Terms and Definitions

In order to understand the properties of wrought copper and copper alloys it is necessary to be familiar with some of the common terms used to describe them. Some of the terms will apply to all metals and processes while others are specific to copper and copper alloys. A list of terms and definitions which will be used in this series appear below. This is only a partial list and a more complete listing of terms and definitions appears in "Standards Handbook, Part 3" published by Copper Development Association Inc.


A substance having metallic properties and composed of two or more elements, at least one of which is a metal.


A process involving heating and cooling designed to effect:
  1. a softening of a cold-worked structure by re-crystallization or grain growth or both;
  2. softening of an age-hardened alloy causing a nearly complete precipitation of the second phase in a relatively coarse form;
  3. softening of certain age-hardenable alloys by dissolving the second phase and cooling rapidly enough to obtain a supersaturated solution;
  4. relief of residual stress.

Area Reduction

The decrease in cross-section of a product by rolling or drawing. This is a measure of the temper of metal in the cold worked condition.


Abbreviation for American Society of Materials International, ASM International


Abbreviation for American Society of Testing Methods


Abbreviation for American Welding Society Back to Top


A piece from any wrought product intended for subsequent fabrication such as forming, bending, cupping, drawing or hot pressing.


Any copper alloy with zinc as the principal alloying element, with or without small quantities of some other elements.


Originally a term for copper alloys having tin as the only principle alloying element. In modern usage the term "Bronze" is seldom used alone, and the terms "Phosphor Bronze" or "Tin Bronze" is used for indicating copper-tin alloys. In fact the term "Bronze", together with a suitable modifying adjective has in recent years been extended to apply to any of a great variety of copper alloys.


A fabrication method of securing a smooth finished surface by slight deformation with highly polished tools.


The thin ridge or roughness left by a cutting operation such as slitting, shearing, blanking or sawing. Back to Top


Abbreviation for Copper Development Association Inc.


The beveled surface normally at a 15o to 45o angle, to break a sharp corner or edge.

Cold Working

The process of changing the form or cross section of a piece of metal at a temperature below the softening or recrystallization point, but commonly at or about room temperature. It includes rolling, drawing, pressing and stretching.

Commercially Pure Copper

Metal for which the specified minimum copper content is not less than 99.88%, silver being counted as copper.


Metal for which the specified minimum copper content is less than 99.88% and not less than 99.3%, silver being counted as copper.

Copper Alloy

Metal for which the specified minimum copper content is less than 99.3% and not less than 40% and having no other element specified in excess of the copper content; exception to this definition occurs in the case of copper-nickel-zinc alloys where zinc slightly exceeds the copper content in certain alloys which are commonly designated as copper alloys.


The deterioration or failure of metals and alloys by chemical or electrochemical processes.
  1. Dealuminification - A phenomenon somewhat similar to dezincification involving loss of aluminum.
  2. Denickelification - A phenomenon somewhat similar to dezincification involving loss of nickel.
  3. Dezincification - Corrosion of an alloy containing zinc (usually brass) involving loss of zinc.
  4. Erosion - The abrasion of metal or other material by liquid or gas, usually accelerated by presence of solid particles of matter in suspension, and sometimes by corrosion.
  5. Stress Corrosion - Spontaneous failure of metals by cracking under combined action of corrosion and stress, residual or applied.


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 in the vicinity of the recrystallization temperature of the metal.


The variation in thickness across the product from edge to center or edge to edge. Back to Top


Removing rough or sharp edges left on metal by cutting operations.


The transverse departure of the concave surface from a straight line from edge to edge.


The property of a metal that permits permanent deformation before fracture by stress in tension. Back to Top

Edgewise Curvature

The lateral departure of the edge from a straight line which may be unidirectional or reversing; in the latter case sometimes called snaky.


The permanent extension of a specimen which has been stretched to rupture in a tension test. The percentage elongation is an indication of ductility. Back to Top


The tendency for a metal to break under conditions of repeated cyclic stressing considerably below the ultimate tensile strength.


The condition of the surfaces of the products, produced by normal or special mill procedures. Finishes include Acid Dipped-Dry Rolled, Bright Annealed, Bright Dipped, Buffed Surface, Clean Annealed, Dry Rolled, Scratch Brushed, as well as many others.

Finished Edges

Smooth edges produced on flat wire , strip or bar by drawing or rolling with or without previous slitting. The edge contours most commonly used are Square Corners, Rounded Corners, Rounded Edges and Full Rounded Edges.


