauges such as Brown & Sharpe, US Standard, and Manufacturers sheet steel, which use a number to designate a non-corresponding thickness, IE “20 Gauge” is .032″ on the Brown & Sharpe scale.
    Gouge
    A gross scratch.
    Grain
    (Direction of) Refers to grain fiber following the direction of rolling and parallel to edges of strip or sheets. (2) To bend across the grain is to bend at right angles to the direction of rolling. (3) To bend with the grain is to bend parallel to the direction of rolling.
    Grain Coarsening
    A heat treatment that produces excessively large austenitic grains.
    Grain Size
    For metals, a measure of the areas or volumes of grains in a polycrystalline material, usually expressed as an average when the individual sizes are fairly uniform. Grain sizes are reported in terms of grains per unit area or volume, average diameter, or as a grain-size number derived form area measurements. Average diameter of grains in the metal under consideration, or alternatively, the number of grains per unit area.
    HXX Temper
    Strain hardened temper. Applies to wrought products which are strengthened by cold-rolling or cold working. See “Aluminum Temper Designations” section of Technical Manual
    H1X Temper
    Strain hardened only. See “Aluminum Temper Designations” section of Technical Manual
    H2X Temper
    Strain hardened and partially annealed. See “Aluminum Temper Designations” section of Technical Manual
    H3X Temper
    Strain hardened and stabilized See “Aluminum Temper Designations” section of Technical Manual
    Handling Mark
    An area of damaged or broken surface introduced after processing. Not related to the rolling direction.
    Hair, Slitter
    Minute hair-like sliver along edge(s) due to shearing or slitting operation.
    Heat Treating / Heat Treated
    Process of heating and cooling a metal or alloy in a controlled process to achieve desired properties. Commonly Used to refer to “T” tempering to increase strength characteristics of heat-treatable alloys. See “Heat Treatment Tempers” section of the Technical Manual.
    Heat-Treatable Alloys
    Alloys in the 2XXX, 6XXX and 7XXX series can be strengthened by heat-treating. United Aluminum can offer Alloys in each of these series. See “Capabilities”
    Herringbone
    Elongated alternate bright and dull markings at an angle to the rolling direction and having the appearance of a herringbone pattern.
    Hole
    Void in rolled product. Typical cause is a non-metallic inclusion during rolling.
    Holiday
    Region where film is absent due to non-wetting of the metal surface by the coating.
    Hot Mill Pickup
    Small particles of aluminum and aluminum oxide generated in the roll bite which subsequently transfer to the rolled product. It may be distributed uniformly and/or in streaks.
    ID
    Abbreviation for inside diameter of a coil.
    Inclusion
    Particles of impurities (usually oxides, sulfides, silicates, etc.) that are held mechanically or are formed during the solidification or by subsequent reaction within the solid metal.
    Inclusion, Stringer
    An impurity, metallic or non-metallic, which is trapped in the ingot and elongated subsequently in the direction of working. It may be revealed during working or finishing as a narrow streak parallel to the direction of working.
    Ingot
    A cast block of aluminum for subsequent rolling or forging.
    Interleaving
    The placing of a sheet of paper between two adjacent layers of metal to facilitate handling and shearing of rectangular sheets, or to prevent sticking or scratching.
    Ironing
    Thinning the walls of deep drawn articles by reducing the clearance between punch and die.
    ISO
    International Standardization Organization, a worldwide federation of national standards bodies. Some common ISO standards that are encountered in aluminum manufacturing are:
    ISO 9000, ISO 9001 – comprehensive quality management system. Specific details are given in ISO 9001.
    ISO 14000, ISO 14001 – environmental management guide.
    ISO 16949 – a variation of ISO 9000 that is applicable to the automotive industry.
    ISO 17025 – standard used for accreditation of test laboratories.
    Isotropy
    See Earing
    JIS
    Japanese Industrial Standard. The common standard for aluminum coiled sheet is JIS H P4000.
