Carbon

arc welding Arc welding is a welding process that is used to join metal to metal by using electricity to create enough heat to melt metal, and the melted metals, when cool, result in a binding of the metals. It is a type of welding that uses a welding powe ...

(CAW) is a process which produces coalescence of metals by heating them with an arc between a non-consumable

carbon Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent In chemistry, the valence (US spelling) or valency (British spelling) of an element is the measure of its combining capacity with o ...

(

graphite Graphite () is a crystalline form of the element carbon. It consists of stacked layers of graphene. Graphite occurs naturally and is the most stable form of carbon under standard conditions. Synthetic and natural graphite are consumed on large ...

)

electrode An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit (e.g. a semiconductor, an electrolyte, a vacuum or air). Electrodes are essential parts of batteries that can consist of a variety of materials de ...

and the work-piece. It was the first arc-welding process developed but is not used for many applications today, having been replaced by twin-carbon-arc welding and other variations. The purpose of arc welding is to form a bond between separate metal pieces. In carbon-arc welding a carbon electrode is used to produce an electric arc between the electrode and the materials being bonded. This arc produces temperatures in excess of 3,000 °C. At this temperature the separate metals form a bond and become welded together.

Development

CAW could not have been created if not for the discovery of the

electric arc An electric arc, or arc discharge, is an electrical breakdown of a gas that produces a prolonged electrical discharge. The electric current, current through a normally Electrical conductance, nonconductive medium such as air produces a plasma (p ...

Humphry Davy Sir Humphry Davy, 1st Baronet, (17 December 177829 May 1829) was a British chemist and inventor who invented the Davy lamp and a very early form of arc lamp. He is also remembered for isolating, by using electricity, several elements for t ...

in 1800, later repeated independently by a Russian physicist

Vasily Vladimirovich Petrov Vasily Vladimirovich Petrov (russian: Василий Владимирович Петров) ( – 15 August 1834) was a Russian experimental physicist, self-taught electrical technician, academician of Russian Academy of Sciences (since 1809; C ...

in 1802. Petrov studied the electric arc and proposed its possible uses, including

welding Welding is a fabrication (metal), fabrication process that joins materials, usually metals or thermoplastics, by using high heat to melt the parts together and allowing them to cool, causing Fusion welding, fusion. Welding is distinct from lower ...

. The inventors of carbon-arc welding were

Nikolay Benardos Nikolay Nikolayevich Benardos (russian: Никола́й Никола́евич Бенардо́с) (1842–1905) was a Russian inventor of Greek origin who in 1881 introduced carbon arc welding, which was the first practical arc welding method. ...

and Stanisław Olszewski, who developed this method in 1881 and patented it later under the name ''Elektrogefest'' ("

Electric Electricity is the set of physical phenomena associated with the presence and motion of matter that has a property of electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described by ...

Hephaestus Hephaestus (; eight spellings; grc-gre, Ἥφαιστος, Hḗphaistos) is the Greek god of blacksmiths, metalworking, carpenters, craftsmen, artisans, sculptors, metallurgy, fire (compare, however, with Hestia), and volcanoes.Walter Burk ...

").

Variations

* Twin carbon arc welding (TCAW) in which the arc is established between two carbon electrodes * Gas carbon arc welding (CAW-G) no longer has commercial significance. Other processes that use shielding gases have also replaced carbon-arc welding such as ''tungsten-arc welding'' (GTAW, or TIG), ''plasma-arc welding'' (PAW), and ''atomic-hydrogen welding'' (AHAW). Each of these processes, including carbon-arc welding, use a nonconsumable electrode. A filler metal is generally used to aid the bond in the workpieces.

Development

Variations

References