The degree to which a surface of a flat product approaches a plane.

Flat Product

A product with rectangular or square solid section and relatively great length in proportion to thickness.
  • Drawn Flat Product - Flat product brought to final dimensions by drawing through a die, and furnished in flat straight lengths, on spools, or in rolls. The corners or edges may be square or of other contours.


The mill operation performed on rolled flat products to reduce departure from flatness, such as curl and dish.


A term often applied to a thin flat rolled section usually 0.005 inches or less in thickness. Back to Top


A solid polyhedral crystal consisting of groups of atoms bound together in a regular geometric pattern.

Grain Growth

The process by which individual grains coalesce to form larger and , therefore, fewer grains. This is usually brought about by annealing and results in the softening of the metal as well as changes in other properties.

Grain Size

The average diameter of grains, usually determined microscopically, on an etched plane surface of the metal. Back to Top


The resistance of metal to plastic deformation by indentation. The most common method of measurement is Rockwell. Other methods are Brinell, Scleroscope, Tukon and Vickers. Back to Top


Abbreviation for International Annealed Copper Standard.

Internal Stress

See Stress, Residual. Back to Top

Orange Peel Surface

The surface roughness resulting from working metal of large grain size. The surface is similar in texture to an orange peel. Back to Top


The change in grain structure which occurs when the metal is annealed, during which the deformed grains, strain hardened by working, become new unstrained grains.

Reduction in Area

The permanent reduction in area of a specimen which has necked in a tension test. The percentage reduction in area is an indication of ductility.


A slight transverse wave or shadow mark repeated at intervals, sometimes observed on flat products. Back to Top

Sheared Edges

The edges resulting from press shearing to final width and length. These edges are straighter than slit edges.


A flat rolled product up to and including 0.188 inches in thickness and over 20 inches in width.

Slit Edges

The edges resulting from cutting to width with rotary slitters.

Straightening and Flattening

Any process applied to flat rolled products to eliminate any general or local curvature, either with respect to flatness or edgewise curvature.
  1. Roll Flattening - The process of flattening a product by a machine with a number of small diameter cylindrical rolls so positioned as to repeatedly flex the product and thus remove certain irregularities in shape. Roll flattening practically eliminates longitudinal curl, burr and dish. It reduces edgewise curvature of narrow strip. This operation reduces buckles, but is relatively ineffective in eliminating wavy edges, ripples and twist. Roll flattening is ordinarily applied to Flat Rolled Products within the approximate size range 0.010 to 1/8 inches thick and in widths to about 48 inches, and is particularly effective on annealed tempers, but ids progressively less effective with increase in degree of rolled temper.
  2. Stretcher Flattening, (Patent Leveling) Applicable to flat straight lengths - A process which simultaneously flattens and straightens a product by longitudinally stretching it beyond its elastic limit. This process practically removes buckles, ripples, wavy edges, twist and edgewise curvature, is partially effective in removing longitudinal curl but is ineffective in removal of crown, dish and burr. It is commonly applied to flat rolled products within the approximate size range of 0.012 to 0.050 inches thick and 3 to 48 inches wide. It is particularly effective on all annealed tempers and on rolled tempers up to half hard.


  1. Applied Stress - Stresses that are set up and exist in a body during application of an external load.
  2. Residual Stress - Stresses that remain within a body as the result of plastic deformation, casting or rapid temperature change.


A flat product, other than flat wire, up to and including 0.188 inches in thickness and generally furnished as follows:
  1. With slit, sheared or slit and edge rolled edges in widths up to 20 inches inclusive
  2. With finished drawn or rolled edges in widths over 1 inches to 12 inches inclusive.
Back to Top


The condition produced in a metal by mechanical or thermal treatment and having characteristic structure and mechanical properties.

Tensile Strength

The value obtained by dividing the maximum load observed during tensile straining by the specimen cross-sectional area before straining. Also called "Ultimate Strength". It is usually expressed in pounds per square inch.


The amount by which any characteristic, such as dimensional, chemical, physical or mechanical properties may vary from that specified.


A winding departure from flatness. Back to Top

Wavy Edges

A wrinkled condition along the edges of the product, with a relatively flat center portion. Back to Top

Yield Strength

As commonly applied to copper and copper alloys, yield strength is the stress which will produce an extension of 0.50 percent under load. It is known as Yield Strength at 0.50 percent extension.