    Knife Mark (also known as Cutter Mark)
    A continuous scratch (which may also be creased) near a slit edge, caused by sheet contacting the slitter knife.
    Lamination
    An abnormal structure resulting in a separation aligned generally parallel to the worked surface of the metal.
    Lateral Bow
    See Also “Camber” An edgewise curvature referring to the deviation of side edge from a straight line. See “Lateral Bow Limits” section of Technical Manual
    Leveling / Leveled
    Flattening rolled metal sheet or strip by various methods, including “roller”, “stretcher”, “tension”, or “thermal”.
    Longitudinal Bow
    A longitudinal curvature in the plane of a sheet.
    Looper (also known as Parabolics and Roping)
    Parabolic lines or marks on the sidewalls of deep-drawn cups. A manifestation of the rolling direction of the sheet surface. The grain structure and any longitudinal scratches will show as a parabolic pattern on the sidewalls.
    Loose Wrap
    A condition in a coil due to insufficient tension which creates a small void between adjacent wraps.
    Luder Lines
    Surface markings resulting from localized flow which appear on some alloys after light straining. They lie approximately parallel to the direction of the applied maximum shear stress (about 45 degrees to the direction of the applied stress).
    Machinability
    The relative ease of machining a metal.
    Malleability
    The property that determines the ease of deforming a metal when the metal is subjected to rolling or hammering.
    Mark
    Damage in the surface of the product whose name is often described by source.
    Mark, Chatter (Roll or Leveler)
    Numerous intermittent lines or grooves that are usually full width and perpendicular to the rolling direction.
    Mark, Handling
    Surface damage that is introduced after processing. The mark usually has no relationship to the rolling direction.
    Mark, Inclusion
    Appearance of surface where actual inclusion or the void it left is observed.
    Mark, Knife
    See Knife Marks (also known as Cutter Marks)
    Mark, Roll
    Small repeating raised or depressed area caused by the opposite condition on a roll. The repeat distance is a function of the offending roll diameter.
    Mark, Rub
    A large number of very fine scratches or abrasions. A rub mark can occur by metal-to-metal contact, movement in handling and movement in transit.
    Mark, Traffic
    Abrasion which results from relative movement between contacting metal surfaces during handling and transit. A dark color from the abrasively produced aluminum oxide is usually observed. A mirror image of a traffic mark is observed on the adjacent contacting surface. See also “fretting”
    Mechanical Properties
    The properties of a material, including Tensile Strength, Yield, and elongation, typically used to assess its suitability for a particular application relative to other alloys. See “Typical Mechanical Properties” section of the Technical Manual
    Mill Edge
    The edge of strip, sheet or plate in the as rolled state. Unsheared.
    Mill Finish
    A surface finish produced on sheet and plate. Characteristic of the ground finish used on the rolls in fabrication. See Capabilities for available finishes.
    Minimum Recommended Bend Radii
    Minimum radii expressed in terms of thickness for bending sheets and plates without fracturing in a standard press brake with air bend dies. See “Recommended Minimum Bend radii for 90-Degree Cold Forming of Sheet” in the Technical Manual section.
    Modulus of Elasticity
    Ratio of stress, within proportional limit, to corresponding strain.
    Modulus of Elasticity (tension)
    The ratio of stress to strain within the perfectly elastic range.
    Mult
    Aluminum sheet is generally rolled at much wider widths than the finished width. The family of narrow coils that are slit from a wide coil is called a mult. Each individual narrow coil is called a cut.
    Necking
    Local reduction of the cross-sectional area of metal by stretching.
    Nick
    A surface or edge discontinuity in the form of a slight cut, indentation, or notch. Also referred to as “Scratch” and “Gouge”.
    Non-Ferrous Metals
    Metals or alloys that are free of iron or comparatively so.
    Non Heat-Treatable Alloy
    The correct term for the 1XXX, the 3XXX, the 5XXX alloy classes. These alloys gain strength only through cold working and lose strength through thermal treatments. They are also called the soft or common alloys.
