The International Annealed Copper Standard (IACS) is a

standard Standard may refer to: Symbols * Colours, standards and guidons, kinds of military signs * Standard (emblem), a type of a large symbol or emblem used for identification Norms, conventions or requirements * Standard (metrology), an object th ...

established in 1914 by the United States Department of Commerce. It is an empirically derived standard value for the electrical conductivity of commercially available

copper Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkis ...

. Sometime around 1913 several copper samples from 14 important refiners and wire manufacturers were analyzed by the U.S. Bureau of Standards. The average resistance of the samples was determined to be 0.15292 Ω for copper wires with a mass of 1

gram The gram (originally gramme; SI unit symbol g) is a unit of mass in the International System of Units (SI) equal to one one thousandth of a kilogram. Originally defined as of 1795 as "the absolute weight of a volume of pure water equal to th ...

of uniform

cross section Cross section may refer to: * Cross section (geometry) ** Cross-sectional views in architecture & engineering 3D *Cross section (geology) * Cross section (electronics) * Radar cross section, measure of detectability * Cross section (physics) **Abs ...

and 1

meter The metre (British spelling) or meter (American spelling; see spelling differences) (from the French unit , from the Greek noun , "measure"), symbol m, is the primary unit of length in the International System of Units (SI), though its pref ...

in length at 20 °C. In the United States this is usually written as "0.15292 ohm (meter, gram) at 20 °C". Germany proposed a slight modification of this value to "0.15328 ohm (meter, gram) at 20 °C", this being equivalent to a conductivity of exactly at 20 °C. The German modification was adopted by the International Electrotechnical Commission in 1913 and subsequently published by the

United States Department of Commerce The United States Department of Commerce is an executive department of the U.S. federal government concerned with creating the conditions for economic growth and opportunity. Among its tasks are gathering economic and demographic data for bus ...

on October 1, 1914 as the International Annealed Copper Standard (IACS). The standard is most often used as a comparative property in the specification of the conductivity of other metals. For example, the conductivity of a particular grade of

titanium Titanium is a chemical element with the Symbol (chemistry), symbol Ti and atomic number 22. Found in nature only as an oxide, it can be reduced to produce a lustrous transition metal with a silver color, low density, and high strength, resista ...

may be specified as 1.2 % IACS, meaning that its electrical conductivity is 1.2 % of the copper specified as the IACS standard. The standard can be found at https://archive.org/stream/copperwiretables31unituoft#page/n0/mode/1up.

Quality of aluminum alloys

Heat treatment Heat treating (or heat treatment) is a group of industrial process, industrial, thermal and metalworking, metalworking processes used to alter the physical property, physical, and sometimes chemical property, chemical, properties of a material. ...

will alter several properties of an alloy, many of which are important to a design engineer. A measurement of the electric conductivity of aluminum alloys can be used to verify that a heat treatment process has been done correctly. For example a component made of "7075" alloy which was correctly treated with the process "T73" to gain resistance to stress corrosion cracking will fall in the range of 38.0 to 43.0 % IACS. The acceptance criteria for electrical conductivity of finished or semi-finished parts of wrought aluminum alloys are contained in

SAE International SAE International, formerly named the Society of Automotive Engineers, is a United States-based, globally active professional association and standards developing organization for engineering professionals in various industries. SAE Internatio ...

specification AMS2658 Hardness and Conductivity Inspection of Wrought Aluminum Alloy Parts. Here the values are given in reference to the IACS. A method for measuring electrical conductivity is described in

ASTM International ASTM International, formerly known as American Society for Testing and Materials, is an international standards organization that develops and publishes voluntary consensus technical standards for a wide range of materials, products, systems, ...

specification ASTM E 1004 Electromagnetic (Eddy-Current) Measurements of Electrical Conductivity. Electrical conductivity meters with direct readout in %IACS are commercially available.

References

{{reflist Copper International standards