Carbon arc welding
Encyclopedia
Carbon arc welding
(CAW) is a process which produces coalescence of metals by heating them with an arc between a nonconsumable carbon
(graphite
) electrode
and the work-piece. It was the first arc-welding process ever developed but is not used for many applications today, having been replaced by twin-carbon-arc welding and other variations.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 metals. 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 extreme temperatures in excess of 3,000°C. At this temperature the separate metals form a bond and become welded together.
by Sir Humphry Davy in 1800, later repeated independently by a Russian physicist Vasily Vladimirovich Petrov
in 1802. Petrov studied electric arc and proposed its possible ways of usage, including for welding
.
The inventor of carbon-arc welding was another Russian, Nikolay Benardos
, who developed this method in 1881 and patented it later under the name Elektrogefest ("Electric Hephaestus
").
(Picture provided by Answers.com, http://www.answers.com/topic/carbon-arc-welding?cat=technology)
Arc welding
Arc welding is a type of welding that uses a welding power supply to create an electric arc between an electrode and the base material to melt the metals at the welding point. They can use either direct or alternating current, and consumable or non-consumable electrodes...
(CAW) is a process which produces coalescence of metals by heating them with an arc between a nonconsumable carbon
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...
(graphite
Graphite
The mineral graphite is one of the allotropes of carbon. It was named by Abraham Gottlob Werner in 1789 from the Ancient Greek γράφω , "to draw/write", for its use in pencils, where it is commonly called lead . Unlike diamond , graphite is an electrical conductor, a semimetal...
) electrode
Electrode
An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit...
and the work-piece. It was the first arc-welding process ever developed but is not used for many applications today, having been replaced by twin-carbon-arc welding and other variations.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 metals. 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 extreme 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 arcElectric arc
An electric arc is an electrical breakdown of a gas which produces an ongoing plasma discharge, resulting from a current flowing through normally nonconductive media such as air. A synonym is arc discharge. An arc discharge is characterized by a lower voltage than a glow discharge, and relies on...
by Sir Humphry Davy in 1800, later repeated independently by a Russian physicist Vasily Vladimirovich Petrov
Vasily Vladimirovich Petrov
Vasily Vladimirovich Petrov was a Russian experimental physicist, self-taught electrical technician, academician of Russian Academy of Sciences ....
in 1802. Petrov studied electric arc and proposed its possible ways of usage, including for welding
Welding
Welding is a fabrication or sculptural process that joins materials, usually metals or thermoplastics, by causing coalescence. This is often done by melting the workpieces and adding a filler material to form a pool of molten material that cools to become a strong joint, with pressure sometimes...
.
The inventor of carbon-arc welding was another Russian, Nikolay Benardos
Nikolay Benardos
Nikolay Nikolayevich Benardos was a Ukrainian inventor who in 1881 introduced carbon arc welding, which was the first practical arc welding method.- References :* * at weldworld.ru...
, who developed this method in 1881 and patented it later under the name Elektrogefest ("Electric Hephaestus
Hephaestus
Hephaestus was a Greek god whose Roman equivalent was Vulcan. He is the son of Zeus and Hera, the King and Queen of the Gods - or else, according to some accounts, of Hera alone. He was the god of technology, blacksmiths, craftsmen, artisans, sculptors, metals, metallurgy, fire and volcanoes...
").
Variations
- Twin carbon arc weldingTwin carbon arc weldingUnlike single carbon arc welding, in twin carbon arc welding the arc is maintained between two carbon electrodes held in a special holder. Current is switched on and by operating the mechanism of arc length adjustment the two electrodes are brought closer...
(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.
(Picture provided by Answers.com, http://www.answers.com/topic/carbon-arc-welding?cat=technology)
External links
- The American Welding Society
- Commonly Used Welding Processes and their Abbreviation – Welding Inspection Services website
- Canadian Welding Association
- The Welding Institute
- Welding Process – Key to Steel (Online steel properties database)