    OD
    Abbreviation for outer diameter of a coil.
    O Temper
    Annealed temper. Applies to wrought products which have been heated above the re-crystallization temperature to produce the lowest tensile condition of the alloy. See “Aluminum Temper Designations” section of Technical Manual
    Oil Stain
    Stain produced by the incomplete burning of the lubricants on the surface of the sheet. Rolling subsequent to staining will change color from darker browns to lighter browns down to white.
    Orange Peel (effect)
    A surface roughening (defect) encountered in forming products from metal that has a coarse grain size. It is due to uneven flow or to the appearance of the overly large grains, and may be the result of annealing at too high a temperature.
    Oscillation
    Uneven wrap in coiling and lateral travel during winding. Improper alignment of rolls over which the metal passes before rewinding and insufficient rewind tension are typical causes. See also “Telescoping.”
    Oxidation
    Exposure to atmosphere sometimes results in oxidation of the exposed surface, hence a staining or discoloration. This effect is increased with temperature increase. A reaction in which there is an increase in valence resulting from a loss of electrons. Chemical combination with oxygen to form an oxide. For aluminum, see Waterstain.
    Pad
    See Cut.
    Pancake coil
    Term sometimes used to describe a narrow-slit coil that is eye-to-sky.
    Parabolics
    See Loopers
    Physical Properties
    Properties other than mechanical properties, that pertain to the physical nature of a material such as thermal expansion, melting range, density, thermal conductivity, Electrical conductivity, reflectivity, etc. See the “Typical Physical Properties” table in the Technical Manual section
    Pickup
    Small particles of oxide adhering to the surface of the aluminum sheet, usually originating from the hot-rolling operation. Adhesion of metal to punches and dies of deep-drawing tooling is also called pickup.
    Pit (defect)
    A sharp depression or mark in the surface of the metal.
    PIW
    Pounds Per inch of Width. See “Coil Size Calculator” section of the Technical Manual.
    Polished Surface
    The finish obtained by buffing with rouge or similar fine abrasive, resulting in a high gloss or polish.
    PPAP
    Production Part Approval Process, a component of QS 9000.
    Published Tolerances
    A term sometimes used synonymously with “Standard” or “Commercial” tolerances. See Commercial Tolerances.
    PVC
    Type of strippable plastic that is applied to protect a surface from scratching and marking.
    QS 9000
    Quality system requirements for the automotive industry. Superceded by ISO 16949
    Quarter Hard
    Applicable to strain hardened (cold worked) alloys where the degree of strain hardening is approximately 1/4 of the way between O temper and the full hard condition (HX8). See HX2 tempers.
    Quarter Buckle
    Undulation (wavy region) which occurs approximately at both quarter points across the width.
    Quenching
    Rapid cooling. In the heat-treating of metals, the step of cooling metals rapidly in order to obtain desired properties; most commonly accomplished by immersing the metal in oil or water.
    Ra
    See Surface Roughness
    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.
    Reroll Stock
    A semi finished rolled product of rectangular cross-section in coiled form suitable for further rolling.
    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.
    Roll Forming
    An operation used in forming sheet by passing between rolls of definite settings that bend the sheet progressively into the desired shape.
    Roll Chatter
    Numerous intermittent lines or grooves that are usually full width and perpendicular to the rolling direction.
    Roll Mark
    A raised area formed during rolling by the imprint of a depression in a roll.
    Roll Pickup
    Small particles of aluminum and aluminum oxide generated in the roll bite which subsequently transfer to the rolled product. It may be distributed uniformly and/or in streaks.
    Rolled-In Scratch
    A scratch that occurs during the fabricating process and is subsequently rolled over.
    Rolling
    Reducing the cross-sectional area of metal stock through the use of rotating rolls. 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.
    Roping
    See Loopers
    Rz
    See Surface Roughness
    SAE
    Abbreviation for Society of Automotive Engineers.
    Scratch
    A sharp linear indentation in the surface of the metal.
    Scratch, Friction
    A scratch caused by relative motion between two contacting surfaces.
    Scratch, Handling
    A more severe form of rub mark, created by other than processing.
    Scratch, Oscillation
    Minor indentations at an angle to the rolling direction that result from coil oscillation during unwinding or rewinding.
    Scratch, Rolled-In
    A scratch which is subsequently rolled.
    Scratch, Tension
    A short longitudinal indentation parallel to the rolling direction.
    Sendzimir Mill (Z Mill)
    A mill having two work rolls of 1 to 2 1/2-in diameter each, backed up by two rolls twice that diameter and each of these backed up by bearings on a shaft mounted eccentrically so that rotating it increases the pressure between bearings and backup rolls. See Picture
    Shear Strength
    The stress required to produce fracture in the plane of cross section, the conditions of loading being such that the directions of force and of resistance are parallel and opposite although their paths are offset a specified minimum amount.
    Sheet
    A flat-rolled metal product of some maximum thickness and minimum width arbitrarily dependent on the type of metal. Sheet is thinner than plate. Varieties include Alclad, Anodizing, Clad, Coiled, Flat, painted, etc)
    Slit Edges
    The edges of sheet or strip metal resulting from cutting to width by rotary slitters.
    Slitting
    A high-speed method of cutting sheet in coiled form to narrower width coils. See Picture
    Slitter Hair
    Minute hair-like silver along edge(s) due to shearing or slitting operation.
    Sliver (defect)
    Loose metal piece rolled down onto the surface of the metal during the rolling operations.
    Smut
    A dark film of debris, sometimes covering large areas, deposited on the sheet during rolling. Also referred to as “Smudge”.
    Solution Heat Treatment
    A heat treatment in which an alloy is heated to a suitable temperature, held at that temperature long enough to cause one or more constituents to enter into solid solution, and then cooled rapidly enough to hold these constituents in solution.
    Stain, Oil
    Surface discoloration which may vary from dark to brown to white and is produced during thermal treatment by incomplete evaporation and/or oxidation of lubricants on the surface.
    Stain, Water
    (See Water Stain) Superficial oxidation of the surface with a water film, in the absence of circulating air, held between closely adjacent metal surfaces. See the “Waterstain and its Prevention” section of the Technical Manual.
    Stamping
    A term used to refer to various press forming operations in coining, embossing, blanking, and pressing.
    Strain
    A measure of the relative change in the size of a body. Linear strain is the change per unit length of a linear dimension. True (or natural) strain is the natural logarithm of the ratio of the length at the moment of observation to the original gauge length. Shearing strain is the change in angle (expressed in radians) between two reference lines originally at right angles. When the term is used alone, it usually refers to linear strain in the direction of the applied stress.
    Stress
    Force per unit of area. Stress is normally calculated on the basis of the original cross-sectional dimensions. There are three kinds of stresses: tensile, compressive, and shear.
    Stress-Rupture Test
    A tension test performed at constant temperature, the load being held at such a level as to cause rupture.
    Stretch Forming
    A process of forming panels and cowls of large curvature by stretching sheet over a form of the desired shape. This method is more rapid than hammering and beating.
    Stretcher Leveling
    A method of making metal sheet or strip flat by stretching.
    Strip
    A sheet of metal whose length is many times its width. Also called coil, coiled strip, rolls, or bands.
    Structure
    The arrangement of parts; in crystals, especially, the shape and dimension of the until cell, and the number, kinds and positions of the atoms within it.
    Substrate
    The layer of metal underlying a coating, regardless of whether the layer is base metal.
    Surface Roughness
    The surface texture measured using a stylus instrument across the rolling direction. The most common parameters are:
    Ra – Arithmetic Average Roughness measures the height of irregularities from the mean line within the sampling length. This is the
    universally recognized and most common parameter for surface roughness.
    Rq – Root Mean Square (RMS) measures the average height of irregularities from the mean line using a different formula to Ra.
    Once a common method, it is now seldom used.
    Ry – Maximum Peak-to-Valley Height is sensitive to high peaks and deep scratches.
    Rz (ISO) – Ten-Point Height is the average distance between the five highest peaks and five deepest valleys measured from a
    reference line.
    Tandem Mill
    Arrangement of rolling mills, in direct line, allowing the metal to pass from one set of rolls into the next.
    Telescoping
    Transverse slipping of successive layers of a coil so that the edge of the coil is conical rather than flat.
    Temper
    The condition of an alloy produced by mechanical and/or thermal treatment, and characterized by certain mechanical properties and structure. See also “Temper Designations” section of the Technical Manual
    Tensile Strength
    Also called “ultimate strength”. Breaking strength of a material when subjected to a stretching force. Usually measured by placing a standard test piece in the jaws of a tensile machine, gradually separating the jaws, and measuring the stretching force necessary to break the test piece. Tensile strength is commonly expressed as pounds (or tons) per square inch of original cross section.
    Thickness
    See Gauge
    Tolerance
    Allowable deviation from a nominal or specified dimension. The term “commercial tolerance” generally refers to those allowable tolerances published by the Aluminum Association. See Thickness and Width tolerances section of Technical Manual
    Traffic Marks
    Abrasions resulting from relative movement between contacting metal surfaces during transit. These abrasions are usually dark in appearance due to the presence of aluminum and aluminum oxide fines produced by the abrasive action.
    Transverse Bow
    Curvature across the width of sheet or coil.
    Transverse Direction
    A direction perpendicular to the direction of working or rolling.
    Ultimate Strength
    See Tensile Strength
    Ultimate Tensile Strength (UTS)
    Another common term to describe mechanical strength. This metal property is expressed in thousands of pounds per square inch and denotes how much stress can be gradually applied to the metal before it fractures. Tensile testing is done by pulling two ends of a test sample in opposite directions under a constantly increasing force, subjecting the product to stress. The stress is measured until the product is pulled in two. The measurement at the exact time of fracture is the material’s ultimate tensile strength.
    Vacuum Brazing
    Components are heated in a high vacuum, completely free of oxygen. The clad alloy must contain magnesium as an alloying addition. At the brazing temperature, the heat and vacuum causes the magnesium to “boil” out of the molten metal thereby breaking up the brittle oxide skin into small, harmless shards. (See Brazing) See United Aluminum Capabilities data for information on Brazing Sheet offered
    Water Stain
    White, chalky patches formed after aluminum comes in contact with water or condensation. See “Waterstain and its Prevention” in the Technical Manual section.
    Wavy
    Not flat. A slight wave following the direction of rolling and beyond the standard limitation for flatness.
    Wavy Edge
    A rippling departure of an edge from flat.
    Weldability
    Suitability of a metal for welding under specific conditions.
    Workability
    The characteristic or group of characteristics that determines the ease of forming a metal into desired shapes.
    Wrought Product
    Products which began as raw material castings and are mechanically worked by processes such as rolling, extruding, forging, etc.
    Yield Point
    The first stress in a material, usually less than the maximum attainable stress, at which an increase in strain occurs without an increase in stress. Only certain metals exhibit a yield point. If there is a decrease in stress after yielding, a distinction may be made between upper and lower yield points.
    Yield Strength (also known as Proof Stress)
    A property of the material that describes the stress at which the material exhibits a specified permanent set. That is the point at which it will not spring back to its original length when stress on the material is relieved. For aluminum the yield strength is usually measured at the point where the stress applied to the material causes a 0.2% (of the gauge length) permanent set.
    Z-Mill
    “Z Mill” or Sendzimir mill. A mill having two work rolls of 1 to 2 1/2-in diameter. each, backed up by two rolls twice that diameter and each of these backed up by bearings on a shaft mounted eccentrically so that rotating it increases the pressure between bearings and backup rolls. See Picture